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  • 1995-1999
  • 1990-1994  (290)
  • 1965-1969
  • 1990  (290)
  • Physical Chemistry  (232)
  • Industrial Chemistry
  • Nuclear reactions
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  • 1995-1999
  • 1990-1994  (290)
  • 1965-1969
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  • 1
    Electronic Resource
    Electronic Resource
    Sensitivity analysis of catalytic conversion of n-C6 (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 277-288 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The present paper is a case study of an application of sensitivity analysis in chemical kinetics. Emphasis is laid upon chemical interpretation of sensitivity information and on identification of the most important model important model parameters. The kinetic model for reforming of C6 hydrocarbons proposed by Mobil [14] is extended to the analysis of the behavior of n-hexane conversion in an adiabatic reactor. The importance of six initial conditions (feed composition and initial temperature) is analyzed by the computation of normalized first order sensitivity gradients (y1o/y) (δyi/δy1o). The relative importance of 21 model parameters αj is estimated by the computation of normalized sensitivity gradients of the type (αj/yi) (δyi/δαj). The influence of the decisive model parameters ΔH6o and ΔH3o (activation enthalpies of benzene hydrogenation and methyl cyclopentane isomerization, respectively) as well as operating parameters is presented. The problem of uncertainly in the value of ΔH6o and its influence on the model solution is also sown. Finally, some advantages of the application of normalized gradients of the explanation of process behavior are discussed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130138
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  • 2
    Electronic Resource
    Electronic Resource
    Modeling and simulation of reactions involving bifunctional catalysts (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 319-322 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model based on experimental results is set up for a typical model reaction of hydrocarbon reforming, namely the dehydroisomerization of methyl cyclopentane. Computer simulations shows that the existing theory about the reaction path of hydrocracking reactions involving bifunctional catalysts may be only partly valid.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130143
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  • 3
    Electronic Resource
    Electronic Resource
    Inertial deposition on front and rear sides of ribbons at intermediate and high reynolds numbers (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 322-327 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Deposition of particles from gas flows on ribbons in normally expected on the front side. Collision efficiencies of ribbons are presented for this case, obtained by means of single particle trajectory computation, which is based on numerically determined flow fields in the Reynolds number range between 2 and 50 and on the potential flow model. Further, it is shown, that deposition of particles on the rear side can be caused by eddylike motion of the fluid in the wake of the ribbon. For this to occur, two conditions must be fulfilled: the free shear layer between the wake and the outer flow must be turbulent to cause lateral transfer of particles into the wake and the Stokes number may not exceed 0.5.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130144
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  • 4
    Electronic Resource
    Electronic Resource
    Mixing in continuous DTB and FC crystallizers (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 349-356 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Owing to imperfect mixing, the theoretical prediction of CSD for an MSMPR crystallizer deviates from the experimental results. In the present work, different modelling approaches were adopted to account for incomplete mixing in DTB and FC crystallizers. For DTB crystallizers, compartmental model, based on an earlier work of Nyvlt et al. has been proposed. For FC crystallizers, a mixed model comprising perfectly mixed and plug flow regimes has been put forward. This is based on the tracer response studies reported by de Jong. Predicted results were compared with experimental data of Bennett and van Buren for continuous urea crystallizers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130148
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  • 5
    Electronic Resource
    Electronic Resource
    Selection and design of aerobic bioreactorsModified version of a paper presented by A. Mersmann at the “Jahrestreffen der Verfahrens-Ingenieure”, Berlin, September 27 to 29, 1989.Dedicated to Professor Kurt Dialer on the occasion of his 70th birthday (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 357-370 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Compared to chemical reactors, there are additional requirements to be considered when selecting and designing a bioreactor. The cultivated organisms and most of the desired products are to a greater or lesser extent sensitive to temperature, pH and Shear stress. Furthermore, sterilization often plays an important role in maintaining a monoseptic process. Many design procedures for chemical reactors can be applied but requirements which are relevant to the biological system are sometimes decisive. Consequently, it is useful to first consider the essential features of the organisms with respect to the selection and design of bioreactors. Attention must be paid to the fermentation medium because its flow behaviour can range from slightly viscous and Newtonian to highly viscous, non-Newtonian. Many papers deal with low viscosity fermentation broths [1-5]. However, little is known about the design of bioreactors for highly viscous non-Newtonian liquids. Fundamentals for the design of bioreactors are presented. It has been attempted to apply theoretical equations suitable for both, low viscosity Newtonian and high viscosity non-Newtonian fermentation broths. Apart from the calculation procedure for the OTR-values, the difference between global and local values within bioreactor is demonstrated by means of velocity and shear stress profiles. Special requirements for bioreactors such as prevention of excessive foaming, shear sensitivity of micro-organisms and cell-lines and effective sterilization are also discussed.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130149
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  • 6
    Electronic Resource
    Electronic Resource
    Monte carlo simulation of transient CSD in a continuous crystallizer (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 392-397 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A Monte Carlo simulation scheme is proposed for transient crystal size distribution in a continuous crystallizer. The suggested scheme can taken into account dispersion effects of growth rate, shape factor and birth size on crystal size distribution. This method is simple and more versatile than solution of the number balance equation or the finite-state Markov chain model. The proposed algorithm of the process has a very simple structure and can be easily implemented on a personal computer. The present contribution is extension of an earlier work of Sen Gupta and Dutta.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130153
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  • 7
    Electronic Resource
    Electronic Resource
    Fluid dynamics of pulsed sieve plate extraction columnsPaper presented by M. Lorenz at the “Jahrestreffen der Verfahrens-In-genieure”, Berlin, September 27 to 29, 1989. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 411-422 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The presented contribution reports on comprehensive hydrodynamic investigations in two pulsed sieve-plate extraction columns (PSE) on a pilot scale. The experiments were conducted with three different sieve plate geometries employing test systems recommended by EFCE, under varying pulsation conditions and throughputs. The results of the investigation add to the existing knowledge of relationships between hydrodynamic parameters, drop size, hold-up, flooding throughput and mixing and operating parameters. They also provide useful information for scale up, selection of sieve-plate geometry, most favorable operating range, and constructive design of equipment. On the basis of measurements, analytical methods are recommended for prediction of PSE hydrodynamics.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130156
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  • 8
    Electronic Resource
    Electronic Resource
    Modern carbon fibres from polyacrylonitrile (PAN)-polyheteroaromatics with preferred orientationDedicated to Professor Hansjörg Sinn on the occasion of his 60th birthday (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 41-49 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This contribution presents the mechanical data of high performance carbon fibres currently available on the market, based on experimental studies on stabilization and pyrolysis of PAN (SAF) from Courtaulds. The effects of stabilization and carbonization temperatures on the properties as well as on the ultra- and crystalline structures of the fibres are shown in more detail.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130107
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  • 9
    Electronic Resource
    Electronic Resource
    Residence time distribution and hold-up in a cocurrent upflow packed bed reactor at elevated pressureDedicated to Professor Ewald Wicke on the occasion of his 75th birthday (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 27-40 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The residence time distribution in liquid phase was measured in a cocurrent upflow packed bed reactor for the system methanol-hydrogen at low Reynolds numbers and at elevated pressure. The plug flow with axial dispersion model was used to describe mixing in the system. The imperfect pulse method was used to measure the system response to a tracer pulse input. The parameters were calculated using the weighted moments method. The influence of the weighting factor was investigated. The experimental and theoretical outputs, as calculated by convolution, agreed very well. Different types of correlations were used for the Bodenstein number and liquid hold-up. From these correlations, the optimal one was selected for each parameter. A comparison was made between the ordinary moments and the weighted moments methods which led to the conclusion that the latter method is superior with respect to the accuracy of the estimated parameters and therefore strongly recommended.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130106
