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  • 1990-1994  (4,242)
  • 1920-1924  (3,032)
  • Inorganic Chemistry  (6,645)
  • Industrial Chemistry and Chemical Engineering  (629)
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  • 1
    Electronic Resource
    Electronic Resource
    New concepts for the design of mass polymerization reactors (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 127-130 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel reactor arrangement for the anionic polymerization of styrene described in this paper comprises alternating adiabatically operated plug-flow reactors and heat exchangers. A novel tube-bundle recycle reactor is presented for the bulk polymerization of styrene and acrylonitrile.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170210
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetics and mechanisms of reaction between carbon disulphide and morpholine in aqueous solutions (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 138-140 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The reaction in aqueous solutions between carbon disulphide and morpholine has been studied experimentally at 303 K using a conductimetric stopped-flow technique. The observed pseudo-first order rate constant does not vary linearly with amine concentration but follows the equation: \documentclass{article}\pagestyle{empty}\begin{document}$$ k_{obs} = k_{Am} [R_2 NH]^2 + k_w [R_2 NH][H_2 O] $$\end{document} .This equation is compatible both with (i) zwitterion intermediate and (ii) single-step termolecular reaction mechanisms which were previously proposed for the corresponding reactions of CO2 and COS. Values of rate constants kAm and kw at 303 K are also reported.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170212
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  • 3
    Electronic Resource
    Electronic Resource
    Continuous fermentation with product recovery by in-situ extraction (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 365-373 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The productivity of fermentations is often limited by end product inhibition. This can be avoided by continuous removal of the inhibiting product from the broth. Such in-situ separation can be conveniently accomplished by liquid-liquid extraction. As an example, the continuous fermentation of ethanol by the thermophilic, anaerobic bacterium Clostridium thermohydrosulfuricum is investigated in a 20-1 fermenter with simultaneous in-situ extraction by oleyl alcohol as organic solvent. Continuous fermentations with and without in-situextraction were carried out with systematic variation of the independent operating conditions, viz. feed glucose concentration, broth flow rate and solvent flow rate. The experimental results of 18 steady states are reported. They show that in-situ extractions doubles the yield, selectivity and space-time yield of ethanol in comparison to fermentations without in-situ extraction. A biomodel elucidates the influence of feed glucose concentration, broth flow rate and solvent flow rate on the productivity of the fermentation process. Finally, a cost model was developed for the investigated fermentation which allows economic evaluation of the results of experiments and simulation. A sensitivity study elucidates the economic limits and advantages of fermentation with in-situ extraction compared to a common fermentation without product separation.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170602
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  • 4
    Electronic Resource
    Electronic Resource
    Hydrogen consuming anodes for energy saving in sodium sulphate electrolysisDedicated to Professor Dr. Hartmut Wendt on the occassion of his 60th birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 382-389 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Gas diffusion electrodes, made of PTFE-bonded carbon with precious metal catalysts, were investigated as hydrogen consuming anodes in sodium sulphate electrolysis. The catalysts used were platinum and palladium and mixtures of both metals, prepared by two different methods. Various metal meshes were used as current collector. The electrodes performed well in pure sulphuric acid (5-15 wt-%) and in mixtures with sodium sulphate (10 wt-%) at temperatures of 30 to 70°C and current densities up to 5 kA/m2. In long-term experiments, at a current density of 2.6 kA/m2, the electrodes were stable over three months. The electrodes were characterised by stationary current density/potential curves and by galvanostatic current interruption measurements.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170604
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  • 5
    Electronic Resource
    Electronic Resource
    Swelling phenomena of emulsion liquid membranes with dithio-DEHPA as carrier (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 242-248 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The purpose of this paper is to investigate the swelling of emulsion liquid membranes using dithio-DEHPA as carrier. The application of interest was the removal of zinc from a synthetic aqueous solution which simulates a zinc plant effluent. The effect of several variables such as the concentration of carrier in the membrane, stirring speed and permeation time on the swelling of the emulsion is reported. Experimental results show that occlusion depends mainly on the amount of carrier in the membrane and can be significant when the concentration of carrier is lower than 6.0%. The interfacial tension analysis confirms that the size of globules is influenced by the concentration of carrier in the membrane. Stirring speed and permeation time are related to the water transport and must be kept at low values.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170405
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  • 6
    Electronic Resource
    Electronic Resource
    Hybrid modelling of yeast production processes - combination of a priori knowledge on different levels of sophisticationDedicated to Professor Dr. Dr. h. c. Hanns Hofmann on the Occasion of his 70th Birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 10-20 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Process models are used to formulate knowledge about process behaviour. They are applied, e.g., to predict the process' future behaviour and for state estimation when reliable on-line measuring techniques to monitor the key variables of the process are not available. There are different sources of information available for modelling, which provide process knowledge in different representations. Some elements or aspects may be described by physically based mathematical models and others by heuristically obtained rules of thumb, while some information may still be hidden in the process data recorded during previous runs of the process. Heuristic rules are conveniently processed with fuzzy expert systems, while artificial neural networks present themselves as a powerful tool for uncovering the information within the process data without the need to transform the information into one of the other representations. Artificial neural networks and fuzzy technology are increasingly being employed for modelling biotechnological processes, thus extending the traditional way of process modelling by mathematical equations. However, a sufficiently comprehensive combination of all these techniques has not yet been put forward. Here, we present a simple way of combining all the available knowledge relating to a given process. In a case study, we demonstrate the development of a hybrid model for state estimation and prediction on the example of a yeast production process. The model was validated during a cultivation performed in a standard pilot-scale fermenter.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170103
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  • 7
    Electronic Resource
    Electronic Resource
    HCl formation via pyrolytic degradation of polyvinyl chloride (PVC): An empirical approach to kinetic modelling (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 67-72 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The pyrolysis of polyvinyl chloride (PVC) has been described in terms of a relatively simple kinetic model, based on a large number of laboratory tests. The model predictions are in a good agreement with experimental data, regarding hydrochloric acid and non-condensable combustible gases. Therefore, the proposed model can be used to predict with good approximation the distributions of the above classes of compounds, in the whole range of applied experimental conditions.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170111
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  • 8
    Electronic Resource
    Electronic Resource
    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994) 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170101
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  • 9
    Electronic Resource
    Electronic Resource
    Design of a packed column for ethanol extraction. Equilibrium and kinetics studies (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 414-421 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Computer-aided design of a packed column to remove ethanol from aqueous solution with dibutyl butylphosphonate (DBBP) was accomplished with a programme based on the Pratt method and on the slip velocity equation. Reliable data for successful computation were obtained from literature correlations (drop size, hold-up and axial mixing coefficients for different types of packing) and from experimental work (equilibria and kinetics). Equilibrium studies on the H2O-ethanol-dibutyl butylphosphonate system were performed at different temperatures. A decrease in temperature increased the selectivity of the extractant while the distribution coefficient of ethanol, KD ≈ 1.0, remained constant. The behaviour of the system kinetics towards temperature is assessed in order to determine the initial mass transfer flux (892 × 10-3 kg m-2s-1, 30°C) and the activation energy, 22.9 kJ/kmol. The process is governed by the diffusion of the species involved. The influence of the type of packing of the column on its design is analyzed from the inventory volume of the solvent, the total volume of the column and the axial dispersion coefficients under normalised inlet and outlet conditions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170609
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  • 10
    Electronic Resource
    Electronic Resource
    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994) 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170501
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  • 11
    Electronic Resource
    Electronic Resource
    Determination of overall mass transfer coefficients in fixed bed sorption columns (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 285-289 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this study, a simple and effective technique for determining overall mass transfer coefficients in fixed bed sorption columns with recycle is presented. This new technique is free of the assumption of negligible time rate of solute concentration change in the fluid, i.e. (∂c/∂t) = 0, which has been widely used in former fixed bed sorption column analyses.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170411
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  • 12
    Electronic Resource
    Electronic Resource
    Comparison of the dynamic behaviour of packed and plate distillation columnsExpanded version of a paper presented by G. Fieg at the “Jahrestreffen der Verfahrensingenieure”, Nürnberg, September 29-October 1, 1993. (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 301-306 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The results of experimental investigations on distillation columns operating on a lab and on a production scale are presented and compared with the results obtained by simulation. There is good agreement between experiment and simulation. On the basis of these results a dynamic analysis was carried out. It compares the dynamic behaviour of packed and plate distillation columns of the same diameter and same number of theoretical plates. This reflects the influence of the different hold-ups of the two columns.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170503
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  • 13
    Electronic Resource
    Electronic Resource
    Modelling of coadsorption of different-sized molecules by using methods of statistical thermodynamicsDedicated to Professor Dr. Dr. h.c. Hanns Hofmann on the occasion of his 70th Birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 119-126 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Using methods of statistical thermodynamics, adsorption isotherms for the description of multicomponent chemisorption of different-sized molecular species are derived by assuming the adsorbing surface to be energetically homogeneous and by neglecting lateral interactions between the adsorbed particles. In the first part of this contribution, the adsorption equilibria for a mixture of different-sized chain molecules adsorbed on a lattice of coordination number z are discussed supposing each unit of a given chain to bind to one adsorption site only. In the second part, the coadsorption of molecular species consisting of a different number of segments on a continuous surface is treated. A comparison of the predicted to the measured isotherms for the coadsorption of two freon species on activated carbon shows that the proposed equations describe the results of the coadsorption measurements sufficiently well, provided the adsorption data for the pure components have been determined experimentally.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170209
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  • 14
    Electronic Resource
    Electronic Resource
    Single and multicomponent adsorption equilibria of carbon dioxide, nitrogen, carbon monoxide and methane in hydrogen purification processes (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 325-337 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Single, binary, ternary and quaternary adsorption equilibria of CO2, CO, CH4 and N2 on molecular sieve 5A and activated carbon were experimentally determined over a pressure range from 10-4 to 101 MPa, a temperature range from 303 to 363 K and at various compositions. The adsorption equilibria of steam reformer gases as needed for the hydrogen purification in pressure swing adsorption units were measured by using a circulating volumetric method. For the temperature-dependent correlation of pure gas isotherm fields the Toth equation, which is a favorable model for heterogeneous adsorbents, was extended by two parameters accounting for the temperature-dependencies of the saturation loading and the heterogeneity parameter. Multicomponent equilibria were successfully predicted from single component isotherms by the Ideal Adsorbed Solution Theory based on the accurate representation of the pure component data by this temperature dependent Toth equation. Other thermodynamic models like the HIAS, the MIAS, the SPD or the VS theory and the Statistical Thermodynamics Model were also applied to the prediction of the adsorption equilibrium and the temperature and pressure dependence of the selectivity, with comparable success, which is due to the quasi-ideal adsorption behavior even at a high pressure.
    Additional Material: 24 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170507
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  • 15
    Electronic Resource
    Electronic Resource
    Basic characteristics of spinel type manganese mixed oxide/titanium composite anodes for electroorganic redox catalysisDedicated to Professor Dr. Hartmut Wendt on the occasion of his 60th birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 338-347 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Manganese mixed oxide composite layers of about 1 μm thickness on titanium sheet as substrate were fabricated by firing of the corresponding nitrates at a typical temperature of 400°C in air. The activity of these anodes was evaluated by cyclic voltammetry (10 mV/s) and the stability was determined by chronopotentiometry (2.5 mA/cm2) in 1M H2SO4. The oxidation of 2-propanol was examined as a simple electroorganic model reaction. The quality of a first category of mixed oxides with general composition MnMe2O4 decresed in the order Me = Co, Ni, Fe. In a second group with the general formula MeMn2O4 a decrease in the order Me = Co, Cu, Fe, Ni, Ti, Zn, Cd, Ca, Mg, (Zn, Ge), Li was observed. The corresponding candidates of the second group were superior to those of the first. The anode service life τ of the optimum spinel anode CoMn2O4/Ti is dependent on the current density, according to jλ τ = const. (λ = 1.7). Thus high current densities are precluded. The mechanism has been discussed in terms of a heterogeneous redox catalysis: surface Mn(VII) states are formed in a slow electrochemical step. In a subsequent fast chemical oxidation of the organic molecule the original reduced state is regenerated. This also explains the comparatively good service life of these anodes.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170508
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  • 16
    Electronic Resource
    Electronic Resource
    Process for production of pure 4-methyl-1-pentene (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 354-357 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A process for the manufacture of pure 4-methyl-1-pentene by catalytic dimerization of propylene has been developed in three stages. The first stage involves preparation of a new process catalyst, which contains metallic sodium and potassium deposited on a Bulgarian natural zeolite, the support having been passivated previously by potassium carbonate. The experimental results demonstrate the advantages of the resulting catalyst over exisisting technology, namely 36% conversion and 92% selectivity relevant to liquid isomers. The second development stage concerns the technological regime of chemical reaction for production of 4-methyl-1-pentene. In the third stage, the regime conditions and equipment ensuring desired quality of the product and utilization of the unreacted propylene returned to the reactor are determined. Based on the studies of all stages, a flowsheet is proposed for synthesis and separation of the reaction mixture of isomeric hexenes to give pure 4-methyl-1-pentene.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170510
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  • 17
    Electronic Resource
    Electronic Resource
    On the para/ortho product ratio of phenol and anisole hydroxylation over titanium silicalite-1Dedicated to Professor Dr. Manfred Baerns on occasion of his 60th birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 348-353 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Titanium silicalite-1 samples of different particle size are synthesised and characterised by X-ray diffraction (XRD), photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), Raman and infrared spectroscopy. Size histograms are taken from transmission electron micrographs. Temporal changes of activity and selectivity for the hydroxylation of phenol and anisole are monitored. It is postulated that the p/o product ratios are due to the greater chemisorption of the ortho molecule.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170509
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  • 18
    Electronic Resource
    Electronic Resource
    Reduction of diesel particulate emissions by catalytic filtrationDedicated to Professor Dr. Dr. h. c. Hanns Hofmann on the occasion of his 70th birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 149-160 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Several kinds of diesel soot filters and filter materials of high melting points with eleven different catalytic coatings were prepared. They were calcined at a maximum temperature of 1000°C. The reaction rate and the kinetic parameters of the combustion of diesel soot were determined in a closed loop laboratory reactor. A packed bed of alumina particulates was the most active filter in soot combustion. Catalytic coatings with oxides of vanadium, copper or cerium accelerated the reaction. In each case the effect of the coating was dependent on specific interactions between the catalyst and the filter material. The manner of filtration and the nature of the soot filter are found to be more important for the overall result than the nature of the catalytic coating.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170303
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  • 19
    Electronic Resource
    Electronic Resource
    Investigations on precious metal/alumina interactions on three-way automotive emission control catalysts, BMA catalysts and model samplesDedicated to Professor Dr. Dr. h. c. Hanns Hofmann on the occasion of his 70th Birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 161-168 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Combined XPS and SIMS measurements, partly supplemented by XRD investigations, were utilized to detect precious metal/support interactions on catalysts containing various precious metals. The Klemm-Bronger reaction between Pt and α-Al2O3 on methane/ammonia catalysts was used as a standard reference. Evidence was found for different stages of Pt/Al interactions and changing electronic properties of Pt on the surfaces of these Pt/α-Al2O3 catalysts by means of XPS and SIMS, and in the bulk material by XRD. The SIMS investigations on Pt and Rh on γ-Al2O3 showed that, even at temperatures around 500 °C, Rh/Al interactions can appear to a small extent in the topmost atomic layers, whereas the Pt/γ-Al2O3 specimens did not show any measurable effects. After on-road operation, enhanced SIMS cluster-ion signals as well as anomalous XPS signal contributions were measured on the surfaces of used three-way automotive emission control catalysts. These signals did not appear for the fresh catalysts. By analogy with the related results reported on the methane/ammonia catalysts, the ion signals were used as qualitative surface probes indicating the presence of precious metal/support interactions, especially between Rh and Al.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170304
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  • 20
    Electronic Resource
    Electronic Resource
    Reaction engineering simulations of a fluidized-bed reactor for selective oxidation of fluorene to 9-fluorenonePaper presented at the DECHEMA Annual Meeting, May 26-28, 1993 in Nürnberg.Dedicated to Professor Dr. Dr. h. c. Hanns Hofmann on the occasion of his 70th birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 169-178 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The catalytic oxidation of fluorene to 9-fluorenone in a fluidized-bed reactor was investigated by modeling of the reactor and simulation of its performance. The “Bubble Assemblage Model” of Kato and Wen, the “Bubbling Bed Model” of Kunii and Levenspiel and the “Countercurrent Backmixing Model” of Potter were applied. From a comparison of simulation results obtained by the various fluidized-bed models and a fixed-bed model conclusions were drawn about the influence of interphase mass transfer and gas backmixing on the conversion of fluorene and slectivity of 9-fluorenone formation. Furthermore, the dependence of conversion and selectivity on temperature and hydrodynamic conditions was investigated. In particular, the implications of a change of hydrodynamic conditions for scale-up were analysed. The highest yield of 9-fluorenone predicted for a bench-scale fluidized bed amounted to 88% (XF = 97%, SNON = 91%). This yield was lower than in a fixed-bed reactor (YNON = 92%, XF = 99%, SNON = 93%). A further drop of the yield was predicted when scaling-up from a bench-scale reactor to a commercial size unit (YNON = 54%, XF = 86%, SNON = 63%).
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170305
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  • 21
    Electronic Resource
    Electronic Resource
    Conversion of ethanol over zeolite H-ZSM-5 (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 179-186 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The conversion of ethanol over H-ZSM-5 was studied as a function of ethanol partial pressure, reaction temperature, weight hourly space velocity and Si/Al ratio. The results obtained were in qualitative agreement with most of those in the literature. Combination with all published results to give a significant regression model was not possible due to the large scatter of the data from various scientific groups. In mechanistic investigations, temperature programmed reaction measurements of ethanol, diethyl ether and ethene were performed. The formation of ethene from ethanol via direct elimination or from diethyl ether as intermediate could be confirmed. In the conversion of ethanol/water mixtures, the product distribution did not change significantly up to a water content of 60 wt%. Then, a pronounced increase of ethene formation and a considerable decrease of the yields of aromatics was observed. When several reaction mixtures from syngas conversion to ethanol were converted over H-ZSM-5, the coking rate depended on the product distribution in the feed. Product mixtures from processes with higher amounts of compounds having an unfavourable C/H ratio led to rapid deactivation of the zeolite.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170306
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  • 22
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    Liquid phase oxidation of α-pinene initiated by ozone. 2: Formation of verbenol, verbenone and acid products (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 187-194 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The formation of verbenol, verbenone and acids during liquid phase ozone-initiated oxidation of α-pinene has been investigated; temperature, ozone partial pressure and ozone initiation time were the variables studied. While increasing temperature promotes the formation of secondary products, the other two variables affect mainly the selectivity. Thus, an ozone partial pressure and ozone initiation time of 1014 Pa and 10 min, respectively, lead to the highest selectivities. Kinetic expressions for the formation of verbenol and verbenone, which are consistent with experimental data, have also been developed from a free radical mechanism.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170307
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  • 23
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    Controlled precipitationPaper presented by A. Mersmann at the Meeting of German Chemical Engineers, Vienna, 30. Sept.-2. Oct. 1992. (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 1-9 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In a process of precipitation, two or more reactants form a product. In many cases, the solubility of this product is very low and high supersaturation is generated which leads to nucleation and crystal growth. The number of the formed nuclei and their growth govern the particle size distribution of the precipitate. As a rule, the precipitate is separated from the mother liquor in a centrifuge or on a filter. This separation and the subsequent drying process of very fine particles can be very expensive with respect to investment and energy costs. Therefore, it is desirable to produce as coarse a precipitate as possible with a narrow crystal size distribution.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170102
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  • 24
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    Electronic Resource
    Kinetic studies on high temperature desulphurization of synthesis gas with zinc ferrite (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 21-29 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The desulphurization of synthesis gas with zinc ferrite was studied in a laboratory-scale fixed-bed reactor. Desulphurization efficiency of 97-99% was obtained. The inlet hydrogen sulphide concentration was about 2600 ppm. A flat breakthrough curve showed that diffusion through the sulphide layer controlled the rate of sulphidization. The degrees of utilization varied between 5 and 11%. Experimental data formed the basis of a kinetic evaluation with the fixed bed model and the unreacted core model. Rate constants, reaction orders, and effective diffusion constants were calculated. When chemical reaction controlled the rate, the order of reaction was between zero and unity. The rate of reaction increased with temperature. Effective diffusivities were of the order of 10-5 m2 s-1, increasing slightly in the temperature range between 500 and 600°C. The activation energy was determined as 54 kJ mol-1, which corresponds to an unexpectedly strong temperature dependence of the diffusion-controlled reaction. The low degrees of utilization, and also the strong temperature dependence, are explained by sintering of the sulphidized zinc ferrite.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170104
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  • 25
    Electronic Resource
    Electronic Resource
    Supported nickel catalyst from hydroxycarbonate of nickel and aluminium (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 41-46 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The hydroxycarbonate of nickel and aluminium (Ni/ Al = 3) with a hydrotalcite-like structure is an outstanding precursor of the active component of supported nickel catalysts. Good mechanical strength and suitable nickel content of these catalysts, which are necessary for practical applications, can be achieved by mechanical mixing of this compound with an additional support. The catalyst prepared from a mixture of 56.5 wt-% of nickel-aluminium hydroxycarbonate and 43.5 wt-% of γ-alumina was proven to have a stable catalytic activity in the methanation reaction at 2 MPa and 800 K.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170107
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  • 26
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    Catalytic dehydrogenation of methanol to water-free formaldehydeDedicated to Professor Horst Langemann on the Occasion of his 65th Birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 34-40 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Catalytic dehydrogenation of methanol is a promising process of producing water-free formaldehyde. The present paper reviews research in this field. As effective catalysts mainly transition metal compounds as well as oxides and salts containing sodium have been reported. Several catalysts exhibit high activity and high selectivity, for formaldehyde at low conversions while further efforts have to be made to improve catalyst stability and selectivity at high conversions. Catalytic dehydrogenation of methanol to formaldehyde is compared with methanol oxidation.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170106
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  • 27
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    Removal of ethoxylated aliphatic amines from zinc containing effluents by adsorption on macroporous resinspaper presented at the sci conference iex '92 - ion exchange advances, cambridge, uk, 12-17 july, 1992. (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 30-33 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The separation of ethoxylated aliphatic amines from zinc containing effluents with macroporous polymeric adsorbents Wofatit EP 61, EP 62, Y 59, Y 77 and active carbons has been examined. The adsorption behaviour has been investigated as a function of temperature, time and concentration of Na2SO4, ZnSO4 and H2SO4. The macroporous polymers EP 61, Y 77 and Y 59 are capable of separating ethoxylated aliphatic amines from effluents of viscose fibre industry at higher temperatures and under weakly acidic conditions. In contrast to active carbon, inorganic components are not adsorbed on the investigated macroporous resins. Data obtained in a concentration range of 0 to 10 g of adsorbate per litre produced a Langmuir profile for adsorption of ethoxylated aliphatic amines by polymeric adsorbents.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170105
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  • 28
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    Non-Darcian non-isothermal compressible flow and heat transfer in cylindrical packed beds (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 50-60 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Knowledge of transport processes is of considerable practical importance in the design and performance evaluation of packed bed reactor systems. Acquisition of the required information necessitates a realistic mathematical description of the system. In this study, numerical analysis is performed for forced convective non-Darcian, non-isothermal compressible flow and heat transfer in cylindrical packed beds. Local structural and transport properties are considered. The influence of compressional work as well as viscous dissipation on the thermal field is evaluated and a general criterion provided for assessing the effect of expansion.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170109
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  • 29
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    Further remarks on the linear relationship between stoichiometry and dimensional analysisDedicated to Professor Dr. Horst Langemann on the Occasion of his 65th Birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 47-49 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The phrase “further remarks” in the title of this short paper is meant to imply that reactions and dimensionless groups are not only purely algebraic concepts, but definite numerical values can also be associated with them; in stoichiometry this evaluation may relate, for example, to the heat of reaction and, in dimensional analysis, to what is called a dimensionless number. On the basis of the evaluation concept, it will be shown that a counterpart of Hess' law in thermochemistry is valid in dimensional analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170108
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  • 30
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    Inertial impaction of aerosol particles on single and multiple spherical targets (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 88-94 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Inertial deposition of aerosol droplets (diameter: 1-14 μm) on steel spheres (diameter: 3-9 mm) was investigated. Air velocity was varied between 7 and 28 m/s (corresponding sphere Reynolds numbers: 1400-17000). The impaction on single spheres as well as that on linear arrays of eight spheres was measured. Theoretical results, based on potential flow investigations were verified by single sphere experiments. Of special interest was the range of lower Stokes numbers, where the theoretically predicted limit of deposition cannot be verified. The experiments on sphere arrays were for the first time performed in the low Stokes number range. Deposition on the leading sphere, relative to that on the shielded spheres, exhibits a maximum in the high Stokes number range, but this changes drastically in the low Stokes number range. Here, maximum deposition can be found on the shielded spheres while the leading sphere shows a markedly lower deposition.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170204
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  • 31
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    The cyclone scrubber - a high efficiency wet separator (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 73-80 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Due to induced turbulent interactions between particles to be separated and the scrubbing liquid present as droplets, very good collection efficiency down to submicron particle size can be achieved as shown by detailed studies [1]. Assumed are suitable flow conditions, a long residence time and a certain droplet size distribution or a special liquid dispersion system. As the name implies, the cyclone scrubber basically consists of a cyclone. This cyclone serves as a contact space in which the interaction between dust particles and scrubbing liquid droplets takes place, and as a droplet separator. Thus, under normal conditions, a water saturated but dust- and droplet-free gas stream leaves the cyclone. The droplets are generated by a pneumatic atomization nozzle, arranged at the cyclone inlet in the direction of flow. A complete theoretical description of the three-dimensional, three-phase, non-steady turbulent flow in the cyclone scrubber has not been possible up to now. The detailed experimental investigations presented in this work, and covering multiple parameters, led to physically based conclusions about the dominant interactions and separation mechanisms involved. Grade efficiencies which did not fall below 0.75, down to a particle size of 0.5 μm, could be measured by an optical particle counter. Collection efficiency of 99.2% was determined by gravimetric analysis of the dust load, according to VDI-guideline 2066, in the raw and clean gas sections of the dust load, according to VDI-guideline 2066, in the raw and clean gas sections of the cyclone scrubber.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170202
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  • 32
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    A rotating two-phase gas/liquid flow regime for pressure reduction in underwater plasma arc welding (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 81-87 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Plasma arc welding processes are used in the off-shore industry for construction and maintenance of underwater structures and pipelines in a wet environment. At greater water depths the density of the plasma gas increases because of the greater hydrostatic pressure. This causes conductive heat losses to the wet environment to increase. To maintain the energy flux to the workpiece to be welded, the plasma arc has to burn in a local dry area with an inside pressure of 1 bar. This requirement can be fulfilled by a rotating cylinder with a liquid film flowing down the inner wall. The flow around the rotating cylinder is experimentally investigated. The rotating cylinder is placed above the work surface which is simulated by a flat plate. Because of the centrifugal forces of the rotating flow inside the gap between the lower end of the cylinder and the flat plate the water is forced out of the cylinder. The velocity distribution in the flow is measured by laser Doppler anemometry. The phase distribution in the two-phase flow in the gap is measured by local electrical probes. The static pressure inside the gaseous atmosphere is reduced in comparison to the hydrostatic pressure of the surrounding water. The pressure reduction is given by the void fraction, the phase distribution and the volume flow rates of both phases in the gap as well as by the speed of revolution and the design of the cylinder and the work surface. The influence of these parameters on heat transfer from the workpiece to the two-phase flow regime is also investigated.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170203
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  • 33
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    Homogenization of liquids in tanks stirred by multiple impellers (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 95-101 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The process of homogenization of liquids in a tall vessel equipped with a multiple impeller was studied. Up to four standard Rushton turbines and/or six pitched-blade turbines were used. The mixing time in the system was measured by the conductivity method. A continuous time history of the tracer concentration at several points in the system was recorded. The data were interpreted by means of an adapted cell model of the flow within the stirred vessel with several impellers based on the assumption of well mixed cells and intercellular flow of liquid. The liquid transfer flow rate between the cells, as a parameter of the model, was calculated from experimental data. A good agreement between the time dependence of concentration obtained experimentally and that calculated from theory was obtained. A direct relationship between the flow numbers between cells and those of impellers was established.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170205
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  • 34
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    Heterogeneous catalytic methylation of catecholDedicated to Professor Dr. Dr. h. c. Hanns Hofmann on the occasion of his 70th Birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 108-111 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It has been shown that, after a partial deactivation, γ-alumina (γ-Al2O3) is a good catalyst for selective methylation of 1,2-benzenediol in the temperature range of 260-310°C. The main products are the desired 3-methyl-1,2-benzenediol and 2-methoxyphenol, which may be converted in another step into 3-methyl-1,2-benzenediol, giving an overall selectivity for the desired products of 80 to 90%. The catechol forms a strongly chemisorbed surface species on γ-alumina and its steric adsorption model correlates with the kinetic data.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170207
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  • 35
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    Deactivation of a vinyl acetate catalystDedicated to Professor Dr. Dr. h. c. Hanns Hofmann on the occasion of his 70th Birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 112-118 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Kinetic studies as well as morphological and physico-chemical surface studies have been carried out on the deactivation of a palladium carrier catalyst for vinyl acetate synthesis in the ethylene gas phase process. The experiments cover concentration and temperature ranges of technical interest at a total pressure of 900 kPa. The deactivation rate depends on the temperature and the oxygen and acetic acid concentrations. The decline in activity is best described by a rate law of second order relative to the activity number. This behaviour is attributed to the observed aggregation of finely dispersed palladium. It can be concluded that palladium(II) acetate acts as a transport species in a chemically assisted sintering mechanism. At temperatures T ≤ 438 K the more advantageous final texture of the catalyst will only be formed on reaction.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170208
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  • 36
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    Continuous computer controlled production of formate dehydrogenase (FDH) and isolation on a pilot scaleDedicated to Professor Dr. Dr. h.c. Hanns Hofmann on the occasion of his 70th Birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 131-137 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A continuous production process has been developed up to pilot scale (300 l) for FDH production with the methylotrophic yeast Candida boidinii. A high cell mass specific FDH activity (50 U/g) is achieved by process computer controlled supply of pure methanol to operate the reactor at an optimum methanol concentration of 10 g/l. The maximum FDH spacetime yield achievable with this process control involves a residence time of 7 h. The FDH space-time yield (STY) and FDH concentration are a function of the oxygen transfer rate (OTR) of the fermenter (maximum STY = 255 U/(l h) at kLa = 870 l/h). For a reasonable compromise between high FDH space-time yield and high FDH concentration, an optimum residence time is adjustable by regulating the supply of nutrient salt solution in relation to the OTR of the fermenter. On a pilot scale (200 l continuously stirred tank reactor) roughly 4 million U of FDH were produced within 10 days at a residence time of 14.3 h. Isolation of intracellular FDH enzyme was performed using extraction with an aqueous two-phase system (PEG/K2HPO4). A technical product quality of 1.2 U/mg FDH was achieved without any chromatographic purification step.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170211