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  • 10
    Electronic Resource
    Electronic Resource
    Study on dynamic behaviour of thermally coupled distillation processes (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 119-125 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A dynamic mathematical model has been developed which is suitable for thermally coupled distillation processes. An algorithm known as the equation-decoupled method was used for simulation. EPISODE software and LU decomposition method were adopted to solve the ordinary differential and algebraic equations of the model, respectively. The initial conditions, viz. a solution for the steady state of the process in dynamics simulation were obtained by means of modified Naphtali-Sandholm algorithm. Research on the dynamic behaviour of thermally coupled distillation processes was carried out on two examples. It was found, via the dynamic simulation, that a disturbance in the distribution of vapour coupled stream has a large effect on the composition of vapour side withdrawal and, similarly, for liquid coupled stream, on that of liquid side withdrawal when the fraction of side withdrawal is fixed, and a smaller effect when the quantity of side withdrawal is fixed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130116
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  • 11
    Electronic Resource
    Electronic Resource
    Growth rate dispersion in a continuous sucrose crystallizer and its effect on CSD (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 196-202 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A Random Crystal Growth (RCG)model is proposed to predict CSD in a continuous MSMPR crystallizer when the crystals exhibit growth rate dispersion. RCG model links two well-known models of growth rate dispersion, namely the Random Fluctuation (RF) and Constant Crystal Growth (CCG) Models. Monte Carlo simulation has been employed to solve the model equations. Predicted results are compared with experimental CSD data on sucrose reported by Bennett.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130126
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  • 12
    Electronic Resource
    Electronic Resource
    Simple new formulae for efficiency and mean temperature difference in heat echangersPaper based on a poster presentation at the “Jahrestreffen der Ver-fahrens-Ingenieure”, Berlin, Sept. 26 to 29, 1989 (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 237-241 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The well-known formulae for efficiency and mean temperature difference of a heat exchanger as functions of its numbers of transfer units, or dimensionless lengths, can be written in a more compact form by introducing the auxiliary function ϕ(x) = x/(1 - e-x). The resulting new formulae show a number of advantages: They are shorter, easier to memorize, and in many cases the limiting values can be seen more directly. They may therefore contribute to easier and faster heat exchanger design, and to reduced probability of errors in the relevant calculations.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130132
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  • 13
    Electronic Resource
    Electronic Resource
    Deasphaltization and demetalling of heavy crude oils and distillation residues with CO2 (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 258-264 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Deasphaltization of heavy crude oils and distillation residues may reduce the metal content of these oils to such an extend that the upgrading of deasphaltized oil in a catalytic process becomes economically feasible. Experimental results of deasphaltization of Boscan crude from Venezuela, using subcritical and supercritical carbon dioxide as deasphaltizing agent, are presented. Deasphaltization and demetalling with CO2 in the supercritical state is more effective. Under favorable conditions, the deasphaltized oil contains practically no asphaltenes and the metal content is reduced by 690 wt-%. The influence of n-heptane or n-pentane addition to the crude, which lowers viscosity and promotes flocculation, is also discussed. Furthermore, a multistage deasphaltization process is more efficient than a single stage process.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130135
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  • 14
    Electronic Resource
    Electronic Resource
    Measurements with multi-point microprobes: Effect of suspended solids on the hydrodynamics of bubble columns for application in chemical and biotechnological processesPaper presented by Chr. Wolff at the “GVC Working Party on Multiphase Flow”, Schliersee, Fed. Rep. Germany, April 13 to 15, 1988. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 172-184 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Many experimental studies reveal that suspended solids considerably alter the coalescence behaviour and hydrodynamic functions of wo-phase flow. But no systematic efforts have yet been undertaken to separate the effects of different particle properties on local gas hold-up, bubble size and interfacial area gas/liquid. The aim of this paper is to present the local values of these parameters in three-phase fluidized beds of different solids, using miniaturized optical fiber and conductivity needle probes. It is shown that particle concentration, size and, in particular, density are decisive for the change in coalescence behaviour. Ranges of normal (ϱS 〉 ϱL) and inverse fluidization (ϱS 〈 ϱL) must be distinguished and the flow regime also exerts a strong influence on the interactions between the dispersed phases, the transition point itself being a function of particle properties can be observed, This effect is evaluated for different column diameters, between 0.1 and 0.3 m.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130124
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  • 15
    Electronic Resource
    Electronic Resource
    Agitation of aerated emulsionsPaper presented by T. Schneider at the internal meeting of the GVC-working party “Mixing” at Breisach, West-Germany, 3 May, 1988. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 209-213 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Aerated emulsions are gaining significance in fermentation as well as in inorganic and organic chemistry. In these processes, liquid-liquid mass transfer can be the limiting step. Therefore, the effect of gassing rate on droplet size was investigated as a function of dispersed liquid phase concentration and power input in different vessels. At high power inputs, the droplet size decreased. With increasing dispersed phase concentration and gassing rate, the droplet size increased and its dependence on power input subsided.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130128
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  • 16
    Electronic Resource
    Electronic Resource
    Masthead (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990) 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    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.270130101
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  • 17
    Electronic Resource
    Electronic Resource
    Mass transfer in countercurrent and cocurrent bubble columns (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 113-118 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The hydrodynamic and mass transfer characteristics in countercurrent, cocurrent and liquid batch operations with various Newtonian liquids were studied experimentally using the same bubble column. Taking the effect of gas sparger geometries, operating variables and liquid properties into account, empirical correlations were obtained for the gas hold-up and the volumetric liquid-phase mass transfer coefficient.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130115
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  • 18
    Electronic Resource
    Electronic Resource
    Critical temperatures and pressures and high temperature vapour pressures of seven alcohols (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 125-130 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Critical temperatures and pressures have been determined experimentally for the four lowest n-alcohols, 2-propanol, 2-butanol, and 2-methyl-1-propanol, and are given in the penultimate line of Table 3. The last line of Table 3 lists the weighted mean critical pressures, with the corresponding critical temperatures obtained from he vapour pressure equation. Comparison with the corresponding data from standard reference books reveals deviations from the experimental data in some [2, 4] and incorrect critical pressure for ethanol in all five reference books quoted in Table 3. In addition, vapour pressure data were obtained for the same alcohols in the temperature range approaching the critical point. The measurements are reproduced by the simplified Clausius-Clapeyron equation with the constants and standard deviation given in Table 2.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130117
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  • 19
    Electronic Resource
    Electronic Resource
    Influence of geometric and thermophysical properties of reaction layer on sulphur dioxide oxidation in transient conditions (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 131-135 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The sulphur dioxide to sulphur trioxide oxidation process in a fixed bed catalytic reactor is simulated in the case of cyclic change in the direction of the reaction mixture feed. It is shown that, for transient condition, the amount of catalyst in the reactor may be substantially reduced by its partial substitution with inert material of suitable form, dimensions and thermophysical properties, at the end of the layer. This makes the direct regenerative heat transfer process in these zones controllable, producing the same conversion and overall height of the layer. The results are significant for sulphuric acid production from gases poor in sulphur dioxide.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130118
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  • 20
    Electronic Resource
    Electronic Resource