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  • 37
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    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994) 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170301
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  • 38
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    A mathematical model describing the ARI “autocirculation reactor” for low temperature conversion of H2S into sulphur (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 141-143 
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    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A prototype “autocirculation”-type reactor has been designed and constructed at the N.I.O.C. Research Institute, Tehran and a mathematical model describing the concentration versus time profile subsequently developed. The model encompasses mass transfer considerations and kinetic studies of the regeneration reaction. For this purpose, the rate equation for iron complex oxidation, proposed by Japanese researchers, was modified and a new rate equation presented. This rate equation has been widely used in the above mentioned mathematical model. With this model, the vessel volume for a time-dependent H2S feed has been calculated for a “ZDDP” production unit.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170213
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  • 39
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    Applications of computational fluid dynamics in the chemical industryDedicated to Professor Dr. Dr. h. c. Hanns Hofmann on the occasion of his 70th Birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 145-148 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In order to illustrate the use of CFD in providing an understanding of mixing processes, three examples, mixing in a pipe, homogenization with a static mixer and flow in a mixing vessel with a Rushton turbine, are discussed and compared with experimental results. Special attention is focussed on the resultant concentration distribution, which is closely linked to turbulent properties. A semi-empirical model is presented for a quantitative prediction of the initial turbulent conditions. Using special numerical techniques a mixing vessel with wall-separated baffles, which represents a problem generally regarded as beyond the capabilities of numerical analysis, can be simulated.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170302
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  • 40
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    Dynamic response and safety assessment of a batch process on cooling breakdown (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 358-363 
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    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cooling breakdown in highly exothermic reaction processes may lead to runaway. The sensitivity and the safety assessment of a batch process on cooling breakdown are studied. The dependence of the minimum cooling time and the maximum allowable time of cooling breakdown for safe operation on the process parameters is investigated.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170511
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  • 41
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    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994) 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170601
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  • 42
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    Concept of a sterile concentration process for milk by multistage flash evaporationDedicated to Professor Dr. Dr. h. c. Hansjörg Sinn on occasion of his 65th birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 374-381 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the proposed combined sterilisation and concentration method, the original milk is first sterilised under conditions of continuous flow and after reaching the desired sterilisation temperature the product is concentrated by means of flash evaporation during subsequent cooling. Addition of stabilisers to maintain the thermal stability of the concentrate during sterilisation is not necessary in this process. The method presupposes that cooling with concentration is carried out under sterile conditions. This is technically quite feasible on use of multistage flash evaporation.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270170603
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  • 43
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    Pyrolysis of propane at reflected shock-wave temperatures from 1300 to 2700 K (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 195-200 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Shock tube pyrolysis of propane at temperatures between 1300 K and 2700 K at reflected shock pressures of 500 to 1500 kN/m2 has been investigated. The reaction is of 1st order with a rate constant K = 1.79 × 108 exp (-176.2 kJ/RT) s-1. The major reaction products were acetylene, ethylene and methane, while traces of propylene and ethane were only detected at temperatures below 1500 K. At higher temperatures, propane conversion to acetylene increased at the expense of the other products. Optimum conversions to ethylene and methane, in contrast to that to acetylene, were more sensitive to changes in temperature than to variations in reaction time. However, at reaction pressures above 550 kN/m2, extension of reaction time beyond 0.5 ms did not favour the formation of acetylene. A simple kinetic model which confirmed the experimental optimum product selectivity conditions is put forward.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270170308
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    Mass transfer and reaction behaviour of a circulating fluidized bed reactorPaper presented at the DECHEMA annual meeting, May 26-28, 1993, Nürnberg, GermanyDedicated to Prof. Dr. Dr. h. c. Hanns Hofmann on the occasion of his 70th birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 201-209 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This contribution presents a chemical reactor model of a circulating fluidized bed (CFB) which takes into account adsorption effects and provides a description of the vertical profiles of gas concentration in the riser. The oxidation of NO is used as an example of a heterogeneous catalytic reaction. Mass transfer between the gas phase and solid particles in the CFB was investigated at various temperatures and solids mass flow rates. The measurements show that the mass transfer coefficient decreases with increasing solids mass flux and that the CFB resembles a bubbling fluidized bed as regards gas-solid contacting.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170309
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  • 45
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    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994) 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170401
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  • 46
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    Kinetic study of the synthesis of n-octyl octanoate using cobalt chloride as catalyst (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 210-215 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of the pseudohomogeneous liquid phase synthesis of a high molecular weight ester in a stirred tank reactor using cobalt chloride as catalyst has been studied at various temperatures, catalyst concentrations, and acid/alcohol molar ratios. A kinetic model has been determined that predicts the experimental results quite well.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170310
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  • 47
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    A new design concept of structured packing column auxiliaries (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 61-66 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper discusses the criteria for obtaining an improved performance of structured packing columns in gas-liquid contacting, by improving the liquid and gas distributors. A new liquid distributor design, specific for structured packing columns is presented. Experimental measurements which quantify the improvements attained by the new distributor are also presented. Furthermore, gas flow distribution requirements for structured packing columns are discussed. Three “case studies” indicative of the implementation of the proposed distributor concept in industrial columns are included. Case (a) CO2/MEA removal column, case (b) ammonia splitter and case (c) acid gas neutralization column.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170110
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  • 48
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    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994) 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170201
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  • 49
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    Influence of viscosity on product distribution of fast competitive chemical reactions (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 102-107 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The objective of this study was to determine the influence of viscosity on micromixing in turbulent flow. It was first necessary to find a suitable viscosity-raising additive. HEC (hydroxyethyl cellulose) proved to be better than previously studied additives [sorbitol and carboxymethylcellulose (CMC)]. In concentrations up to 1 wt-%, HEC solutions are almost Newtonian with viscosities independent of pH over the range 2 to 10. HEC had no effect on the reaction rate constants and the spectrophotometric analysis of the fast, competing reactions used - the diazo coupling between 1-naphthol and diazotized sulphanilic acid. The viscosity can then be raised by around an order of magnitude by adding less than 1 wt-% HEC to this reaction system.Diazo couplings were conducted in a 20 1 semi-batch tank reactor stirred by a Rushton turbine at two viscosity levels (0.9 and 6.2 mPa s). Long feed times ensured that micromixing was controlling. More bisazo dye was formed in the more viscous solution, all other conditions being unchanged, indicating more intense segregation and slower micromixing.This was also shown by visualizing the extent of neutralisation zones, with more spreading and slower micromixing being observed in viscous solution. Higher turbine speeds reduced this spreading. One feed point near and one far from the turbine were employed: the strong inhomogeneity of the turbulence led to smaller amounts of bisazo dye when the feed was added to the turbine suction, irrespective of the viscosity. All results agreed with the trends predicted by the engulfment model of micromixing. Its simplest form assigns an average energy dissipation rate to the reaction zone: the values obtained are of similar magnitude to those measured by physical techniques and were related to the spreading of the reaction zone.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170206
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  • 50
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    Hydrogenation of carbon dioxide on cobalt catalysts - activation, deactivation, influence of carbon monoxideDedicated to Professor Dr. Manfred Baerns on occasion of his 60th birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 390-396 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A batch reactor directly combined with an ultrahigh vacuum apparatus, which is equipped with facilities for catalyst preparation and Auger electron spectroscopy, was used to answer some questions which had arisen in recent studies concerning carbon dioxide hydrogenation on pure metallic and supported Co catalysts. Both oxygen incorporated during oxidation/reduction cycles and carbon deposited when CO2 is hydrogenated penetrate deep into the bulk. This kind of carbon can easily be hydrogenated. CO strongly hinders the reduction of the oxidized Co surface in the H2/CO2 reaction mixture (4 : 1). CO hydrogenation is favoured over CO2 hydrogenation and leads to a higher percentage of C2 to C4 hydrocarbons as compared with CH4 formation.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170605
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  • 51
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    Liquid velocity and dispersion coefficient in an airlift reactor with inverse internal loopParts of this paper have been presented in a condensed version at CHISA '93, Praha, Czech Republic.Dedicated to Professor Dr. Manfred Baerns on the occasion of his 60th birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 401-405 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An airlift reactor with inverse internal loop (annulus sparged) is investigated with regard to liquid velocity and dispersion coefficient for the purpose of reactor design. To distinguish between the influence of the individual parts of the reactor (downcomer, riser, bottom) on the liquid velocity and mixing, several draft tubes with different geometries and draft tube bottom clearances are successively installed.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270170607
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  • 52
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    Recovery of zinc from pickling baths with amberlite LA-2. Influence of modifier on the extraction equilibrium (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 397-400 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The extraction of zinc chloride by Amberlite LA-2, a long chain secondary alkylamine, dissolved in Shellsol K, a naphthenic solvent, has been studied at room temperature. Isodecanol was used as modifier. The aqueous phases were chloride solutions of Zn(II) and Fe(II) in the concentration range commonly encountered in pickling baths, viz. about 1 and 1.5 mol/l, respectively. The ionic strength was kept constant at 4 mol/l in all experiments. Measurement of the distribution equilibrium of zinc chloride was carried out over wide concentration ranges of amine, zinc chloride, free chloride and isodecanol. It was assumed that the zinc chloride was extracted according to the following reaction \documentclass{article}\pagestyle{empty}\begin{document}$${\rm ZnCl}_{2,{\rm aq}} + 2{\rm AHCl}_{2,{\rm org}} \leftrightarrow ({\rm AH})_2 {\rm ZnCl}_{4,{\rm org}} $$\end{document}On the basis of this reaction, an easy to use model was developed to describe the extraction behaviour of Zn in typical pickling baths. Prediction and optimization of a solvent extraction plant performance under changing industrial feed conditions is then possible. This model takes account of the influence of isodecanol used as modifier.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170606
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  • 53
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    Applicability of explicit enhancement factors in the modelling of gas-liquid reactors (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 430-434 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170611
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  • 54
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    Temperature oscillation calorimetry in stirred tank reactors with variable heat transferDedicated to Professor Dr. rer. nat. Dr.-Ing. E. h. Hansjörg Sinn on the occasion of his 65th birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 406-413 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new method for applying reaction calorimetry to stirred tank reactors with variable heat transfer is presented. Sinusoidal temperature oscillations are induced by an electrical heater placed either in the reactor or in the jacket in order to decouple the chemical heat production from the variable heat transfer during reaction. Multiplication of the reactor heat balance by periodic functions and integration yields the overall heat transfer. Temperature oscillation calorimetry was successfully applied to the free radical polymerization of methyl methacrylate in ethyl acetate which shows a strong decrease in heat transfer.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170608
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  • 55
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    Mathematical simulation of bioseparation in an affinity packed column (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 422-429 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Affinity chromatography (biospecific adsorption) relies on specific interactions of biological molecules such as enzymes, antigens, antibodies, and proteins. The process consists of three steps: adsorption, washing, and elution. A mathematical model including convection, diffusion, and reversible reaction is formulated to analyse the breakthrough behaviour of the solute. A moving finite element orthogonal collocation method is applied with respect to the space variables of the governing partial differential equations of the model to evaluate the breakthrough of the solute. Danckwerts' boundary conditions are considered for the column. The validity of the numerical scheme is checked by comparison with an analytical solution for a simplified model. The results obtained from model simulation show that the breakthrough time of the solute is significantly influenced by the axial dispersion coefficient, solute concentration, ligand content, reaction kinetics, particle porosity, particle size, and flow rate. Solute recovery and bed utilisation efficiencies are evaluated for different values of the above parameters.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170610
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  • 56
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    Study of drop-interface coalescence: Drainage time measurement (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 249-254 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An automatic apparatus has been developed and set up for the study of drop-interface coalescence. Most other studies have concentrated on events when the drop arrives at the interface with its terminal velocity. In our case, the drop is maintained fixed at the tip of a needle, and the interface is moved towards the drop at a controlled speed. The coalescence times are measured by means of a vectorial video camera focused on the drop. Several times are measured by means of a vectorial video camera focused on the drop. Several parameters have been investigated, such as the drop diameter, the relative drop-interface velocity, the phase system, the presence and the direction of mass transfer.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170406
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  • 57
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    A general simulation model of batch chemical reactors for thermal control investigations (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 255-268 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper describes the development of a dynamic simulation model for stirred tank batch or semi-batch chemical reactors fitted with an alternative heating-cooling system. Heat and mass balances are established for the reactor and its jacket. Since the general purpose of our research is the thermal control of these reactors, special attention is devoted to the behaviour of the heating-cooling system. In this article, we are particularly concerned with an alternative system, i.e. different fluids at a constant temperature can be alternatively delivered to the jacket. The computer simulation programme is flexible, enabling simulation of a batch or semi-batch reaction vessel, ranging from a laboratory pilot plant to a full-scale production plant. A control algorithm is included which allows reactor operation with open or closed-loop temperature control. To demonstrate the good performance of the simulation model, experimental results are presented for both a pilot plant and an industrial reactor.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170407