    Sodium compounds as catalysts for methanol dehydrogenation to water-free formaldehydePaper presented at the “DECHEMA-Fachausschuß-Sitzung Technische Reaktionen” February 27 to March 1, 1989. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 145-149 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Formaldehyde is produced industrially from methanol by partial oxidation of oxidative dehydrogenation. In these processes, water is formed as a by-product. Anhydrous formaldehyde is required for many syntheses and, therefore, its production is of potential interest. In the present study, catalysts based on alkali compounds were found to be active in the dehydrogenation of methanol if absence of oxygen. Sodium carbonate doped with indium shows a selective of up to 75% for methanol conversion not exceeding 60%.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130120
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  • 21
    Electronic Resource
    Electronic Resource
    Characterization of Cu and K containing Fe/Mn oxide catalysts for fischer-tropsch synthesisDedicated to Professor Dr. Hansjörg Sinn on the occasion of his 60th birthday (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 156-161 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Copper and potassium containing Fe/Mn oxide catalysts for Fischer-Tropsch synthesis were investigated by X-ray microprobe technique, scanning electron microscopy, low-temperature argon sorption and carbon monoxide and carbon dioxide chemisorption at -80°C. The specific surface areas of the catalysts depend on the preparation method, e.g. addition of K or Cu by coprecipitation leads to an increase while impregnation results in a decrease in surface area. The resulting samples are inhomogeneous, as shown by all method. Mn and especially K accumulated on the surface of the catalysts. Addition of Cu and K considerably altered the selectivity and activity of the Fe/Mn oxide catalyst. High potassium contents produced high olefin to paraffin ratios but these catalysts became rapidly deactivated. Copper and a very small addition of potassium led to a very low olefin to paraffin ratio but showed a high and constant activity.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130122
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  • 22
    Electronic Resource
    Electronic Resource
    Determination of flooding gas velocity and liquid hold-up at flooding in packed columns for gas/liquid systemsPresented in part at the “GVC-Jahrenstreffen der Verfahrens-Ingenieure”, Strasbourg (France), September 17 to 19, 1986. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 184-196 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new model of suspended bed of droplets for describing the vaour or gas the vapour or gas velocity at the flooding point in packed of columns for rectification and absorption under vacuum and normal pressure is presented metallic, ceramic and plastic packings with diameters of 8-90 mm as well on sheet metal and gauze packings, in a wide range of liquid and vapour loads. Approximately 650 literature measurements and own data were evaluated. The mean relative error in determining the gas velocity at flooding point is less than ±5%. On the basis of the double layer model, a new equation was derived for the hold-up at flooding point, which is needed for the calculation of the flooding gas velocity. An example of calculations for sample applications is also included.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130125
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  • 23
    Electronic Resource
    Electronic Resource
    Evaluation of standard thermodynamic parameters for the sorption of n-hexane and methanol in zeolites (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 298-303 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Adsorption isotherms for n-hexane and methanol in mordenite and ZSM5 in the temperature range from 323 K to 473 K were found to be of type 1. The adsorbate-adsorbent interaction (C1) and adsorbate-adsorbate interaction (C2) wee computed according to Bradley and Wilkins model, whereas the Rees and Williams model predicts the adsorption characteristics. Finally, the thermodynamic parameters such as ΔGo, ΔSo, ΔHo, K, K+ have been evaluated for the sorption of n-hexane in mordenite and ZSM5.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130140
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    Heavy metal recovery by extraction and permeation in incineration preocessesPaper presented by H.-J. Bart at the “Jahrestreffen der Verfahrens-In-genieure”, Berlin, September 27 to 29, 1989 (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 313-318 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Incineration processes are critical for the environment. SO2 and NOX removal with processes is nowadays commonplace. Up to now, heavy metal were recovered via precipitation. The alternative use of liquid ion exchange techniques offers an easy re-use of the heavy metals, which are obtained as concentrates. A separation process is described, starting from laboratory experiments and ending with pilot plant field tests. A cost comparison for extraction, permeation and precipitation gives the scope of the necessary expenses for such environmentally controlled processes.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130142
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  • 25
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    Adsorption and catalytic reactions of NO and NH3 on activated carbonPaper presented by E. Richter at the “Jahrestreffen der Verfahrens-In-genieure”, Berlin September 27 to 29, 1989 (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 332-340 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In industrial processes, the reduction of nitrogen oxides by ammonia on activated carbons is carried out at temperatures between 90 and 190 °C. Adsorption of NO and NH3 on the catalyst was investigated separately. Reactions models for NO-reduction by carbon and ammonia were derived from experiments carried out in an integral reactor. In each case, the formation of an adsorbed (NO2)-complex is an important step. The kinetics of both reactions was described by modified Langmuir-Hinshelwood equations.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130146
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  • 26
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    Contribution to solving the problem of dioxins generated during waste incinerationPaper presented by H. Vogg at the “Jahrestreffen der Verfahrens-In-genieure”, Berlin, Seotember 27 to 29, 1989. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 221-229 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The production of dioxins/furans during waste incineration, and particularly the development of measures for minimizing the amount of generated pollutants, continue to command a considerable scientific as well public interest. Experiments are reported which were performed at the TAMARA municipal solid waste pilot incineration, erected on the premises of the karlsruhe Nuclear Research Centre. These experiments show that the solid waste mass flow rate and moisture content influence the dioxin/furan formation, Good removal efficiencies of dioxins/furans have been In wet cleaning. Hydrogen peroxide added to the crude gas is an interesting “killer” reagent for dioxins/furans.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130130
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  • 27
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    Study on regeneration of diesel particulate filter using a laboratory reactor (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 251-258 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Regeneration of diesel particulate filters can be accomplished by complete combustion of a collected particulate. A reactor has been developed for study of the regeneration in the presence of catalysts, additives and ignition aids. This reactor allows an accurate measurement of soot ignition temperatures and a kinetic study of soot oxidation with an undisturbed soot layer and under a defined gas composition. Results of various investigations carried out with this reactor are presented.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130134
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  • 28
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    Transport effects in catalytic fluidized-bed reactorsPaper presented at the Third National Meeting of Chemists, Dhahran, Saudi Arabia, March 12-14, 1989. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 273-277 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The majority of the fluidized-bed reactor models are models are rooted in the tacit assumption that transport between the bubble, cloud, and emulsion phases occurs in series with chemical reaction. A more realistic model that anticipates simultaneous transport and reaction is presented in terms of a fluid-bed effectiveness factor which embraces the limits between chemical and mass transport control. Analysis of the predictive capacity of this model vis-a-vis the Kunii-Levenspiel model reveals signal differences in chemical conversion.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130137
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  • 29
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    Computation of plate columns for NOx absorption by a new stage-to-stage method (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 289-297 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new stage-to-stage method has been developed for the calculation of NXx absorption columns. Each stage of the absorption column is simulated as a combination of a bubble column reactor (absorption) and an adiabatic plug for reactor (oxidation). The bubble column reactor is modelled as two single stirred tank reactors, one as a gas-phase and one as a liquid-phase reactor, both coupled by mass and heat transfer. In this hydrodynamic model, a dynamic approach is adopted, in which the gas-phase transport of N2O4 is the limiting step for the absorption. A gas-phasepseudo-enhancement for factor for N2O4 is therefore introduced. The balance equations for a single phase of the bubble column are solved with a Newton-Raphson algorithm. The entire column calculation is divided into a gas and a liquid side. On both sides, the stage-to-stage method is applied in such way that the overall calculation is performed as a loop process. The direction of the loop calculation follows that of the flow: gas-side upwards and liquid-side downwards.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130139
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  • 30