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  • 58
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    Development of a mathematical model for a secondary reformerIICT Communication No. 3238. (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 273-279 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A rigorous one-dimensional heterogeneous model is developed for a secondary reformer in an ammonia plant with special emphasis on the catalyst particle models. These are based on the effective diffusivity model and the Stefan-Maxwell model in the catalyst pore and the film around the catalyst particle. The performance of these four models is evaluated for the data collected from a commercial reformer in the complete operating range and recommendations are made regarding the use of appropriate particle models. The models for the catalyst particle show considerable deviations at the particle level but the reformer simulations produce almost identical results at the global level for all the four particle models. The need for a rigorous treatment of interphase resistance to mass transfer has been clearly demonstrated by comparison of the present model with the model of Singh and Saraf.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170409
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  • 59
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    Crystallization process optimization using artificial neural networksPaper presented by A. Woinaroschy at the 11th Internationai Congress of Chemical Engineering “Chisa '93”, Praha, August 29-September 3, 1993. (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 269-272 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper presents a new procedure for optimization of continuous mixed suspensionmixed product removal (MSMPR) crystallizing systems. Owing to the difficulties of theoretical modelling, simulation of the MSMPR crystallization process is based on the use of artificial neural networks (ANN). The optimization criterion is a compound objective function corresponding to an intended mean crystal size dimension and a minimal dispersion. The presence of multiple local minima has called for investigation by several optimization techniques. Ultimately, Luus' and Jaakola's random adaptive method proved to be most effective. The results obtained lend support to the general procedure proposed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170408
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  • 60
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    Unsteady two-film model for mass transfer (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 280-284 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The classical two-film model for mass transfer between two fluid phases can only be used to describe the steady state mass transfer mechanism. Both the penetration and the film-penetration model are also valid solely when only one diffusion boundary layer exists at the interface between the phases. With a view to surmounting the limitations of the above models a new model has been developed for the mass transfer between two fluid phases with two diffusion boundary layers at the interface. The new model is based on the two-film concept and the Danckwerts distribution function, and is also able to simulate the unsteady state mass transfer mechanism between two fluid phases with two different boundary layers.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170410
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  • 61
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    Agriculture wastes. A source of bulk products?Dedicated to Professor Dr. Manfred Baerns on the occasion of his 60th birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 291-300 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biotechnological production processes for low-molecular bulk chemicals can only compete with their petrochemical counterparts on using inexpensive raw materials, e.g., agricultural by-products or wastes, otherwise requiring disposal. The upgrading of by-products/wastes of potato starch production and the use of potato protein liquor and potato pulp for the production of bulk chemicals were investigated. It transpired that the economy of these processes depends on the waste disposal costs of the upgrading processes. In addition, it is shown that specialty chemicals can be produced economically from wastes. However, since they are produced in a large quantities, the upgraded product cannot be put on the market without ruining existing prices.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170502
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  • 62
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    Distribution of energy dissipation rate in an agitated gas-liquid system (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 323-324 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170506
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  • 63
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    Comparison of the single-bubble-class and modified two-bubble-class models of bubble column reactors (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 313-322 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Gas phase conversions and product selectivities predicted by the single-bubble-class and modified two-bubble-class models of bubble column reactors are compared for a multistep gas-liquid reaction involving series/parallel steps. A situation is considered where the first reaction step is fast and occurs in the interfacial region while the other reaction steps are slow and occur only in the liquid bulk. Equivalent hydrodynamic and transport parameters provide a common basis for the comparison. The differences in the gas phase conversions predicted by these models are insignificant. However, the two models predict very different values of selectivities for the intermediate products. This analysis enables us to judge the range of applicability of the single-bubble-class model in design and scale-up of bubble column reactors.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170505
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  • 64
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    The cocurrent downflow contactor-a novel reactor for gas-liquid-solid catalysed reactions (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 307-312 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Cocurrent Downflow Contactor (CDC) has been developed as a mass transfer and reactor device, with and without addition of tangential (swirl) flow, giving gas hold-up (Eg) values of 0.5-0.75, interfacial areas in the range 1000-6000 m2m-3 liquid and kLa values in the range of 0.15-1.55 s-1 for absorption using the O2/H2O system. It has been studied as a catalytic slurry reactor for the hydrogenation of (i) itaconic acid and (ii) triglycerides catalysed by Pd and Ni catalysts. The reactions were observed to be largely surface-reaction rate controlled, due to the very efficient mass transfer (kLa up to 11.75 s-1 under reaction conditions) and application of swirl flow-enhanced reaction rates. The CDC has recently been found to be capable of operating as a fixed bed reactor, thus eliminating a downstream catalyst separation problem (therefore more cost effective), and is superior in its mass transfer characteristics to other known devices. Scale-up can be undertaken without loss of performance efficiency.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270170504
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    Air purification by catalytic oxidation in a reactor with periodic flow reversalDedicated to Professor Dr. Dr. h. c. Hanns Hofmann on the occasion of his 70th birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 217-226 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The behaviour of an adiabatic packed bed reactor with periodic flow reversal has been studied by means of model calculations. A heterogeneous model as well as a pseudo-homogeneous model have been developed. It is shown that a high degree of conversion can be obtained in an autothermal process even with very low adiabatic temperature rises of some 10 to 20 K. The reactor is insensitive to fluctuations in inlet concentrations and in through-put. Short-cut methods proposed in the literature for calculating the plateau temperature in the pseudo-steady state are studied. The so called countercurrent-flow reactor approach showed reasonable agreement with the plateau temperature obtained by dynamic calculations with the full reactor model.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270170402
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    Mixing of large volume gas flows in pipes and ducts. Visualization of concentration profiles (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 227-234 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Concentration profiles are measured during the mixing process of carbon dioxide and air, which were injected into the rectangular cross section of a duct. The volume flow rates of both components differ considerably. The non-stationary and three-dimensional concentration fields are measured by optical tomography using holographic interferometry as the measuring principle. Projection data from four different viewing angles are used for tomographic reconstruction by the ART method. Pressure losses due to mixing processes are also measured. Results are presented for different angles of injection and different ratios of momentum flow rate for single and multiple jets of carbon dioxide which were injected into the carrier gas stream of air.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270170403
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    Estimation of the drying rate and moisture profiles in an industrial spray dryer by means of experimental investigations and a simulation study (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 235-241 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A spray dryer simulation program is described. It is based on the known conservation laws and permits determination of temperature and moisture profiles and droplet trajectories inside spray dryers. An industrial spray dryer used in the manufacture of detergents serves as an example to demonstrate the applicability of the program; this approach required prior experimental determination of the flow field and an axial temperature profile. On the basis of a rough estimate of the drying rate in the spray dryer, good agreement was observed between experiment and simulation.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270170404
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  • 68
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    N(B(NMe2)2)(Si(NMe2)3)(Ti(NMe2)3), [N(Si(NMe2)3)(Ti(NMe2)2)]2 und N(SiMe3)(Si(NMe2)3)(Ti(NMe2)3)  -  Synthese und Charakterisierung neuer molekularer Einkomponentenvorläufer für nitridische und carbonitridische Keramiken (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 366-370 
    Details
    ISSN: 0044-2313
    Keywords: Bis(dimethylamino)boryl-tris(dimethylamino)silyl-tris(dimethylamino)titanylamin ; N,N′-Bis(tris(dimethylamino)-silyl)-1,1,3,3-tetrakis(dimethylamino)cyclobistitanazan, Trimethylsilyl-tris(dimethylamino)silyl-tris(dimethylamino)titanylamin ; Trimethylsilyl-tris(dimethylamino)-silylamin ; synthesis ; nmr spectra ; mass spectra ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N(B(NMe2)2)(Si(NMe2)3) (Ti(NMe2)3), [N(Si(NMe2)3)(Ti(NMe2)2)]2 und N(SiMe3)(Si(NMe2)3)(Ti(NMe2)3)  -  Synthesis and Characterization of New Molecular Single-source Precursors for Nitride and Carbonitride CeramicsSynthesis and spectroscopic data of the title compounds are reported. [N(Si(NMe2)3)(Ti(NMe2)2)]2 crystallizes in the space group P1, a = 8.406(7), b = 10.673(8), c = 10.872(6) Å, α = 68.45(4)°, β = 71.72(4)°, γ = 78.11(7)°, 2 877 diffractometer data (Fo ≥ 2σFo), R = 0.051. The compound is characterized by a planar four-membered Ti2N2-ring with exocyclic tris(dimethylamino)silyl substituents attached to the nitrogen atoms of the ring.
    Notes: Darstellung, kernresonanz- und massenspektroskopische Daten der Titelverbindungen werden mitgeteilt. [N(Si(NMe2)3)(Ti(NMe2)2)]2 kristallisiert in der Raumgruppe P1 mit den Gitterkonstanten a = 8,406(7), b = 10,673(8), c = 10,872(6) Å, α = 68,45(4)°, β = 71,72(4)°, γ = 78,11(7)°. 2 877 Diffraktometerdaten (Fo ≥ 2σFo), R = 0,051. Die Verbindung besitzt einen planaren Ti2N2-Vierring mit exocyclischen Tris(dimethylamino)silylsubstituenten an den Stickstoffatomen des Rings.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200228
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    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994) 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946200301
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  • 70
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    Darstellung und Strukturen einiger N-(Tri-t-butoxysilyl)anilin-Derivate (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 377-384 
    Details
    ISSN: 0044-2313
    Keywords: One-pot reactions of tri-t-butoxychlorosilane, K-t-butanolate and substituted anilines. Crystal structure analyses of N-(tri-t-butoxysilyl)-aniline, C18H33NO3Si ; N-(tri-t-butoxysilyl)-p-nitroaniline, C18H32N2O5Si ; N-Methyl-(N-tri-t-butoxysilyl)-p-nitroaniline C19H34N2O5Si ; N-(tri-t-butoxysilyl)-p-cyanoaniline, C19H32N2O3Si ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Formation and Structures of N-(tri-t-butoxysilyl)aniline CompoundsPara-substituted N-(tri-t-butoxysilyl)anilines (t-BuO)3SiNRC4H4X-p, R = H, CH3, with substituents of high electron affinity (X = CN, NO2) were prepared by a one-pot reaction of tri-t-butoxychlorsilane, potassium t-butanolate and substituted anilines. Corresponding compounds with substituents of low electron affinity (X = OMe, H) preferably were prepared by metalation of anilines with sodium amide. Four crystal structures were determined. N-(tri-t-butoxysilyl)-p-nitro-aniline, N-methyl-(N-tri-t-butoxysilyl)-p-nitroaniline and N-(tri-t-butoxysilyl)-p-cyanoaniline crystallize at 298 K monoclinically, N-(tri-t-butoxysilyl)aniline crystallizes orthorhombically.
    Notes: Derivate des para-substituierten N-(Tri-t-butoxysilyl)anilins (t-BuO)3SiNRC6H4X-p, R = H, CH3 mit Substituenten hoher Elektronenaffinität (X = CN, NO2) wurden nach einem neuen Eintopfverfahren aus Tri-t-butoxychlorsilan, Kalium-t-butanolat und dem entsprechend substituierten Anilin dargestellt. Für Substituenten niederer Elektronenaffinität (X = OMe, H) wird die Methode der Metallierung von Anilinen mit Natriumamid bevorzugt. Vier Kristallstrukturen wurden bestimmt. N-(Tri-t-butoxysilyl)-p-nitroanilin, N-Methyl-(N-tri-t-butoxysilyl)-p-nitroanilin und N-(Tri-t-butoxysilyl)-p-cyanoanilin kristallisieren bei 298 K monoklin, N-(Tri-t-butoxysilyl)anilin kristallisiert orthorhombisch.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200230
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    Densities of Melts of the System KF—K2MoO4—B2O3 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 385-388 
    Details
    ISSN: 0044-2313
    Keywords: Density of melts ; system potassium fluoride/potassium molybdate/boron oxide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dichte der Schmelzen des System KF/K2MoO4/B2O3Die Dichte der Schmelzen des Systems KF/K2MoO4/B2O3 wurden gemessen. Das Molvolumen des binären Systems KF/K2MoO4 weicht nur wenig vom idealen Verlauf ab, was die starke thermische Dissoziation des kongruent schmelzenden K3FMoO4 anzeigt. Im System KF/B2O3 führt die Bildung von KBF4 und K2B4O7 zur Volumenzunahme, wie auch im System K2MoO4/B2O3. In letzterem kann die Volumenzunahme durch die Bildung des Heteropolyanions [BMo6O24]9- beschrieben werden. Die deutliche Abweichung vom idealen Verhalten des Systems KF/K2MoO4/B2O3 weist auf eine ausgeprägte ternäre Wechselwirkung, wahrscheinlich auf die Substitution von Sauerstoff in der Koordinationssphäre des Heteropolyanions durch Fluor.
    Notes: The density of melts of the system KF—K2MoO4—B2O3 was measured. The molar volume in the binary system KF—K2MoO4 deviates only little from the ideal course, which indicates the extended thermal dissociation of the congruently melting additive compound K3FMoO4.In the KF—B2O3 binary system the formation of KBF4 and K2B4O7 leads to the volume expansion, like in the K2MoO4—B2O3 system, where the volume expansion may be described by the formation of the heteropolyanions [BMo6O24]9-. The significant deviation from the ideal behaviour in the ternary system KF—K2MoO4—B2O3 refers to the pronounced interaction, most probably due to the substitution of oxygen atoms in the coordination sphere of the heteropolyanion with the fluorine ones.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200231
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    Synthesis and Crystal Structure of Hg5Sb2I6 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 389-392 
    Details
    ISSN: 0044-2313
    Keywords: Mercury antinionide iodide, Hg5Sb2I6 ; Preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese und Kristallstruktur von Hg5Sb2I6Das Antimonid-Iodid von Quecksilber, Hg5Sb2I6, früher irrtümlich als Hg3Sb2I4 formuliert, wurde in Standardampullen synthetisiert. Einkristalle wurden mittels Transport über die Gasphase erhalten. Hg5Sb2I6: Raumgruppe Pc21n, Gitterparameter: a = 8,108(1), b = 10,702(1), c = 21,295(1) Å. Die Struktur (Einkristall) ist aus [HgSbI3]-Tetraedern und [HgSbI2]-Dreiecken aufgebaut. Alle Antimonatome sind paarweise zu Sb24--Hanteln verbunden. Die Struktur wird mit anderen Strukturen, die Sb24--Hanteln enthalten, verglichen.
    Notes: Mercury antimonide iodide, Hg5Sb2I6, previously and erroneously reported as Hg3Sb2I4 was synthesized using standard ampoule technique. A gas-phase transport reaction was applied for preparation of single crystals. Hg5Sb2I6 crystallizes in the space group Pc21n (No. 33) with unit cell dimensions: a = 8.108(1), b = 10.702(1), c = 21.295(1) Å. Crystal structure solved using single crystal X-ray data is built of [HgSbI3] tetrahedra and [HgSbI2] triangles. All antimony atoms are joined into Sb24- dumbbells. The structure is compared with ones containing similar Sb24- dumbbells.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200232
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    Alkylidinphosphane und -arsane. I [P ≡ C—S]-[Li(dme)3]+ - Synthese und StrukturProfessor Reinhard Schmutzler zum 60. Geburtstage gewidmet (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 405-417 
    Details
    ISSN: 0044-2313
    Keywords: Tris(1,2-dimethoxyethane-O,O′)lithium 2λ3-phosphaethynylsulfanide ; [P≡C—S]--anion ; [Li(dme)3]+-cation ; heteroatom-substituted λ3-phosphaalkynes ; nmr and ir data ; X-ray structure determination ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Alkylidynephosphanes and -arsanes. I [P ≡ C—S]-[Li(dme)3]+ - Synthesis and StructureO,O′-Diethyl thiocarbonate and bis(tetrahydrofuran)-lithium bis(trimethylsilyl)phosphanide dissolved in 1,2-dimethoxyethane, react below 0°C to give ethoxy trimethylsilane and tris(1,2-dimethoxyethane-O,O′)lithium 2λ3-phosphaethynylsulfanide - [P≡C—S]- [Li(dme)3]+ - (1a). Apart from bis(trimethylsilyl)sulfane or carbon oxide sulfide, dark red concentrated solutions of λ3-phosphaalkyne 1 are also obtained from reactions of carbon disulfide with bis(tetrahydrofuran)-lithium bis(trimethylsilyl)phosphanide or with the homologous lithoxy-methylidynephosphane (2) [1]. The ir spectrum shows two absorptions at 1762 and 747 cm-1 characteristic for the P≡C and C—S stretching vibrations. The nmr parameters {δ(31P) - 121.3; δ(13C) 190.8 ppm; 1JCP 18.2 Hz} resemble much more values of diorganylamino-2λ3-phosphaalkynes than those of bis(1,2-dimethoxyethane-O,O′)lithoxy-methylidyne-phosphane (2a). As found by an X-ray structure analysis (P21/c; a = 1192.6(16); b = 1239.1(19); c = 1414.8(26) pm; β = 105.91(13)° at -100 ± 3°C; Z = 4 formula units; wR = 0.064) of pale yellow crystals (mp. + 16°C) isolated from the reaction with O,O′-diethyl thiocarbonate, the solid is built up of separate [P≡C—S]- and [Li(dme)3]+ ions. Typical bond lengths and angles are: P≡C 155.5(11); C—S 162.0(11); Li—O 206.4(17) to 220.3(20) pm; P≡C—S 178.9(7)°.