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    Formation of Di-isobutene, main by-product of methyl tertiary butyl ethyl ether synthesis catalyzed by ion exchange resin (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 150-156 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An experimental set-up is presented for the measurement of steady-state reaction rates in the liquid phase methyl tertiary butyl ether (MTBE) synthesis from isobutene and methanol using ion exchange resin as catalyst. This apparatus was used for a separate investigation of the main side reaction, i.e., the formation of isobutene dimers (DIB), in the temperature range between 60 and 90°C. The reaction catalyzed by Amberlyst 15 (A15) showed no steady-state behaviour, but the catalytic activity declined at a rate dependent on the reaction conditions. Time constants for activity loss were determined in the range from 3.5 to 30 h. The deactivated A15 catalyst could be regenerated through MTBE synthesis experiment. Deactivation is assumed to be caused by blocking of the microparticle gel phase by higher isobutene oligomers. The DIB formation, using 1-butene as solvent, was of 2nd order with respect to isobutene and showed an apparent activation energy of about 40 kJ/mol.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130121
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  • 31
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    Evaluation of plug flow assumption in packed beds (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 161-171 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Knowledge of modelling and computer simulation is an essential prerequisite for type design and operation of packed bed systems. Unfortunately, the existing models are based on a number of weak assumptions of which plug flow can be considered as a common deficiency. Such a simplification would inevitably have a noticeable bearing on the accuracy of the final design and consequently calls for the development of a coherent mathematical description of the packed bed systems so that reliable design information can be explored. A two-dimensional heterogeneous transient model has been developed which allows for the radial variations of velocity and void age. The model equations have been solved using numerical approximation. The simulated results reveal significant differences between the present refined data and those established from existing plug flow models.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130123
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  • 32
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    Batch cooling crystallization at constant supersaturation: Technique and experimental results (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 229-237 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new laboratory plant for batch cooling crystallization is described, which allows to maintain the supersaturation at a constant level during an experimental run. A method for continuous supersaturation measurements has been developed, using a density meter and a hydrocyclone. Experimental results obtained from a seeded solution in constant supersaturation cooling mode and at constant cooling rate are compared. In the case of a constant cooling rate, the supersaturation passes through a sharp maximum, whereby effective nucleation is enhanced. As a consequence, a smaller median crystal size is obtained than for cooling at constant supersaturation. Equation for controlled cooling at a constant supersaturation require an accurate description of the effective rate of nucleation. Therefore, the mechanical stress, to which the crystals are subjected, must be included as the main source of new nuclei. This is shown by the influence of stirrer on batch time.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130131
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  • 33
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    Thermal decomposition of 2, 3-dimethyl butane: Experiments and mechanistic modelling (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 241-251 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pyrolysis of 2,3-dimethyl butane (DMB) was carried out in a quartz flow reactor in the temperature range from 740 to 1032 K at normal pressure. The input concentration of DMB was 3.3 × 10-3 mol/1 using argon as diluent. Reaction time ranged between 3.1 and 3.9 s. The following products were analyzed by two-column gas chromatography: hydrogen, methane, ethene, propane, propene, butenes, butadiene, 2-methyl-2-butene, isoprene, benzene and toluene. Compared to thermal decomposition of n-hexane under similar experimental conditions, the main difference concerned the formation of ethylene, ethane and branched alkanes. A reaction model, based on elementary reactions, was developed to predict the experimental results and to verify our data basis of elementary reactions under different conditions. The model gives a quantitative description of the complex chemistry of the process. In addition, an algorithm is presented for model reduction.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130133
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    New and overlooked relationships for turbulent flow in channelsPaper base on a poster at the “Jahrestreffen der Verfahrens-In-genieure”, Berlin, September 27 to 29, 1989. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 264-272 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper describes general, asymptotic and speculative relationships which can be deduced directly from the time-averaged form of the basic, partial-differential model for the conservation of mass and momentum in fully developed turbulent flow of constant-property fluids through round and parallel-plate channels. Such relationship are shown to provide insight as well as useful forms for correlation. Several analogies for flow in round tubes and between parallel plates which have generally been overlooked are reexamined and extended. A generally overlooked anomaly which occurs for flow in concentric, circular annuli, for flow between plates of non-identical roughness, and for the combination of forced and wall-Ind.uced flow between parallel plates is also is noted. The data needed to test the above analogies and to quantify the deviations, if any identified, as well as those needed to generalize the anomalous behavior.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130136
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  • 35
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    Motionless mixers for the design of multitubular polymerization reactors (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 214-220 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental investigations of thermal bulk polymerization of styrene in pilot plants of different sizes have been performed. Each pilot plant is composed of a tubular recycle reactor, connected in series with a tubular reactor, both completely filled with Sulzer motionless mixers. Kinetic, reactor and viscosity models have been verified in a wide range of styrene conversions (up to 96%) temperatures (up to 210 °C) and polystyrene molar masses (up to 360 000). Scale-up studies were carried out which confirmed that multitubular reactors of special design can be applied for industrial polymerization process.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130129
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  • 36
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    Large-scale anaerobic/aerobic treatment of complex industrial wastewater using immobilized biomass in fluidized bed and air-lift suspension reactorsPaper presented by J. J. Heijnen at the GVC-VDI Congress “Verfahrenstechnik Abwasserreinigung”, Baden-Baden. October 17 to 19, 1988. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 202-208 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Warm concentrated industrial wastewaters are preferably treated in an anaerobic reactor for reasons of energy generation and low surplus sludge production. Problems to be solved in the practical application concern a low growth rate of the micro-organisms, their low settling rate, process instability and the need for after treatment of the noxious anaerobic effluent which often contains NH4+ and HS-. The use of biomass immobilized on small suspended carriers (〈 0.5 mm) has proven to be a suitable means to overcome most of these problems. Results are presented on pilot and full-scale pretreatment of industrial wastewater in an anaerobic 2-state fluidized bed reactor for CH4-production and laboratory and pilot scale post-treatment of the anaerobic effluent, which contains NH4+ and HS- in an aerobic air-lift suspension reactor for the production of NO3- and SO42-.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130127
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  • 37
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    Anodic dehalogenation of 1,2-dichloroethane in aqueous electrolytesDedicated to Professor Dr. Karl-Hans Simmrock on the occasion of his 60th birthday (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 371-375 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A solution of 0.1 M 1,2-dichloroethane in 1 M H2SO4 was anodically converted to CO2, Cl2 and HCIO4 as the main products at smooth platinum. The current efficiency for CO2 exceeds 60% at low current densities, while HClO4 is obtained with about 20% current efficiency. Chlorinated products such as 1,2′,2-trichloroethane are formed in negligible amounts. Platinum plays a distinctive role as anode material and shows a reaction limited anodic prewave. Our experimental findings lead to a mechanism, whereby DCE is initially hydroxylated to form chloroacetaldehyde chlorohydrin which releases HCl and becomes rapidly further oxidized to monochloroacetic acid. The cleavage of the C—C bond proceeds via its anodic decarboxylation. Possible practical applications in the field of anodic water purification and in the direct electrosynthesis of vinyl chloride are discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130150
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  • 38
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    Search for optimal geometry of a conical turbine agitator for heat transfer in stirred vessels (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 384-392 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Simultaneous measurements of power consumption P and heat transfer coefficient α for a jacketed, baffled, agitated vessel of diameter D = 0.45 m, equipped with a conical turbine, were carried out. The following geometric parameters of the agitator were tested: diameter d, blade width b and number Z, and distance from the bottom of the vessel to the lower edge of the blade h. The results of these investigations were generalized mathematically. On the basis of optimization, the best geometric parameters with respect to heat transfer are proposed for the conical turbine agitator.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130152
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  • 39
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    Collection of fine adhesive and cohesive dusts with pluse-jet fabric filersPaper presented by E. Schmidt at the “Jahrestreffen der Verfahrens-Ingenieure”, Berlin, September 27 to 29, 1989. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 402-410 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The collection of reactive and therefore extremely adhesive and cohesive fine particles (〈 1 μm) by means of bag filters with pulse-jet cleaning may present problems. The electron-beam dry scrubbing (EBDS) process, used to remove SO2 and Nox in a power plant of the Badenwerk AG, Karlsruhe, serves as an example. To solve the occurring problems and achieve a satisfactory filter performance, extensive know-how of process engineering is necessary. This contribution deal with the following aspects: construction of the cleaning system, selection of filter medium, precoating, and dosage of an auxiliary dust during filtration.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130155
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  • 40
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    The Markov process approach to modelling of residence of time distributions in flow systems (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 422-425 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Markov process approach, as used in the modelling of particle residence time distribution in a flow system of interlinked compartments, has been compared with the deterministic model of a complex reaction system of the first order. In the latter model, interfacial reactions take place between flowing phases, corresponding to the compartments in the stochastic model. It has been demonstrated that the two approaches are equivalent. A direct method of calculating the higher moments of the residence time distribution has been verified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130157
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  • 41
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    Effect of dispersions of CSD in continuous MSMPR crystallizers (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 426-431 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A general model is proposed to predict the crystal size distribution from multistage MSMPR Crystallizers taking into account shape factor, birth size and growth rate dispersions. Two cases, namely nucleation in the first crystallizer and the same process in all crystallizers have been considered. The developed equations can be solved easily by the Monte Carlo technique. The model represents an extension of the earlier work of Sen Gupta and Dutta.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130158
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  • 42
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    The implications of carboxylic acid propertiesDedicated to Professor, Dr. rer. nat. Wolfgang Hilger on the occasion of his 60th birthday (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 304-312 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Some properties of carboxylic acids are reviewed, with emphasis on recent experimental data, Qualified, consistent latent heat of vaporization data were developed for the series and a two-population viewpoint is suggested. The equation of state formulated by Grenzheuser [1] is also recommended as a practical tool, and its further development is urged.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130141
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  • 43
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    The linear relationship between stoichiometry and dimensional analysis (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 328-332 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The linear algebraic character of the formal representation of chemical species and their reactions is compared with the procedure of searching for dimensionless numbers in a set of physical quantities. A straightforward algorithm is presented to find a finite set of solutions to the relevant system of “balance equations”, the so-called minimal (or simple) solutions. At the third stage of the hierarchy thus established, “mechanisms” among reactions as well as “representations” among dimensionless group can also be defined.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130145
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  • 44
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    A fluid-dynamically based model of bubble column reactorsPaper presented by H.-E. Gasche at the “Jahrestreffen der Verfahrens-Ingenieure”, Berlin, September 27 to 29, 1989. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 341-349 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A heterogeneous fluid dynamic model has been developed to describe the complex flow structure of two-phase in bubble columns. The equation of continuity and momentum balances form the basis of the model. Coupling of the two phases occurs via an interaction force, deduced by a force balance around a single rising bubble. Multiphase flow mixing processes are taken into consideration by introducing turbulent viscosities of the two phases involved. The Simulation program was extended to reactive system, taking into account the mass balances of a second order gas-liquid chemical reaction as well as the different absorption/reaction regimes. The gas phase concentration profiles show pronounced axial and radial dependences, while the liquid phase can be regarded as a CSTR with respect to the liquid component. With reference to the gaseous component, which is being absorbed in the liquid phase, the degree of back mixing does not show CSTR behaviour as the influence of different absorption conditions in different axial and radial reactor positions is superposed on that of turbulent motion of the liquid carrier of the dissolved gaseous component.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130147
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  • 45
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    A reaction model for the electrochemical synthesis of adipontrile (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 376-383 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A theoretical and experimental study of the electrohydrodimerization process to produce adiponitrile is used to determine an appropriate reaction model. From numerical simulations of five proposed reaction schemes and subsequent comparison with experimental data, the most favoured route is via an anion, intermediate of acrylonitrile. This route, a five step reaction involving electrochemical and chemical reaction in a diffusion/reaction layer, gives good predictions of product distributions over a wide range of current densities and acrylonitrile concentrations of product distributions over a wide range of current densities and acrylonitrile concentrations.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130151
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    Some strategies for the kinetic study of complex heterogeneous catalytic reactions (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 397-402 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper presents a method of transforming the non-liner regression problem in the kinetic study of complex heterogeneous catalytic reactions into a linear regression problem. Application of this method reduced the number of parameters to be estimated by n-1, where n is the number of independent reactions. In addition, a stepwise model discrimination strategy in introduced to reduce the number of equation sets ad equations in the set undergoing parameter estimation. These two new approaches are very advantageous in reducing the computation effort, especially when the number of independent reactions is large. The linear regression method and the stepwise model discrimination strategy are successfully applied in the kinetic study of the methanol synthesis system in which the formation rates of methanol, methane, ethanol and ethane are considered.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130154
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    Measurement of transient deformations by double-pulsed holographyPaper presented by M. Hajduk at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 1-8 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Holographic interferometry is used for the determination of surface deformation of items of equipment. The material failure which caused the surface deformation can then be identified. Because a double-pulsed laser is used to plot the hologram, non-vibration stabilized holographic equipment is necessary. Thus, non-destructive testing of equipment components is also possible during plant operation. In this report, we present the experimental results of non-destructive testing of composite materials. We examined centrifugally cast pipes and filament wound pipes, which were made from glass fibre reinforced plastic and carbon fibre reinforced graphite. As a rule, the severity of failure is characterized by the apparent perturbation of its holographically stored fringe pattern. In this report, we present the experimental results which yield the relationship between the perturbation of interference fringes and the extent of the specific types of failure. Measurement results were compared with displacements calculated by the finite element method. By using the interferogram, and with the knowledge of tension stress beneath the surface, the size of the crack can be estimated. The size of the smallest detectable flaw was clearly smaller than the critical flaw size. Thus, holographic interferometry is suitable for detecting damage to cylindrical containers.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130102