    Notes: O,O′-Diethylthiocarbonat setzt sich mit Bis-(tetrahydrofuran)lithium-bis(trimethylsilyl)phosphanid in 1,2-Dimethoxyethan unterhalb 0°C zu Ethoxy-trimethylsilan und Tris(1,2-dimethoxyethan-O,O′)lithium-2λ3-phosphaethinylsulfanid - [P≡C—S]-[Li(dme)3]+ - (1a)1,2-Dimethoxyethan (dme); Tetrahydrofuran (thf); Bis(2-methoxyethyl)ether (diglyme). Den λ3-Phosphaalkinen P≡C—S—Li und P≡C—O—Li werden unabhängig vom Gehalt an koordinierendem Solvens und der Konstitution die Ziffern 1 und 2 zugeordnet; bei den röntgenstrukturanalytisch untersuchten Komplexen [P≡C—S]-[Li(dme)3]+ und P≡C—O—Li(dme)2 kommt das Suffix a hinzu. um. Das als dunkelrote, konzentrierte Lösung erhaltene λ3-Phosphaalkin 1 entsteht neben Bis(trimethylsilyl)sulfan bzw. Kohlenstoffoxidsulfid auch bei den Umsetzungen von Kohlenstoffdisulfid mit Bis(tetrahydrofuran)lithium-bis(trimethylsilyl)phosphanid oder dem homologen Lithoxy-methylidinphosphan P≡C—O—Li (2) [1]. Das IR-Spektrum weist die für eine P≡C- und C—S-Valenzschwingung charakteristischen Absorptionen bei 1762 und 747 cm-1 auf; die NMR-Parameter {δ(31P) - 121,3; δ(13C) 190,8 ppm; 1JCP 18,2 Hz} gleichen mehr den Werten der Diorganylamino-2λ3-phosphaalkine als des Bis(1,2-dimethoxyethan-O,O′)-lithoxy-methylidinphosphans (2a). Nach den Ergebnissen einer Röntgenstrukturanalyse (P21/c; a = 1192,6(16); b = 1239,1(19); c = 1414,8(26) pm; β = 105,91(13)° bei -100 ± 3°C; Z = 4 Formeleinheiten; wR = 0,064) an blaßgelben, aus einem Ansatz mit O,O′-Diethylthiocarbonat isolierten Kristallen (Schmp. + 16°C) liegen im Festkörper getrennte [P≡C—S]-- und [Li(dme)3]+-Ionen vor. Charakteristische Bindungslängen und -winkel sind: P≡C 155,5(11); C—S 162,0(11); Li—O 206,4(17) bis 220,3(20) pm; P≡C—S 178,9(7)°.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200303
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    Pr(CH3COO)3, ein wasserfreies Selten-Erd-Acetat mit Netzwerkstruktur (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 438-443 
    Details
    ISSN: 0044-2313
    Keywords: Praseodymium(III) Acetate ; Synthesis ; Crystal Structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pr(CH3COO)3, an Anhydrous Rare-Earth Acetate with a Network StructurePr(CH3COO)3 may be prepared by dehydration of Pr(CH3COO)3 · 1,5 H2O at 180°C as an amorphous green powder. Single crystals were grown from the powder by addition of (NH4)CH3COO as „mineralisator“ at 180°C in a sealed glass ampoule. The crystal structure (tetragonal, P421c (no. 114), Z = 24, a = 2106.5(3), c = 1323.6(1) pm, Vm = 147.39(3) cm3/mol, R = 0.055, Rw = 0.029) was determined from four-circle-diffractometer data. The Pr3+ ions occupy three crystallographically independent positions and are surrounded by 9 and 10 oxygen atoms, respectively. Acetate ions connect the cations to a complicated three-dimensional network.
    Notes: Pr(CH3COO)3 entsteht beim Entwässern von Pr(CH3COO)3 · 1,5 H2O bei 180°C als amorphes Pulver. Einkristalle konnten daraus mit Hilfe von (NH4)CH3COO als „Mineralisator“ ebenfalls bei 180°C in einer geschlossenen Glasampulle gezüchtet werden. Die Kristallstruktur (tetragonal, P421c (Nr. 114), Z = 24, a = 2106,5(3), c = 1323,6(1) pm, Vm = 147,39(3) cm3/mol, R = 0,055, Rw = 0,029) wurde anhand von Vierkreis-Diffraktometerdaten bestimmt. Pr3+-Ionen besetzen drei unterschiedliche kristallographische Positionen und sind von 9 bzw. 10 Sauerstoffatomen umgeben. Acetationen verbinden die Kationen auf unterschiedliche Weise zu einem komplizierten dreidimensionalen Netzwerk.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200306
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    Die Chloride Na3xM2-xCl6 (M = La—Sm) und NaM2Cl6 (M = Nd, Sm): Derivate des UCl3-Typs. Synthese, Kristallstruktur und Röntgenabsorptionsspektroskopie (XANES) (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 444-450 
    Details
    ISSN: 0044-2313
    Keywords: Chlorides ; lanthanides ; synthesis ; crystal structure ; X-ray absorption spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Chlorides Na3xM2-xCl6 (M = La—Sm) and NaM2Cl6 (M = Nd, Sm): Derivatives of the UCl3-Type of Structure. Synthesis, Crystal Structure and X-Ray Absorption Spectroscopy (XANES)Single crystals of the derivatives of the UCl3-type structure Na3xM2-xCl6 (M = La/x = 0.364(4); Ce/0.349(5); Pr/0.318(8); Nd/0.305(5); Sm/0.246(4)) and NaSm2Cl6 were grown by different methods generally under reducing conditions. They are addition [Na(Sm2)Cl6] and addition/substitution variants [Na2x(NaxM2-x)Cl6] of the UCl3 structure type [□(U2)Cl6]. X-Ray Absorption Spectroscopy (XANES) at the LIII edge characterizes NaSm2Cl6 and NaNd2Cl6 as mixed-valence compounds with valences of +2 and +3 in statistical distribution (approximately 1:1) for Sm and Nd, respectively.
    Notes: Einkristalle der Derivate des UCl3-Typs Na3xM2-xCl6 (M = La/x = 0,364(4); Ce/0,349(5); Pr/0,318(8); Nd/0,305(5); Sm/0,246(4)) sowie von NaSm2Cl6 wurden auf unterschiedlichen Wegen, im allgemeinen unter reduzierenden Bedingungen erhalten. Sie sind Additions- [Na(Sm2)Cl6] bzw. Additions- / Substitutionsvarianten [Na2x(NaxM2-x)Cl6] des UCl3-Strukturtyps [□(U2)Cl6]. Röntgenabsorptionsspektren (XANES) an der Lm-Kante charakterisieren NaSm2Cl6 und NaNd2Cl6 als gemischtvalente Verbindungen mit Valenzen von +2 und +3 in statistischer Verteilung (etwa 1:1) für Sm bzw. Nd.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200307
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    Synthesis, structures and luminescence of two new Europium(II) Silicate-Chlorides, Eu2SiO3Cl2 and Eu5SiO4Cl6 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 451-456 
    Details
    ISSN: 0044-2313
    Keywords: Silicates ; crystal structure ; europium ; luminescence ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese, Strukturen und Lumineszenz von zwei neuen Europium(II)-silicat-chloriden, Eu2SiO3Cl2 und Eu5SiO4Cl6Eu2SiO3Cl2 und Eu5SiO4Cl6 wurden durch Erhitzen von EuCl2 mit EuSiO3 bzw. Eu2SiO4 gewonnen, Sr2SiO3Cl2:Eu2+ aus einem Gemenge von SrCO3, Eu2O3, SrCl2 · 6H2O und SiO2 unter reduzierenden Bedingungen. Die Kristallstrukturen von Eu2SiO3Cl2 [a = 1118,7(5), c = 952,6(1) pm, tetragonal, I4/m, Z = 8, R = 3,3, Rw = 3,0%] und Eu5SiO4Cl6 [a = 900,4(1), b = 1401,7(2), c = 1112,3(2) pm, β = 103,51(1)°, monoklin, C2/c, Z = 4, R = 3,6, Rw = 2,6%] wurden aus Einkristall-Vierkreisdiffraktometer-Daten bestimmt und mit verwandten Verbindungen verglichen. Die Lumineszenzeigenschaften wurden bei 300 K und bei 4,2 K untersucht; sämtliche Verbindungen zeigen eine intensive blaugrüne Photolumineszenz. Sr2SiO3Cl2:Eu2+ zeigt Thermolumineszenz.
    Notes: Eu2SiO3Cl2 and Eu5SiO4Cl6 were prepared by reaction of EuCl2 with EuSiO3 and Eu2SiO4, respectively, Sr2SiO3Cl2: Eu2+ from mixtures of SrCO3, Eu2O3, SrCl2 · 6H2O and SiO2 under reducing conditions. The crystal structures of Eu2SiO3Cl2 [a = 1118.7(5), c = 952.6(1) pm, tetragonal, I4/m, Z = 8, R = 3.3, Rw = 3.0%] and Eu5SiO4Cl6 [a = 900.4(1), b = 1401.7(2), c = 1112.3(2) pm, β = 103.51(1)°, monoclinic, C2/c, Z = 4, R = 3.6, Rw = 2.6%] were determined from four-circle diffractometer data and compared with related compounds. The luminescence properties were investigated at 300 K and at 4.2 K; all compounds show intense bluish-green photoluminescence. Sr2SiO3Cl2:Eu2+ shows thermoluminescence.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200308
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    Synthetic and structural Studies on Organomolybdenum-Bismuth Halide Complexes (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 457-466 
    Details
    ISSN: 0044-2313
    Keywords: Organomolybdenum-bismuth halide complexes ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Untersuchungen zur Synthese und Struktur von Organomolybdän-Bismuthalogenid-KomplexenDie Reaktionen von BiBr2Ph mit Na/K[Mo(CO)3(η—C5H5)], von [BiPh{Mo(CO)3(η—C5H5)}2] mit BiBr2Ph oder BiBr3 und BiPh3 mit [Bi{Mo(CO)3(η—C5H5)}3] ergeben den Komplex [BiBrPh{Mo(CO)3(η—C5H5)}] 1, der röntgenographisch charakterisiert worden ist. Der Komplex 1 besteht aus einem Bismutzentrum mit einem Bromatom, einer Phenylgruppe und einer Mo(CO)3(η—C5H5)-Einheit. Eine intermolekulare Wechselwirkung besteht zum Bromatom eines benachbarten Moleküls, wodurch sich eine eindimensionale polymere Struktur ergibt. Bei der Umsetzung mit einer Bromidabgebenden Verbindung wird zunächst der anionische Komplex [BiBr2Ph{Mo(CO)3(η—C5H5)}2]- 3- und bei längerer Reaktion [BiBr2{Mo(CO)3(η—C5H5)}2]- 5- gebildet, das als [Ph4P]+-Salz röntgenographisch charakterisiert wurde. Der Komplex 5-, der am Bi zwei Br und zwei Mo(CO)3(η—C5H5)-Einheiten enthält, liegt in einer Struktur zwischen unvollständig trigonal-pyramidal und tetraedrisch vor. Der Komplex [PPN]2[Bi2Cl6{Mo(CO)3(η—C5H5)}2] 8 wurde ebenfalls dargestellt und röntgenographisch charakterisiert. Es liegt ein dimeres Anion vor, das aus zwei quadratischen Pyramiden mit einer gemeinsamen Kante besteht, in denen die Chloratome in der Basisebene und die zwei Mo(CO)3(η—C5H5)-Einheiten sich an den Spitzen in gegenüberliegenden Positionen befinden.
    Notes: The reactions between either BiBr2Ph and Na/K[Mo(CO)3(η—C5H5)], [BiPh{Mo(CO)3(η—C5H5)}2] and BiBr2Ph, or BiBr3 and BiPh3 and [Bi{Mo(CO)3(η—C5H5)}3] afford the complex [BiBrPh{Mo(CO)3(η—C5H5)}] 1 which has been characterised by X-ray crystallography. Complex 1 comprises a bismuth centre bonded to a bromine atom, a phenyl group and a Mo(CO)3(η—C5H5) fragment together with a longer secondary intermolecular interaction between a bromine from an adjacent molecule which results in a one-dimensional polymeric structure. Addition of a source of bromide anion to 1 affords the anionic complex [BiBr2Ph{Mo(CO)3(η—C5H5)}]- 3- although prolonged reaction results in the complex [BiBr2{Mo(CO)3(η—C5H5)}2]- 5- which was characterised by X-ray crystallography as its [Ph4P]+ salt. Complex 5- comprises a mononuclear bismuth centre bonded to two bromine atoms and two Mo(CO)3(η—C5H5) fragments in a geometry which lies between equatorially vacant trigonal bipyramidal and tetrahedral. The complex [PPN]2[Bi2Cl6{Mo(CO)3(η—C5H5)}2] 8 has also been synthesised and characterised by X-ray crystallography. A dimeric dianion is observed which can be viewed as two edge-shared square-based pyramids with chlorine atoms in the basal planes and Mo(CO)3(η—C5H5) fragments in the apical positions on opposite sides of the Bi2Cl6 plane.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200309
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  • 78
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    The Molybdenum Stannide MoSn2In memoriam Konrad Schubert (1915-1992) (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 467-470 
    Details
    ISSN: 0044-2313
    Keywords: MoSn2 ; crystal structure ; Pauli paramagnetism ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Das Molybdän-Stannid MoSn2Die Titelverbindung wurde durch Tempern von Molybdän-Pulver mit einem Überschuß von Zinn hergestellt. Einkristalle wurden durch Auflösen der zinnreichen Matrix in Salzsäure erhalten. Sie sind Pauli-paramagnetisch. Die Kristallstruktur wurde aus Einkristall-Röntgen-Diffraktometer-Daten bestimmt: P6222, a = 548,8(1) pm, c = 1417,1(2) pm, Z = 6, R = 0,036 für 18 variable Parameter und 389 Strukturfaktoren. MoSn2 ist erst der zweite Vertreter der hexagonalen Mg2Ni-Struktur. Die Beziehung der Struktur zum CuAl2-Typ wird diskutiert.
    Notes: The title compound was prepared by annealing molybdenum powder with an excess of tin. Single-crystals were obtained by dissolving the tin-rich matrix in hydrochloric acid. They are Pauli paramagnetic. The crystal structure was determined from single-crystal X-ray diffractometer data: P6222, a = 548.8(1) pm, c = 1417.1(2) pm, Z = 6, R = 0.036 for 18 variable parameters and 389 structure factors. MoSn2 is only the second representative of the hexagonal Mg2Ni-type structure. The relation of the structure to the CuAl2-type is discussed.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200310
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  • 79
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    Spektroskopische und röntgenographische Untersuchungen an Dichlormethyl-QuecksilberverbindungenProfessor Wolfgang Sawodny zum 60. Geburtstage gewidmet (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 625-631 
    Details
    ISSN: 0044-2313
    Keywords: Bis(dichloromethyl)mercury ; Dichloromethylmercuryalkyles ; synthesis ; NMR, vibrational spectra ; X-ray structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Spectroscopic and X-Ray Structural Investigations on Dichloromethyl Mercury CompoundsBis(dichloromethyl)mercury, Hg(CHCl2)2, and mixed alkyl compounds RHgCHCl2 (with R = CH3, C2H5) have been synthesized by known methods from CH2Cl2, lithium butanide and HgCl2, CH3HgCl or C2H5HgCl, respectively. The 1H-, 13C-NMR as well as the IR and Raman spectra of the liquid alkyls RHgCHCl2 and the high melting Hg(CHCl2)2 have been measured and assigned. According to the X-ray structure determination Hg(CHCl2)2 crystallizes in the monoclinic space group P21/c with 4 non-symmetric molecules per unit cell (R = 0.046).