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    Breakthrough behaviour of a binary gas mixture with azeotropic adsorption equilibriumPaper presented by C. Persichini at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 8-14 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This contribution reports on the breakthrough behaviour of binary gas mixtures with ideal and non-ideal multicomponent adsorption equilibria. Investigations were carried out on mixtures CO2/C2H4 and C2H4/C2H6, both adsorbed on molecular sieve 5A (ms5A). The adsorption equilibrium of the system CO2/C2H4/ms5A may exhibit azeotropic behaviour, which subsides with decreasing active pressure (= sum of partial pressures of adsorbable components) or on raising the temperature. In contrast, the system C2H4/C2H6/ms5A maintains its ideal behaviour also at higher active pressures or lower temperatures. Attempts to calculate the non-ideal adsorption equilibrium from measured single component isotherms have failed when known models were applied. The investigation of the effect of azeotropic equilibrium on the fixed bed adsorption led to intersecting breakthrough curves of the two components. This behaviour is due to a displacement of equilibrium caused by the change in the active pressure and partial pressures, and a superposed temperature effect. This can be shown by calculating the breakthrough curves with the equilibrium model.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130103
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    Modelling of a fluidized bed bioreactor for immobilized enzymes (Part 1)Paper presented by T. Kiesser at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 20-26 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the first part of this paper, a mathematical model is presented for a liquid fluidized bed bioreactor using immobilized enzymes with reversible Michaelis-Menten kinetics. The model is based on the axial dispersion model for the bulk liquid phase. Inter- and intraparticle mass transfer as well as enzyme catalyzed reaction inside the porous beads are considered. The overall efficiency of the biocatalysts is calculated by a numerical routine. For the calculation of the concentration profile inside the reactor, a semi-analytical solution is derived which takes into account the height dependence of the effectiveness factor.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130105
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    Influence of feed solids concentration on the performance of hydrocyclonesPaper presented by Th. Braun at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 15-20 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Even though the influence of solids concentration in the feed on the separation efficiency of hydrocyclones has long been recognized, a systematic research on the change in pressure drop across the hydrocyclone and the latter's separation characteristics has thus far been lacking. If all other operating parameters are kept constant, an increase in feed concentration generally leads to a coarser cut size, reduced sharpness of separation and a rise in pressure drop. Apart from the particles hindering one another's radial motion, the limited capacity of the apex valve and the changes in the flow field within the hydrocyclone cause additional particles to be entrained by the overflow. The flow ratio thus becomes an additional parameter in determining the cyclone efficiency. A theoretical model, which takes these effects into account, has been developed and successfully tested against experimental data.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130104
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    Effect of nuclei storage and growth rate dispersion on the transient behaviour of continuous crystallizers (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 63-71 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bench scale experiments and computer simulations of transient crystal size distributions obtained in a 1.4 m3 sucrose crystallizer, which prove the existence of nuclei stock, are presented. This stock represents a large number of non-growing nuclei, which can be activated at increased supersaturations. The nuclei stock attenuates the dynamic behaviour of crystallization process.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130109
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    On supersaturation during mass crystallization from solutionPaper presented by M. Kind at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 50-62 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Supersaturation is the driving force for crystallization from solution. For design and operation of crystallization processes, it is necessary to apply a set of criteria for the determination of appropriate or even optimum supersaturation. In this paper we present and discuss the results of our experimental and theoretical investigations on supersaturation during crystallization from solution. While the determination of the metastable zone width of the solution is frequently applied as a fast check on solution behaviour, we demonstrate that the determination of the induction period of the supersaturated solution is a useful aid in ascertaining the maximum allowable supersaturation. Theoretical considerations and experiments confirm that the induction period dependssoley on growth kinetics if secondary nucleation is the predominant mechanism. In order to avoid uncontrollable spontaneous value of between 70 and 130 μm during crystallization. Since growth kinetics turns out to be the only important system property for the determination of maximum possible supersaturation, we conclude the paper with some arguments concerning a closed representation of growth kinetics.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/ceat.270130108
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    Biological treatment of effluents from a coal tar refinery using immobilized biomassPaper presented by P. Hüppe at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 73-79 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An airlift-loop reactor with a fluidized bed was used for the microbiological removal of a complex mixture of aromatic substances originating from coal tar process waters. A specially adapted mixed microbial culture derived from several soil and sludge samples was immobilized on fluidized sand particles and retained in a reactor at high biomas concentrations of 3 to 16 g dry matter per liter, depending on the COD-load. In a two-stage pilot plant, those aromatic substances which passed through the first stage either unaltered or only partially oxidized were effectively eliminated by the immobilized biomass in the second stage. Whereas most of the waste water components such as phenols and quinoline were already degraded by a conventional activated sludge system in the first stage, the majority of nitrogen-containing aromatic bases could be sufficiently eliminated with specially adapted micro-organisms in the second stage. Although the COD-feed load was increased to 12 and 15 kg m-3 d-1 in the first and second stages, respectively, it was removed to the extent of 87% on the average with an overall residence time varying between 11.5 and 29 h.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130110
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    Foam breaking by high speed rotors (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 86-96 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The first part of this paper presents a relationship for the minimum velocity of rotating installations for foam breaking. The derivation is based on equilibrium of inertia and surface forces. Inertia forces occur during the acceleration of foam bubbles and act mainly at the plateau borders. High and definite acceleration can be obtained with a deformer composed of a rotor and a stator. The surface force is due to the dynamic surface tension because surface-active solutions react to a rapid change in surface area by altering their surface tension. The theoretical relationship is compared with experimental results of minimum velocities needed to break foams produced from aqueous solutions of detergents. The equation presented here explains why measured minimum velocities often range between 10 and 20 m/s. The second part of the paper deals with condensation of continuously generated foam in a closed system. In the process of condensation, foam is not completely separated into liquid and gas phase but turns into foam with small bubbles and high density. The collapse of this condensed foam must be considered for the control of persistent foams in a closed system. The collapse of foams made of aqueous solutions of different surface-active agents has been investigated. Different highly surface-active agents show small variations in times of coalescence. A relationship for the lifetime is given, which is based on laminar flow along plateau borders. Recommendations are made with respect to the geometry of the foam breaker, scale-up and operating variables such as rotational speed of the foam breaker and gas flow rate.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130112
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    Modelling of a fluidized bed bioreactor for immobilized enzymes (Part 2)Paper presented by T. Kiesser at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 80-85 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the first part of this contribution, a mathematical model was presented for a liquid fluidized bed using immobilized enzymes, with reversible Michaelis-Menten kinetics. This part is focused on the experimental results. The reaction kinetics of native and immobilized enzymes was determined in continuous stirred tank reactors under comparable conditions. The influence of external mass transfer was investigated in a fixed bed reactor column. The extend of pore diffusional resistance was examined in a continuous stirred tank reactor and with a numerical simulation. Hydrodynamics was measured in different reactor columns (diameter dt = 0.052 - 0.225 m; length L: 1.0-2.0m) and with a static mixer. Further, the concentration profile was determined in a fluidized bed reactor with side stream analysis for different biocatalyst samples, fluid velocities and bed heights. The simulation of experimental results indicates that they are well described by the developed model. Furthermore, the model is well suited to predicting the influence of specific parameters on the effective kinetics of the biocatalyst and the expansion of the fluidized bed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130111
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    Absorption of NO2/N2O4 in nitric acid (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 97-101 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Laboratory-scale measurements were performed on the absorption of NO2 gas into diluted nitric acid. The concentration of NO2 gas, which represents an NO2/N2O4 equilibrium, varied from 1000 to 20000 ppm, the carrier gas being nitrogen. The concentration of nitric acid ranged from 15 to 60 mass-%. The absorption experiments were carried out in a double stirred cell, with a defined gas/liquid interface as the mass transfer area. The liquid phase was conducted periodically and the gas phase continuously. Mass flow rates were determined. The well-known film model of absorption was used for analyzing the experimental results. Only the N2O4 species was considered to pass the gas/liquid interface. The measured data yielded values of HN2O4(k D1)1/2 as well as their variation with temperature and nitric acid concentration.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130113
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    Modelling of thermal desorption of active coke loaded with sulphuric acid and ammonium sulphatePaper presented at the “Jahrestreffen der Verfahrens-Ingenieure”, Hannover, September 21 to 23, 1988. (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 101-112 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The BF-Uhde-Mitsui Process uses active coke for SO2- and NOx-removal from flue gases in the temperature range between 100 and 190 °C, Experimental methods of thermal regeneration were applied to the evaluation of the state of the adsorbent after use in flue gas cleaning and of the parameters for disrober design. A reaction model was derived from experiments carried out in differential and back-mix reactors. The parameters were evaluated by adaptation of the model to the adsorption spectra. The model was successfully applied to the regeneration of active coke in a fluidized bed reactor.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130114
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    Influence of gas flow on heat transfer in film condensation (1990)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 13 (1990), S. 136-143 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For the dimensioning of condensers in film condensation, the heat transfer coefficient between film surface and cooled tube wall must be known. Generally, Nusselt equations are used which have been verified by experiments. When there is no significant gas flow, a large number of equations correlate the experimental. data very well. The description of heat transfer enhancement by a significant gas flow is not sufficiently covered by the available literature. For film wise condensation in a vertical tube, a calculation method is presented which reproduces this phenomenon characterized by the interfacial shear stress at the film surface. This method is based on the assumption that, in the proximity of gas flow, the condensation process also affects the interfacial shear stress. A comparison with known experimental local Nusselt numbers showed a good agreement with water as the fluid. For test fluid MWA, which was used by Blangetti, the measured values show only a moderate agreement with theoretical calculations. Possibly, this is related to entertainment which occurred during measurements at film Reynolds numbers of over 80.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270130119
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    Rate-equilibrium LFER characterization of transition states: The interpretation of α (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 1-8 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of substituents on the rate of a reaction and the effect of the same substituents on the equilibrium can often be related by a linear free energy relation (LFER): log k- = α log K= + constant, where k+ and K= are the rate constant and the equilibrium constant, respectively. This review, concentrating on group transfers, adds to many studies describing the use of α to describe the transition state. Although the use of α to describe transition states is general, group transfers constitute a simple class allowing a fairly complete description yet illustrating two often neglected contributions. Group transfers can be described by the Marcus equation relating rate to an average identity rate and the equilibrium constant; a major contributor to the slope, α, of the rate-equilibrium LFER is the variation of identity rates with substituent, rather than reflecting product-like character. Substituent effect LFERs are predominantly attributable to interaction of charges with the substituent. However, α is not an exact measure of the charge on the substituent-containing group, because in a transition state, but often not in a reaction product, there are more remote centers of charge which exert a smaller attenuated effect. A simple treatment of this attenuation for group transfers is proposed. The possibility of application of these ideas to proton transfer reactions and the interpretation of the Brønsted α (or β) is proposed.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030102
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    Maximally inhibited elimination of kinetics of (2-bromoethyl)benzene and 1-bromo-3-phenylpropane in the gas phase. Anchimeric assistance of the phenyl group (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 77-80 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The gas-phase elimination kinetics of (2-bromoethyl)benzene and 1-bromo-3-phenylpropane were studied in a static system and seasoned vessels over the temperature range 390-450 °C and the pressure range 32-104 Torr. The reactions, under maximum inhibition of 4-fold pressure of the free-radical suppressor cyclohexene and/or propene, are homogeneous, unimolecular and obey a first-order rate law. The rate coefficients are given by the following Arrhenius equations: for (2-bromoethyl)benzene, log k1 (s-1) = (13·04 ± 0·10) - (210·8 ± 1·3) kJ mol-1 (2·303RT)-1, and for 1-bromo-3-phenylpropane, log k1 (s-1) = (14·09 ± 0·27) - (227·7 ± 3·6) kJ mol-1 (2·303RT)-1. The phenyl group of (2-bromoethyl)benzene appears to provide anchimeric assistance in the HBr elimination of this compound. However, neighbouring C6H5 participation at the 3-position in 1-bromo-3-phenylpropane for a C-4 conformation is apparently absent. The mechanisms of these reactions are discussed.
    Additional Material: 8 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610030203
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    Hydration of 2,2-dichloro-1-arylethanones in water and tetrahydrofuran-water mixtures (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 89-94 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The hydration of 2,2-dichloro-1-arylethanones was studied in water and tetrahydrofuran (THF)-water mixtures and the equilibrium constants in water were estimated for four ethanones. The process is subject to specific acid and to general base catalysis. The proton inventory technique was applied to the study of the reaction in L2O and THF-L2O solutions (L = H or D). In pure water and water-rich mixtures, a very large number of protons participate in the open transition state, this number decreasing gradually with increasing water content in the mixture, until the minimum value of 2 is reached, corresponding to a cyclic, closed transition-state structure.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030205
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    Additivity of bond separation energies of hydrocarbons and their thermochemical data (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 126-134 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The additivity of experimental bond separation energies is demonstrated. This thermodynamic function can be reproduced by summation of group equivalents with a correction for the ‘stabilization’ energy. For this purpose, several group equivalents have been developed for alkanes and alkenes. The correlation between the computed and the experimental bond separation energies is good. These equivalents are then used in evaluating the stabilization (destabilization) energies for aromatic hydrocarbons and polyenes. The results obtained are in good agreement with values reported in the literature.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030209
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    Kinetic and spectroscopy of 2-naphthylphenylcarbene (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 135-138 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 2-Naphthylphenylcarbene (2-NPC) was studied by low-temperature EPR spectroscopy and by solution-phase laser flash photolysis. 2-NPC was found to have a triplet ground state with two distinct rotomeric forms. The triplet carbene was found to react with methanol, 1,1-diphenylethylene, styrene, carbon tetrachloride, isoprene, toluene and 2-methyltetrhydrofuran.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610030210
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    Stereochemical studies. XXXIVPart XXXIII, I. G. Mursakulov, V. A. Svyatkin, V. V. Samoshin, N. S. Zefirov, Zh. Org. Khim. 22, 773-776 (1986).. Quantitative description of ring puckering via torsional angles. The case of six-membered rings (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 147-158 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The quantitative description of ring puckering suggested by the authors is compared with that of Cremer and Pople. The applicability of both methods is discussed for the case of six-membered rings with the use of model calculations simulating various ring distortions and with the analysis and comparison of puckering parameters computed on the basis of x-ray data for 40 six-membered rings in different cyclic structures. The 2N times reduction of the field of variation of puckering parameters for the N-membered ring is suggested and the algorithm for the renumbering of the ring atoms for this purpose is described for six-membered rings.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030304
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    Deuterium fractionation factors for carbon-hydrogen bonds: Calculations using scaled quantum-mechanical force constants (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 181-189 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The determination of uniform scaling factors for force constants calculated at the STO-3G and 4-31G levels of ab initio SCF MO theory is described; scaled 4-31G force constants provide reasonable estimates of reduced partition function ratios for deuteriated/protiated molecules. Gas-phase deuterium fractionation factors relative to methane calculated using scaled 4-31G force constants are, however, consistently too high, whereas those obtained by the MP2/6-31G* and scaled STO-3G methods are inconsistent. Scaled 4-31G deuterium fractionation factors relative to water for a range of structural moieties correlate linearly with experimental aqueous-phase values, but are also consistently overestimated. Substitution at a hydrogen-bearing carbon atom affects the deuterium fractionation factor through the combined effect of changes in reduced mass and changes in force constants other than for CH stretching.