    Notes: Bis(dichlormethyl)quecksilber, Hg(CHCl2)2, und die gemischten Alkylverbindungen RHgCHCl2 (mit R = CH3, C2H5) werden nach bekannten Vorschriften aus CH2Cl2, Lithiumbutanid und HgCl2 bzw. CH3HgCl oder C2H5HgCl synthetisiert. Die 1H- und 13C-NMR- sowie die IR- und Ramanspektren der flüssigen Alkyle RHgCHCl2 und des hochschmelzenden Hg(CHCl2)2 werden registriert und ausgewertet. Nach der Röntgenstrukturanalyse kristallisiert Hg(CHCl2)2 in der monoklinen Raumgruppe P21/c mit 4 azentrischen Molekülen in der Elementarzelle (R = 0,046).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200407
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  • 80
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    Darstellung von μ-Schwefeldisulfoniumsalzen [(CH3)2S—Sx—S(CH3)2]2+2A- (x = 1-3, A- = AsF6-, SbF6-, SbCl6-). Über die Analogie im Reaktionsverhalten zwischen Sulfanen und SulfoniumsalzenProfessor Wolfgang Sawodny zum 60. Geburtstag gewidmet (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 632-637 
    Details
    ISSN: 0044-2313
    Keywords: μ-Sulfurdisulfonium salts ; preparation ; single crystal X-ray structure ; Raman, NMR spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation of μ-Sulfurdisulfonium Salts [(CH3)2S—Sx—S(CH3)2]2+2A- (x = 1-3, A- = AsF6-, SbF6-, SbCl6-). On the Analogy of the Reactivity of Sulfanes and Sulfonium SaltsThe preparation of the μ-sulfurdisulfonium salts [(CH3)2S—Sx—S(CH3)2]2+(A-)2 with x = 1-3 and A- = AsF6-, SbF6-, SbCl6- is reported. The salts are formed by reaction of (CH3)2SH+A- and (CH3)2SSH+A- with SCl2 and S2Cl2, resp. They are characterized by vibrational spectroscopic measurements. [(CH3)2S—S2—S(CH3)2]2+(SbF6-)2 crystallizes in the space group C2/c with a = 1 884.5(7) pm, b = 1 302.8(5) pm, c = 1 477.2(5) pm, β = 98.62(3)° und Z = 8.
    Notes: Es wird über die Darstellung der μ-Schwefeldisulfoniumsalze [(CH3)2S—Sx—S(CH3)2]2+ (A-)2 mit x = 1-3 und A- = AsF6-, SbF6-, SbCl6- berichtet. Die Salze werden durch Kondensationsreaktionen von (CH3)2SH+A- und (CH3)2SSH+A- mit SCl2 bzw. S2Cl2 gebildet. Ihre Charakterisierung erfolgt schwingungsspektroskopisch. Das [(CH3)2S—S2—S(CH3)2]2+(SbF6-)2 kristallisiert in der Raumgruppe C2/c mit a = 1 884,5(7) pm, b = 1 302,8(5) pm, c = 1 477,2(5) pm, β = 98,62(3)° und Z = 8.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200408
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  • 81
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    Über die Reaktion von HCl im System HF/SbF5 und die Kristallstruktur von SbCl3F2 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 638-641 
    Details
    ISSN: 0044-2313
    Keywords: Stibiumtrichlorodifluoride ; Crystal Structure ; Raman Spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Reaction of HCl with HF/SbF5 and the Crystal Structure of SbCl3F2The reaction of HCl in HF/SbF5 solution at -78°C yields H2F+SbClF5-. At -40°C formation of SbCl3F2 was observed, which crystallizes in the tetragonal space group I-4 with a = 1 281.6(5) pm, c = 758.1(6) pm with 8 formula units per unit cell. The structure contains cis-fluorine-bridged tetramers, in which Sb has a distorted octahedral coordination.
    Notes: Die Reaktion von HCl mit einer HF/SbF5 Lösung ergibt bei -78°C H2F+SbClF5-. Bei -40°C wird die Bildung von SbCl3F2 beobachtet. Es kristallisiert in der tetragonalen Raumgruppe I-4 mit a = 1 281,6(5) pm, c = 758,1(6) pm und Z = 8. Die Struktur enthält cis-Fluor-verbrückte Tetramere, in denen Antimon eine verzerrt oktaedrische Koordinationssphäre hat.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200409
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  • 82
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    Zur Kristallchemie der Kupfer-Lanthanoid-Oxowolframate: (I) triklin-α-CuTbW2O8, (II) monoklin-CuInW2O8 und (III) monoklin-CuYW2O8 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 642-646 
    Details
    ISSN: 0044-2313
    Keywords: Copper, rare earth, tungsten, oxide ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Crystal Chemistry of Copper Rare-Earth Oxotungstates: (I): triclinic-α-CuTbW2O8, (II): monoclinic-CuInW2O8 and (III): monoclinic-CuYW2O8Single crystals of (I), (II) and (III) were prepared by recrystallisation in closed systems and examined by X-ray technique. (I): space group Cil—P1, a = 7.3080, b = 7.8945, c = 7.1476 Å, α = 115.23, β = 116.21, γ = 56.98°, Z = 2; (II): space group C2h6—C2/c, a = 9.6576, b = 11.6496, c = 4.9863 Å, β = 91.17°, Z = 4; (III): space group C2h4—P2/n, a = 10.0504, b = 5.8214, c = 5.0224 Å, β = 94.23°, Z = 2. The crystal structures are discussed with respect to calculations of the coulombterms of lattice energy and possible valence states of Cu2+ and Mo5+.
    Notes: Einkristalle von (I), (II) und (III) wurden durch Rekristallisation in geschlossenen Systemen dargestellt und röntgenographisch untersucht. Die kristallographischen Daten lauten: (I): Raumgruppe Cil—P1, a = 7,3080, b = 7,8945, c = 7,1476 Å, α = 115,23, β = 116,21, γ = 56,98°, Z = 2; (II): Raumgruppe C2h6—C2/c, a = 9,6576, b = 11,6496, c = 4,9863 Å, β = 91,17°, Z = 4; (III): Raumgruppe C2h4—P2/n, a = 10,0504, b = 5,8214, c = 5,0224 Å, β = 94,23°, Z = 2. Die Kristallstrukturen werden mit Blick auf Berechnungen der Coulombterme der Gitterenergie und mögliche Ladungen von Cu2+ und Mo5+ diskutiert.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200410
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  • 83
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    Zur Kenntnis eines Barium-Kupfer-Orthoarsenats: BaCu2(AsO4)2 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 651-654 
    Details
    ISSN: 0044-2313
    Keywords: Barium, copper, arsenic, oxide ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Crystal Structure of Barium-Copper-Orthoarsenate BaCu2(AsO4)2Single crystals of BaCu2(AsO4)2 were prepared above 1 000°C by CO2-LASER technique and investigated by X-ray structure determination. The light blue crystals show monoclinic symmetry, space group C2h5—P21/n, a = 4.752; b = 8.506; c = 8.945 Å; β = 93.49°, Z = 2. BaCu2(AsO4)2 represents a hitherto unknown structure type with Cu2+ in trigonal bipyramidal coordination. Ba2+ shows an 8 + 2 surrounding by O2- and As5+ is tetrahedrally coordinated. The crystal structure is discussed with respect to related orthophosphates and vanadates.
    Notes: Mit CO2-LASER-Technik wurden bei ca. 1 000°C Einkristalle der Verbindung BaCu2(AsO4)2 dargestellt und röntgenographisch untersucht. Die blaßblauen Kristalle haben monokline Symmetrie, Raumgruppe C2h5—P21/n, mit a = 4,752; b = 8,506; c = 8,945 Å; β = 93,49°, Z = 2. BaCu2(AsO4)2 repräsentiert einen neuen Strukturtyp, der Cu2+ in trigonal bipyramidaler Koordination zeigt. Ba2+ ist 8 + 2-fach und As5+ tetraedrisch von Sauerstoff umgeben. Die Kristallstruktur wird unter Bezug auf verwandte Orthophosphate und -vanadate diskutiert.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200412
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  • 84
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    Darstellung, Schwingungsspektren und Normalkoordinatenanalyse der Decahalogenoditechnetate(IV), [Tc2X10]2-, X = Cl, Br (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 655-658 
    Details
    ISSN: 0044-2313
    Keywords: Decachloroditechnetate(IV) ; Decabromoditechnetate(IV) ; Synthesis ; Raman, IR Spectra ; Normal Coordinate Analysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation, Vibrational Spectra and Normal Coordinate Analysis of Decahalogenoditechnetates(IV), [Tc2X10]2-, X = Cl, BrThe reaction of [TcX6]2-, X = Cl, Br, with trifluoroacetic acid yield at room temperature the edge-sharing bioctahedral anions [Tc2X10]2-, which IR and Raman spectra are assigned according to point group D2h. Using the crystal data of isostructural osmium complexes a normal coordinate analysis based on a general valence force field has been performed for [Tc2X10]2-, revealing a good agreement of the calculated frequencies with the bands observed in the IR and Raman spectra. The stronger bonding of the terminal as compared to the bridging ligands is shown by the valence force constants, fd(TcXt) 〉 Fd(TcXb).
    Notes: [TcX6]2-, X = Cl,Br, reagiert bei Raumtemperatur mit Trifluoressigsäure unter Bildung der kantenverknüpften Dioktaederanionen [Tc2X10]2-, deren IR- und Raman-Spektren entsprechend der Punktgruppe D2h zugeordnet werden. Basierend auf den kristallographischen Daten isostruktureller Osmiumkomplexe und unter Verwendung des allgemeinen Valenzkraftfeldes, werden für Decachloro- und Decabromodi-technetat(IV) Normalkoordinatenanalysen durchgeführt, die eine gute Übereinstimmung der berechneten Frequenzen mit den beobachteten Banden aus den IR- und Raman-Spektren ergeben. Die festere Bindung terminaler im Vergleich zu verbrückenden Liganden spiegelt sich in den Valenzkraftkonstanten wider: fd(TcXt) 〉 fd(TcXb).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200413
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  • 85
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    Zur Kenntnis ‘Kationen-reicher’ Tantalate Über Li7[TaO6] (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 659-664 
    Details
    ISSN: 0044-2313
    Keywords: Tantalate Li7[TaO6] ; Single Crystals ; Crystal Structure ; MAPLE ; Charge Distribution ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Tantalates ‘rich in Cations’ On Li7[TaO6]For the first time, colourless single crystals of Li7[TaO6] were grown by annealing intimate mixtures of Li2O and Ta2O5 (Li:Ta = 7,7:1) in closed Ni-cylinders (1 000°C, 156 d). [Trigonal-rhomboedral with a = 535.8(1) pm, c = 1 507.3(3) pm, c/a = 2.81/Guinier-Simon-powder data; Z = 3. Space group R3 for the part Li(1)6TaO6 and presumably P3 for Li7TaO6, including Li(2)].The crystal structure was solved by four-cycle-diffractometer data [Mo—Kα, 331 from 331 Io(hkl), R = 1.99%, Rw = 1.96%], parameters see text.The positions of anions correspond to the motif of a hexagonal closest packing of spheres, obviously deformed (with MEFIR of O2- space filling corresponds to 69.8% instead of expected 73.2%. 1/3 of the octahedron holes are ordered occupied by Ta and Li(2), 1/2 of the tetrahedral holes likewise ordered by Li(1). All polyhedra of coordination of the anions are trigonal prisms.The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, these calculated via Mean Fictive Ionic Radii, as well as charge distribution ‘CHARDI’ are calculated and discussed.
    Notes: Erstmals wurden farblose Einkristalle von Li7[TaO6] durch Tempern inniger Gemenge von Li2O und Ta2O5 (Li:Ta = 7,7:1) in einem verschlossenen Ni-Zylinder (1 000°C, 156 d) dargestellt trigonal-rhomboedrisch; a = 535,8(1) pm, c = 1 507,3(3) pm, c/a = 2,81/Guinier-Simon-Pulverdaten; Z = 3. Raumgruppe R3 für den Li(1)6TaO6-Teil; vermutlich P3 für Li(1)6Li(2)1[TaO6].Die Kristallstruktur wurde mittels Vierkreisdiffraktometerdaten [Mo—Kα, 331 von 331 Io(hkl), R = 1,99%, Rw = 1,96%] bestimmt, Parameter siehe Text.Es liegt bezüglich der Anionen im Prinzip das Motiv einer hexagonal-dichtesten Kugelpackung vor; die Verzerrung ist deutlich mit MEFIR(O2-) = 154,3 pm beträgt die Raumerfüllung 69,8% statt ideal 73,2%). Es sind 2 der 6 Oktaeder- (mit Ta bzw. Li(2)) und 6 der 12 Tetrederlücken mit Li(1) besetzt. Alle Koordinationspolyeder um O sind trigonale Prismen.Der Madelunganteil der Gitterenergie, MAPLE, und Effektive Koordinationszahlen, ECoN, diese über Mittlere Fiktive Ionenradien, MEFIR, sowie die Ladungsverteilung ‘CHARDI’ wurden berechnet und diskutiert.
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    URL: http://dx.doi.org/10.1002/zaac.19946200414
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  • 86
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    Hydrate des Cer(III)-chlorids (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 665-671 
    Details
    ISSN: 0044-2313
    Keywords: Cerium(III) chloride hydrates ; Synthesis ; Solution enthalpies ; Crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hydrates of Cerium(III) ChlorideThe thermal dehydration of CeCl3 · 7 H2O to CeCl3 gives four definite intermediates: CeCl3 · 6 H2O, CeCl3 · 3 H2O, CeCl3 · 2 H2O, CeCl3 · H2O. In the hexahydrate monomeric [CeCl2(H2O)6]+ units exist. A structure analysis of CeCl3 · 3 H2O gave an orthorhombic unit cell (S.G. Pnma; Z = 4) with a = 1 242.7(4) pm; b = 881.8(8) pm, c = 693.4(5) pm. The structure consists of [CeCl4/2Cl(H2O)3] chains, where two Ce3+ ions are connected via two chloride ions, forming bent chains in the [010] direction. The trihydrates LnCl3 · 3 H2O (Ln = Pr—Tb) are isotypic, also one modification of LaCl3 · 3 H2O. The structures of the di- and mono-hydrate are not yet known. Molar volumina and solution enthalpies in water vary linearly with the number of H2O molecules per formula unit.
    Notes: Der thermische Abbau von CeCl3 · 7 H2O zu CeCl3 verläuft über die präparativ faßbaren Hydrate CeCl3 · 6 H2O, CeCl3 · 3 H2O, CeCl3 · 2 H2O und CeCl3 · H2O. CeCl3 · 6 H2O kristallisiert isotyp zu PrCl3 · 6 H2O mit monomeren [CeCl2(H2O)6]+-Einheiten. Eine Strukturbestimmung von CeCl3 · 3 H2O Pnma; Z = 4; a = 1 242,7(4) pm; b = 881,8(8) pm, c = 693,4(5) pm ergab das Vorliegen von [CeCl4/2Cl(H2O)3]-Einheiten, die über je zwei Chlorid-Doppelbrücken zu gewinkelten Ketten in [010]-Richtung verknüpft sind. Die Trihydrate LnCl3 · 3 H2O (Ln = Pr—Tb) sind isotyp, ebenfalls eine Modifikation von LaCl3 · 3 H2O. Die Strukturen des Di- und Monohydrats sind noch unbekannt. Die Molvolumina und Lösungsenthalpien in Wasser ändern sich linear mit dem Hydratationsgrad.
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    URL: http://dx.doi.org/10.1002/zaac.19946200415
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    Beiträge zum thermischen Verhalten von Sulfaten. XII. Zum chemischen Transport von In2(SO4)3 mit Cl2 und mit HCl. Experimente und ModellrechnungenProfessor Heinz Dieter Lutz zum 60. Geburtstage gewidmet (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 672-681 
    Details
    ISSN: 0044-2313
    Keywords: Chemical transport ; In2(SO4)3 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions on the Thermal Behaviour of Sulfates XII. The Chemical Vapour Transport of In2(SO4)3 with Cl2 and HCl. Experimental Results and CalculationsBy means of CVT (T1 between 500°C and 825°C; ΔT = 50°C), well shaped crystals of anhydrous In2(SO4)3 can be grown in the less hot region of a closed silica ampoule. We investigated the dependence of the deposition rate on the variation of the concentration of the transport agent (system In2(SO4)3/Cl2) and on the variation of the transport temperature (In2(SO4)3/Cl2 as well as In2(SO4)3/HCl).A comparison of the experimental results with thermodynamical calculations shows a satisfying agreement. The influence of the variation of some additional parameters (H2O from the wall of the ampoule; ΔBH2980(In2(SO4)3)) on the deposition rate is discussed.
    Notes: Chemische Transportexperimente im Temperaturgradienten (500°C ≤ T1 ≤ 825°C; T2 〉 T1; ΔT = 50°C) ermöglichten es, gut ausgebildete Kristalle von wasserfreiem In2(SO4)3 in der weniger heißen Zone einer geschlossenen Quarzampulle phasenrein abzuscheiden. Der Einfluß einer Variation der Transportmittelkonzentration (C(Cl2)) (Cl2 eingesetzt als PtCl2)) sowie der mittleren Transporttemperatur (T̄ = 0,5 · (T2 + T1)) auf die Transportrate wurde untersucht. Weiterhin wurden Experimente mit dem Transportmittel HCl bei unterschiedlichem T̄ durchgeführt.Die Beobachtungen lassen sich durch thermodynamische Modellrechnungen befriedigend wiedergeben. Der Einfluß einer Variation weiterer Parameter (H2O aus der Ampullenwand; ΔBH2980(In2(SO4)3) auf die berechneten Transportraten wird diskutiert.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200416
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    Synthese, Eigenschaften und Kristallstrukturen von Magnesium-Diazadien-Komplexen (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 691-696 
    Details
    ISSN: 0044-2313
    Keywords: Magnesium complexes ; diazadiene ligands ; radical anions ; endiamides ; X-ray structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis, Properties and Crystal Structures of Magnesium Diazadiene ComplexesReactions of phenyl-substituted 1,4-diaza-1,3-butadienes (DAD) RN=CPh—CPh=NR (R = C6H5) 1a, C6H4-4-CH3 1b, C6H4-4-OCH3 (1c) with magnesium in dimethoxyethan lead to complexes of the type [Mg(DAD)2(DME)] 2a-c, with DAD ligands in form of radical anions. Furthermore, highly reactiv complexes of the composition [Mg(DAD)(DME)2] 3a-c could be obtained. The crystal structures of 2a, 3a and 3c were determined.
    Notes: Die Reaktion phenylsubstituierter 1,4-Diaza-1,3-butadiene (DAD) RN=CPh—CPh=NR (R = C6H5 1a, C6H4-4-CH3 1b, C6H4-4-OCH3 1c) mit Magnesium in Dimethoxyethan (DME) führt zu Verbindungen des Typs [Mg(DAD)2(DME)] 2a-c, in denen die DAD-Liganden als Radikalanionen gebunden sind. Außerdem enstehen äußerst reaktive Komplexe der Zusammensetzung [Mg(DAD)(DME)2] 3a-c. Die Kristallstrukturen von 2a, 3a und 3c wurden aufgeklärt.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200418
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  • 89
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    High-spin Mangan(II)-Phthalocyanine: Darstellung und spektroskopische Eigenschaften von Acidophthalocyaninatomanganat(II) (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 682-690 
    Details
    ISSN: 0044-2313
    Keywords: Phthalocyanines ; MnII complex ; Uv-vis-n.i.r., m.i.r., f.i.r., resonance Raman, ESR spectra ; magnetism ; cyclovoltammetry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: High Spin Manganese(II) Phthalocyanines: Preparation and Spectroscopical Properties of Acidophthalocyaninatomanganate(II)Acidophthalocyaninatomanaganese(III) is reduced by boranate, thioacetate or hydrogensulfide to yield acidophthalo-cyaninatomanganate(II) ([Mn(X)Pc2-]-; X = Cl, Br, NCO, NCS) being isolated as tetra(n-butyl)ammonium salt. In the cyclovoltammogram of [Mn(NCO)Pc2-]- the halv-wave potential for the redoxcouple MnII/MnIII is at -0.13 V, that of the first ring reduction at -0.99 V. The magnetic moments are indicative of high-spin 6A1 ground states: μMn = 5.84 (NCO), 5.78(Cl), 5.65 (Br), 5.68 μB (NCS). A Curie-like temperature dependence of μMn is observed in the region 300-30 K. Below 30 K an increase in μMn occurs due to weak intermolecular ferromagnetic coupling. The ESR spectra confirm the S = 5/2 ground state with a strong g = 6 resonance observed (AMn = 80 G) as expected for an axially distorted ligand-field. Besides the typical π-π* transitions of the Pc2--ligand several weak bands are observed in the Uv-vis-n.i.r. spectra at ca. 7.5, 9.1, 14.0 and 19.0 kK that are assigned to trip-multiplet transitions. In resonance with the band at 19.0 kK the Mn—X stretching vibration (v(MnX)) is resonance Raman enhanced: X = NCO: 319, Cl: 286, SCN: 238, Br: 202 cm-1. These vibrational frequencies are confirmed by the f.i.r. spectra. In the case of the thiocyanato-complex probably both forms of bonding of the ambident NCS-ligand are present (v(Mn—NCS): 274 cm-1). The frequencies of the vibrations of the inner (CN)8 ring are reduced by up to 20 cm-1 as compared with those of low spin MnII phthalocyanines.
    Notes: Acidophthalocyaninatomanagan(III) wird mittels Boranat, Thioacetat oder Hydrogensulfid zum Acidophthalocyaninatomanganat(II) ([Mn(X)Pc2]; X = Cl, Br, NCO, NCS) reduziert und als Tetra(n-butyl)ammoniumsalz isoliert. Im Cyclovoltammogramm von [Mn(NCO)Pc2-]- liegt das Halbstufenpotential für das Redoxpaar MnII/MnIII bei -0,13 V, das der ersten Ringreduktion bei -0,99 V. Die magnetischen Momente der Komplexe weisen auf einen high-spin 6A1-Grundzustand hin: μMn = 5,84 (NCO), 5,78 (Cl), 5,65 (Br), 5,68 μB (NCS). Die Temperaturabhängigkeit der magnetischen Suszeptibilität μMn zeigt zwischen 300 und 30 K Curie-Verhalten. Unterhalb von 30 K steigt μMn wegen schwacher intermolekularer ferromagnetischer Kopplungen an. Die ESR-Spektren bestätigen den S = 5/2-Grundzustand mit einem starken g = 6 Resonanzsignal (AMn = 80 G), wie es für ein axial verzerrtes Ligandenfeld erwartet wird. In den UV-VIS-NIR-Spektren treten neben den typischen π-π*-Übergängen des Pc2--Liganden weitere schwache Banden bei ca. 7,5, 9,1, 14,0 und 19,0 kK auf, die Trip-Multiplett-Übergängen zugeordnet werden. In den Resonanz-Raman-Spektren werden in Resonanz mit der Bande bei 19,0 kK bevorzugt die Mn—X-Valenzschwingungen (v(MnX)) angeregt: X = NCO: 319, Cl: 286, SCN: 238, Br: 202 cm-1. Die Schwingungsfrequenzen stimmen mit entsprechenden FIR-Absorptionen gut überein. Im Falle des Thiocyanato-Komplexes sind eventuell beide Bindungsformen des ambidenten NCS-Liganden präsent (v(Mn—NCS): 274 cm-1). Die Schwingungsfrequenzen des inneren (CN)8-Ringes liegen um bis zu 20 cm-1 tiefer als die von low-spin MnII-Phthalocyaninen.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200417
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    Li2H3IO6, eine neue Variante der Molybdänitstruktur (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 53-57 
    Details
    ISSN: 0044-2313
    Keywords: Dilithium trihydrogen orthoperiodate ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Li2H3IO6, a New Variant of the Molybdenite StructureLi2H3IO6 crystallizes in P61 (a = 529.70(8), c = 2 759.6(5) pm; Z = 6). The crystals are twinned by merohedry, described by m ‖ [001] and 2 ⊥ [001]. According to the results of an X-ray structure determination (2 778 diffractometer data, Rw = 0.047), Li2H3IO6 exhibits a layer structure, with oxygen forming a distorted variant of the sulfur partial structure in molybdenite (MoS2), however, with iodine and lithium in the more (Li) or less (I) distorted octahedral holes. The Li2IO6 packages are connected via strong hydrogen bonds along the edges of distorted trigonal prisms.
    Notes: Li2H3IO6 kristallisiert in der Raumgruppe P61 (a = 529,70(8), c = 2 759,6(5) pm; Z = 6). Die Kristalle sind merohedrisch verviellingt, beschrieben durch m ‖ [001] und 2 ⊥ [001]. Nach der Röntgenstrukturanalyse (2 778 unabhängige Reflexe, Rw = 0,047) liegt eine Schichtstruktur vor, in der die Sauerstoffatome eine verzerrte Variante der Schwefelteilstruktur von Molybdänit (MoS2) ausbilden, die Kationen besetzen die mehr (Li) oder weniger (I) verzerrten Oktaederlücken. Die Li2IO6-Schichtpakete werden entlang der Kanten der verzerrten trigonalen Prismen durch Wasserstoffbrückenbindungen miteinander verknüpft.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200109
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    Zur Reaktion von 2,2′-Dilithiumbiphenyl mit SmBr3 Die Struktur von [(C24H16)SmBr(thf)2]2 · [C24H14] (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 703-706 
    Details
    ISSN: 0044-2313
    Keywords: SmIII dimeric complex ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Reaction of Dilithiumbiphenyl with SmBr3. The Crystal Structure of [(C24H16)SmBr(thf)2]2 · [C24H14]In THF SmBr3 forms with [(biph)Li2] the dimeric complex [(quaph)SmBr(thf)2]2 · [C24H14]. The structure was characterized by X-ray single crystal structure analysis (space group P1 (No. 2), Z = 1, a = 943.3(6) pm, b = 1 350.3(1) pm, c = 1 599.9(9) pm, α = 64.99(5)°, β = 89.02(5)°, γ = 73.02(6)°). The Sm iones are bridged by two Br iones. Coordination by one quaph and THF ligands leads to distorded octahedra coordination of the Sm iones. Additionally crystallizes one molecule dibenzonaphthacene.
    Notes: SmBr3 reagiert mit [(biph)Li2] in THF zu dem zweikernigen Komplex [(quaph)SmBr(thf)2]2 · [C24H14]. Der Aufbau konnte durch eine Kristallstrukturanalyse geklärt werden (Raumgruppe P1 (Nr. 2), Z = 1, a = 943,3(6) pm, b = 1 350,3(1) pm, c = 1 599,9(9) pm, α = 64,99(5)°, β = 89,02(5)°, γ = 73,02(6)°). Die Sm-Ionen werden durch zwei Br-Ionen verbrückt. Durch zusätzliche Koordination eines quaph- und zweier THF-Liganden ist jedes Sm-Ion verzerrt oktaedrisch koordiniert. Zusätzlich kristallisiert ein Molekül Dibenzonaphthacen mit aus.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200420
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    Synthesen und Strukturen funktionell substituierter Ferrocene (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 716-722 
    Details
    ISSN: 0044-2313
    Keywords: N,O-Bis(trimethylsilyl)ferrocenylimidate ; E,Z-(Ferrocenyl-trimethylsiloxymethyliden)trimethylsilylphosphane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses and Structures of functional substituted FerrocenesSubstituted ferrocenes have been prepared using carbonic acid chloride of ferrocene. New pathways have been found reacting the acid chloride with sodium hexamethyldisilazane and tris(trimethylsilyl)phosphane, respectively. The compounds FecC(OSiMe3)N(SiMe3) (Fec = C5H5FeC5H4) 1 and FecC(OSiMe3)P(SiMe3) 2 have been obtained and characterized by X-ray single crystal structure analysis. Experiments for the preparation of FecCP 3 are reported.
    Notes: Zur Synthese funktionell substituierter Ferrocene wurde Ferrocencarbonsäurechlorid mit Natriumhexamethyldisilazan und Tris(trimethylsilyl)phosphan umgesetzt und das Imidat FecC(OSiMe3)N(SiMe3) (Fec = C5H5FeC5H4) 1 und das Phosphaalken FecC(OSiMe3)P(SiMe3) 2 erhalten. Versuche zur Darstellung von FecCP 3 werden mitgeteilt. Von den Verbindungen 1 und 2 konnten Einkristall-Röntgenstrukturanalysen angefertigt werden.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946200422
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    Über Chalkogenolate. 203. Derivate der Selendithioallophansäure 2. Darstellung und Eigenschaften von Alkylestern (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 730-732 
    Details
    ISSN: 0044-2313
    Keywords: Alkyl esters of selenodithioallophanic acid ; synthesis ; electron absorption spectra ; infrared spectra ; nuclear magnetic resonance spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Chalcogenolates. 203. Derivatives of Selenodithioallophanic Acid. 2. Preparation and Properties of Alkyl EstersSynthesis and properties of selenodithioallophanic acid esters H2N—CSe—NH—CS—SR where R = CH3, C2H5 as well as their characterization by means of electron absorption, infrared, and nuclear magnetic resonance spectra are described.
    Notes: Synthese und Eigenschaften von Alkylestern der Selendithioallophansäure H2N—CSe—NH—CS—SR mit R = CH3, C2H5 sowie deren Charakterisierung durch Elektronenabsorptions-, Infrarot- und kernmagnetische Resonanzspektren werden beschrieben.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/zaac.19946200424
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    Dimethylzinndithioquadratat: Die Kristallstruktur des Benzol-Solvats und des Dimethylsulfoxid-Addukts (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 723-729 
    Details
    ISSN: 0044-2313
    Keywords: Dimethyltin dithiosquarate benzene solvate ; Dimethyltin dithiosquarate-dimethylsulfoxide adduct ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dimethyltin Dithiosquarate: The Crystal Structure of the Benzene Solvate and of the Dimethylsulfoxide Adduct(CH3)2SnS2C4O2 · 1/3 C6H6 (I) crystallizes in the orthorhombic space group Pnma. a = 14.393(2), b = 21.668(3), c = 10.424(1) Å, Z = 12.(CH3)2SnS2C4O2 · (CH3)2SO (II) is monoclinic, space group P21/n, a = 9.918(5), b = 12.028(6), c = 12.223(6) Å, β = 108.82(3)°, Z = 4.In I there are two independent dimethyltin dithiosquarate molecules. But in both molecules the Sn atoms display weak coordinative bonds to two O atoms of adjacent dithiosquarate groups. The distances amount 2.873 Å (2×), resp. 2.678 and 2.831 Å. The coordination number of tin becomes 6 and the structure gets connected in three dimensions.In II dimethylsulfoxide is bound with the O atom to Sn (2.345 Å) and the result is a distorted trigonal bipyramid. There a more distant O atom (2.944 Å) leads to a connection of the molecules to a ribbon. The changes of the geometrical parameters are described, which result from the progressive approach of the one O atom.
    Notes: (CH3)2SnS2C4O2 · 1/3 C6H6 (I) kristallisiert in der orthorhombischen Raumgruppe Pnma; a = 14,393(2); b = 21,668(3); c = 10,424(1) Å; Z = 12.(CH3)2SnS2C4O2 · (CH3)2SO (II) ist monoklin, Raumgruppe P21/n; a = 9,918(5); b = 12,028(6); c = 12,223(6) Å; β = 108,82(3)°; Z = 4.In I liegen zwei kristallographisch unabhängige Dimethyl-zinndithioquadratat-Moleküle vor. Bei beiden weisen jedoch die Sn-Atome schwache koordinative Bindungen zu zwei O-Atomen benachbarter Dithioquadratat-Gruppen auf. Die Abstände betragen 2,873 Å (2×) bzw. 2,678 und 2,831 Å. Dadurch erhält Zinn die Koordinationszahl 6, und es ergibt sich eine dreidimensional vernetzte Struktur.In II ist Dimethylsulfoxid über das O-Atom an Sn gebunden (2,345 Å), und es liegt eine verzerrte trigonale Bipyramide vor. Ein weiter entferntes O-Atom (2,944 Å) bewirkt hier die Vernetzung der Moleküle zu einem Band. Die Veränderungen der geometrischen Parameter als Folge der fortschreitenden Annäherung des einen O-Atoms werden beschrieben.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200423
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    Chemischer Transport und Sublimationsverhalten von CrBr3  -  Experimente und Modellrechnungen (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 73-80 
    Details
    ISSN: 0044-2313
    Keywords: Chromium bromide ; chemical vapor transport ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Chemical Transport and Sublimation of CrBr3  -  Experiments and Model CalculationsThe migration of CrBr3 in the presence of high concentrations of bromine (for example D(Br2) = 0,05 mmol/ml; closed silica ampoules) in the investigated temperature range (T̄ = 625°C to 875°C; T̄ = 50°C) is a result from the endothermic reaction \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c}{(1)} & {{\rm CrBr}_{{\rm 3,s}} + 1/2{\rm Br}_{{\rm 2,g}} = {\rm CrBr}_{4,{\rm g}}}\end{array} $$\end{document} The chemical transport of CrBr3 is superimposed with the sublimation. With low concentrations of D(Br2) and high temperatures T̄ is the sublimation decisive participated. This is a result of the homogenous equilibrium between CrBr3,g and CrBr4,g (2a) \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c}{(2)} & {{\rm CrX}_{{\rm 4,g}} = {\rm CrX}_{{\rm 3,g}} + 1/2\,{\rm X}_{{\rm 2,g}},} & {({\rm a)\,X} = {\rm Br,}} & {{\rm (b)\,X} = {\rm Cl}}\end{array} $$\end{document} The reaction (2a) in comparison with the chemical transport of CrCl3 with Cl2 (Gl. (2b)) is more shifted to CrBr3,g.
    Notes: CrBr3 wandert in einer geschlossenen Ampulle bei hohen Transportmitteldichten (z. B. D(Br2)  -  0,05 mmol/ml) im untersuchten Temperaturbereich (T̄ = 625°C bis 875°C; T̄ = 50°C) von der heißeren (T2) in die weniger heiße Zone (T1) über das endotherme Transportgleichgewicht \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c}{(1)} & {{\rm CrBr}_{{\rm 3,s}} + 1/2{\rm Br}_{{\rm 2,g}} = {\rm CrBr}_{4,{\rm g}}}\end{array} $$\end{document} Der chemische Transport von CrBr3 wird von einer Sublimation überlagert, die bei niedrigeren Transportmitteldichten D(Br2) und höherer Temperatur T̄ maßgeblich beteiligt ist, wie die Lage des homogenen Gasphasengleichgewichts (2a) zwischen CrBr3,g und CrBr4,g zeigt. \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c}{(2)} & {{\rm CrX}_{{\rm 4,g}} = {\rm CrX}_{{\rm 3,g}} + 1/2\,{\rm X}_{{\rm 2,g}},} & {({\rm a)\,X} = {\rm Br,}} & {{\rm (b)\,X} = {\rm Cl}}\end{array} $$\end{document} Gleichgewicht (2a) liegt im Vergleich zum chemischen Transport von CrCl3 mit Cl2 (Gl. (2b)) mehr auf der Seite von CrBr3,g.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200112
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    Die Elektronische Struktur von Nb3Br8 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 81-84 
    Details
    ISSN: 0044-2313
    Keywords: Nb3Br8 ; electronic structure ; molecular orbitals ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Electronic Structure of Nb3Br8The bonding in Nb3Br8 was investigated with the aid of extended Hückel and molecular orbital calculations to gain some understanding concerning stability and possible chemical altering. Seven electrons occupy metal - metal bonding states of a Nb3Br8 unit. Six of them are responsible for strong σ bonds within the Nb3 cluster. One to two additional electrons may be incorporated to occupy a1 orbitals, which slightly increase the bonding in a Nb3 cluster, rather than between adjacent clusters.
    Notes: Die Bindungsverhältnisse in Nb3Br8 werden mittels Extended-Hückel- und Molekülorbital-Rechnungen untersucht, um hieraus Hinweise auf die Stabilität und mögliche chemische Modifizierbarkeit zu erhalten. Sieben Elektronen sind den Metall - Metall-bindenden Zuständen einer Nb3Br8-Einheit zuzurechnen. Sechs davon sind für starke σ-Bindungen in den Nb3-Clustern verantwortlich. Ein bis zwei zusätzliche Elektronen können in den a1-Orbitalen untergebracht werden, die sich innerhalb eines Nb3-Clusters schwach bindungsverstärkend auswirken, nicht aber zwischen benachbarten Clustern.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200113
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    Synthese und Eigenschaften von molekularen Leitern auf der Basis von dmit-isologen Chelaten Kristall- und Molekülstruktur des Tetramethylammonium-bis-[bis-(1,3-dithiol-2-selon-4,5-diselenolato)nickelat]; [(CH3)4N][Ni(dsise)2]2 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 90-100 
    Details
    ISSN: 0044-2313
    Keywords: Dichalcogenolenchelates ; conducting materials ; x-ray ; EPR ; dmit isologues ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses and Properties of Molecular Conductors based on dmit isologous Chelates. Crystal and Molecular Structure of Tetramethylammonium-bis-[bis(1,3-dithiole-2-selone-4,5-diselenolato)nickelate]; [(CH3)4N] [Ni(dsise)2]2Syntheses and properties of dichalcogenolate chelates of the general type [(CH3)4N]n[ML2] (n ≤ 2; M = Ni, Pd, Pt); L = dmit (1,3-dithiole-2-thione-4,5-dithiolate), dmise (1, 3-dithiole-2-selone-4,5-dithiolate), dsit (1, 3-dithiole-2-thione-4,5-diselenolate), dsise (1, 3-dithiole-2-selone-4,5-diselenolate), dsis (1, 3-diselenole-2-selone-4,5-diselenolate) are reported. The effects of the chalcogen atom variation in these chelates are discussed by using UV/VIS, IR, EPR, cyclovoltammetric and conductivity data. The x-ray structure of [(CH3)4N][Ni(dsise)2]2 (space group Pccn, a = 7.427(1), b = 39.144(5), c = 11.836(1) Å) and the conductivity of the crystal (12 S cm-1 at room temperature) are given.
    Notes: Synthese und Eigenschaften von Dichalkogenolat-Chelaten vom Typ [(CH3)4N]n[ML2] mit n ≤ 2; M = Ni, Pd, Pt und L = dmit (1, 3-Dithiol-2-thion-4,5-dithiolat), dmise (1,3-Dithiol-2-selon-4,5-dithiolat), dsit (1,3-Dithiol-2-thion-4,5-diselenolat), dsise (1,3-Dithiol-2-selon-4,5-diselenolat) und dsis (1, 3-Diselenol-2-selon-4, 5-diselenolat) werden beschrieben. Anhand von UV/VIS-, IR-, EPR-, cyclovoltammetrischen und Leitfähigkeitsuntersuchungen werden die Auswirkungen der Chalkogenvariation in den Chelaten diskutiert. Die röntgenkristallographischen Daten von [(CH3)4N] [Ni(dsise)2]2 (Raumgruppe Pccn, a = 7,427(1), b = 39,144(5), c = 11,836(1) Å) und die Kristalleitfähigkeit (12 S cm-1, Raum-temperatur) werden vorgestellt.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200115
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  • 98
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    Na2[Pr4O2]Cl9 und K2[Pr4O2]Cl9, die ersten reduzierten quaternären Praseodymchloride mit anti-SiS2-analogen [Pr4/2O]-Ketten (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 85-89 
    Details
    ISSN: 0044-2313
    Keywords: Praseodymium ; Reduced Chlorides ; Synthesis ; Crystal Structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Na2[Pr4O2]Cl9 and K2[Pr4O2]Cl9, the First Reduced Quaternary Praseodymium Chlorides with Anti-SiS2 Analogous [Pr4/2O] ChainsThe compounds A2[Pr4O2]Cl9 (A = Na, K) are the first reduced quaternary praseodymium chlorides with anti-SiS2 analogous [Pr4/2O] chains. Synthesis took place in the temperature range from 900 to 600°C in silica-jacketed niobium containers from Pr metal, PrCl3, PrOCl and NaCl (KCl) as starting materials. The X-ray structure analysis of a single crystal of Na2[Pr4O2]Cl9 (monoclinic, P21/m (No. 11), Z = 2, a = 812.2(2) pm, b = 1 134.1(2) pm, c = 937.6(2) pm, β = 106.51(2)°, R = 0.048, Rw = 0.037) exhibits trans-edge connected chains of [Pr4/2O] tetrahedra running along [001] which are connected by surrounding common chloride ions forming layers parallel to (001). These layers are connected by further chloride ions to a three-dimensional network. The sodium ions surrounded by a heavily distorted octahedron of chloride ions are placed between the layers. The X-ray structure analysis of a single crystal of the otherwise isotypic K2[Pr4O2]Cl9 (monoclinic, P21/m (No. 11), Z = 2, a = 820.6(2) pm, b = 1 133.2(4) pm, c = 949.2(3) pm, β = 103.94(2)°, R = 0.073, Rw = 0.054) shows that potassium is coordinated by nine chloride ions.
    Notes: Erstmals erhalten wurden reduzierte quaternäre Praseodymchloride mit anti-SiS2-analogen [Pr4/2O]-Ketten vom Typ A2[Pr4O2]Cl9 (A = Na, K). Die Synthese erfolgt im Temperaturbereich von 900 bis 600°C in quarzglasummantelten Niobampullen aus Pr-Metall, PrCl3, PrOCl und NaCl bzw. KCl. Die Röntgenstrukturanalyse an einem Einkristall von Na2[Pr4O2]Cl9 (monoklin, P21/m, Z = 2, a = 812,2(2) pm, b = 1 134,1(2)pm, c = 937,6(2)pm, β = 106,51(2)°, R = 0,048, Rw = 0,037) zeigt, daß die entlang [010] verlaufenden, über gemeinsame transständige Pr—Pr-Kanten zu Ketten verknüpften [Pr4/2O]-Tetraeder in der (001)-Ebene über umgebende, gemeinsame Chloratome zu Schichten verknüpft sind, die ihrerseits über Chloratome zu einer dreidimensionalen Struktur verbunden sind. Zwischen den Schichten befindet sich Na+, stark verzerrt oktaedrisch von Cl- umgeben. Die Röntgenstrukturanalyse an einem Einkristall des ansonsten isotypen K2[Pr4O2]Cl9 (monoklin, P21/m (Nr. 11), Z = 2, a = 820,6(2)pm, b = 1 133,2(4)pm, c = 949,2(3)pm, β = 103,94(2)°, R = 0,073, Rw = 0,054) zeigt, daß K+ dort von 9 Cl- umgeben ist.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946200114
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  • 99
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    CO2-Transfer durch Metallphenolate: N-Methyl-ε-carolactam/Natriumphenolat als selektives Reagenz für Carboxylierungsreaktionen (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 101-106 
    Details
    ISSN: 0044-2313
    Keywords: Sodium phenoxide ; CO2 transfer ; carboxylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: CO2 Transfer by Metal Phenoxides: N-Methyl-ε-caprolactam/Sodium Phenoxide as a Selective Reagent for Carboxylation ReactionsCarboxylation reaction of aceton and other substrates with active C—H bonds can be carried out selectively by complexes of sodium phenoxide with N-methyl-ε-caprolactam („NMC“) and CO2. With aceton 3-keto-glutaric acid is formed in 85% yield upon hydrolysis. X-Ray structural analysis of the tetrameric [(NMC)Na(OPh)]4 shows that sodium- and oxygen ions of the phenoxide occupy the positions of a cubus. NMC acts as monodendate ligand, the oxygen atoms of the phenoxide are tridendate bridging ligands. The lithium compound has a similar structure. The complex solved in NMC takes up 0.5 mol CO2 per mol Natrium which at room temperature and normal pressure is transformed to aceton.
    Notes: Carboxylierungsreaktionen von Aceton und anderen Substraten mit aktiven C—H-Bindungen können selektiv mit Komplexen des Natriumphenolats mit N-Methyl-ε-caprolactam („NMC“) und CO2 durchgeführt werden. Mit Aceton entsteht in 85% Ausbeute nach Hydrolyse 3-Ketoglutarsäure. Die Röntgenstrukturanalyse des tetrameren Komplexes [(NMC)Na(OPh)]4 zeigt, daß Natrium- und Phenolatsauerstoffionen die Ecken eines Würfels besetzen.Na1 hat die Koordinationszahl 4. NMC fungiert als einzähliger Ligand, die Sauerstoffatome des Phenolats sind dreizählige Liganden. Die Lithiumverbindung hat eine vergleichbare Struktur. Der Komplex nimmt pro Mol Natriumion in NMC 0,5 Mol CO2 auf, das bei Raumtemperatur und Normaldruck auf Aceton übertragen wird.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946200116
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  • 100
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    Synthese und Kristallstruktur von Cu4[PhN3C6H4N3(H)Ph]4(μ2-O)2, einem vierkernigen Kupfer(II)-Komplex mit 1-Phenyltriazenido-2-phenyltriazenobenzol als Ligand (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 107-111 
    Details
    ISSN: 0044-2313
    Keywords: Tetrameric copper(II) complex ; μ2-oxo ligand ; 1-phenyltriazenido-2-phenyltriazeno benzene ligand ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Crystal Structure of Cu4[PhN3C6H4N3(H)Ph]4(μ2-O)2, a Tetranuclear Copper(II) Complex with 1-Phenyltriazenido-2-phenyltriazeno-benzene as LigandCu4[PhN3C6H4N3(H)Ph]4(μ-O)2 (1) results from the reaction of an aqueous solution of [Cu(NH3)4]2+ with 1,2-bis(phenyltriazeno)benzene in ether. 1 crystallizes in the orthorhombic space group Pba2 with the lattice parameters a = 1661.5(5), b = 1914.7(7), c = 1269.2(5) pm; Z = 2. In the tetrameric complex with the symmetry C2 the Cu2+ cations form a tetrahedron (Cu—Cu: 298.3(1)-337.1(1) pm). The μ2-oxo ligands occupy the twofold axis and bridge two opposite edges of the Cu4 tetrahedron (Cu—O: 190.0(3) and 192.5(4) pm). The 1-phenyltriazenido-2-phenyltriazeno benzene anions bridge two Cu2+ ions chelating one metal ion and coordinating monodentate the neighbouring one (Cu—N: 191.0(5)-204.1(4) pm).
    Notes: Cu4[PhN3C6H4N3(H)Ph]4(μ-O)2 (1) entsteht bei der Umsetzung einer wäßrigen Lösung von [Cu(NH3)4]2+ mit 1,2-Bis(phenyltriazeno)benzol in Ether. 1 kristallisiert orthorhombisch in der Raumgruppe Pba2 mit den Gitterkonstanten a = 1661,5(5); b = 1914,7(7); c = 1269,2(5) pm; Z = 2. Im tetrameren Komplex mit der Symmetrie C2 bilden die Cu2+-Ionen ein Tetraeder (Cu—Cu: 298,3(1)-337,1(1) pm). Die μ2-Oxoliganden liegen auf der C2-Achse und überbrücken zwei gegenüberliegende Tetraederkanten (Cu—O: 190,0(3) und 192,5(4) pm). Die 1-Phenyltriazenido-2-phenyltriazeno-benzol-Anionen verbrücken benachbarte Cu2+-Ionen, die sie einerseits chelatisierend und andererseits einzähnig koordinieren (Cu—N: 191,0(5)-204,1(4) pm).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946200117
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