    Additional Material: 8 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610030307
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    The decay of 2-phenyl-1,3-dioxolane-2-ylium salts in solution (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 195-199 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The decay of 2-phenyl-1,3-dioxolane-2-ylium salts in 1,2-dichloroethane solution has been studied by means of 1H NMR and UV spectroscopy and conductimetry. The influence of the nature of the anion (SbCl6-, SbCl5Br-, AsF6-) and of the methyl substituents on the rate constants of decay is discussed.
    Additional Material: 3 Ill.
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    Masthead (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030401
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  • 68
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    Photochemical electrocyclization of the allyl radical into the cyclopropyl radical (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 219-229 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Following the observation that allyl radicals trapped in an argon matrix can be photolytically converted into cyclopropyl radicals (λ = 410 nm, 18 K), the IR spectrum of the cyclopropyl radical was recorded for the first time and interpreted. Bicyclopropane and cyclopropane are formed when the photolysed argon matrix is warmed from 18 to 35 K. The identification of these new species unequivocally proves the presence of cyclopropyl radicals in the photolysed matrix. This radical is shown to be a σ-type (Cs symmetry) and not a π-type (C2v symmetry) radical; of the 18 normal frequencies of the Cs cyclopropyl radical, all active in the IR, 16 were observed and were assigned to their corresponding normal modes. For this assignment advantage was taken of ab initio frequency computations reported in the literature and performed by the authors.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030403
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  • 69
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    Organophosphorus herbicides and plant growth regulators part 1. Synthesis and protonation behaviour of glyphosate and related compounds (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 248-254 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ionization constants of N-phosphonomethylglycine (glyphosate) and three structurally related plant-growth regulators were determined by potentiometric titration. The effect of pD on the chemical shifts of the 1H and 13C nuclei of the methylene groups and of the 31P nucleus in these substrates was measured by NMR spectroscopy. The results allowed an assignment to be made of a specific site (carboxylic, phosphonic, ammonium) in the molecule to each of the determined pKa values.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030407
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  • 70
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    Concentration-dependent deuterium isotope effects on the quantum yield of arene-alkene meta photocycloaddition: The role of excimers (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 273-278 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A deuterium isotope effect on the arene-alkene meta photocycloaddition, reported earlier for toluene/toluene-d8 photoaddition to cyclopentene, was found to depend on the concentration of both arene and alkene. This phenomenon is explained in terms of an unbalanced dissociation of ‘mixed’ excimers, which play a role in the intermolecular competition experiments.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030411
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  • 71
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    Mechanism of α-substitution reactions of acrylic derivatives (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 285-288 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reactions between acrylic esters, nitriles and similar compounds on the one hand and aldehydes and ketones on the other, catalysed by tertiary amines, lead to α-(hydroxyalkyl)acrylic compounds. Evidence on the basis of kinetics, volumes of activation and of reaction, and kinetic isotope effects is presented to deduce a mechanism in which amine first undergoes Michael addition, the resulting enolate ion adds to the carbonyl compound in a rate-determining step and finally base is eliminated. An analysis of the solvent effect on rates is also presented.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030503
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  • 72
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    [4]Paracyclophane: MNDO and STO-3G molecular structure and strain energyTaken in part from Ref. 1. (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 295-300 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The molecular structure of [4]paracyclophane was optimized at the semiempirical MNDO and the ab initio STO-3G level. A comparison of the results showed that the benzene ring is much less bent at the STO-3G level. Although some bond alternation is predicted at both levels of theory, the aromatic carbon-carbon bond lengths are still in the range typical of highly delocalized compounds. The calculated strain energy [SE(tot.)] of [4]paracyclophane is larger for the STO-3G structure. Nevertheless, the distributions of SE(tot.) over the bent benzene ring [SE(bb.)] and the oligomethylene bridge [SE(br.)] are the same for the MNDO and STO-3G structures.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030505
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  • 73
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    Configurations and dipole moments of O-substituted hydroximoyl cyanides. Stereoelectronic effects in the ground state of oximino compounds (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 316-324 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dipole moments of the Z and E isomers of O-methylbenzohydroximoyl cyanides [ArC(CN)=NOCH3, Ar = C6H5 and 4-NO2C6H4], the Z isomers of benzohydroximoyl cyanides [ArC(CN)=NOH, AR = C6H5 and 4-NO2C6H4] and the Z isomers of O-benzoylbenzohydroximoyl cyanides [ArC(CN) = NOCOC6H5, Ar = C6H5 and 4-NO2C6H4] were measured. An analysis of these dipole moments indicates that anti delocalization from the OCH3 (OH) group has a small but significant effect on the overall direction and magnitude of the dipole moment. Semi-empirical molecular orbital calculations at the MNDO level support this proposal. The x-ray crystal structure of (Z)-O-methyl-p-nitrobenzohydroximoyl cyanide was carried out to confirm the configuration of the compound.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030508
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    Masthead (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030601
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  • 75
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    Stereochemistry and kinetics of thiophenoxide ion addition to methyl para-substituted phenylpropiolate derivatives in methanol. I (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 375-378 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reactions of a series of methyl para-substituted phenylpropiolates with thiophenoxide ion in methanol were studied and their rates measured. Methyl β-thiophenyl esters were obtained as mixtures of Z and E isomers and their configurations were established by 1H NMR spectroscopy. Good Hammett correlations with ρ values of 1·57-1·97 were obtained, which suggest a carbanionic character of the transition state. A stepwise mechanism proceeding via an intermediate carbanion is postulated for this non-sterospecific addition reaction.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030605
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  • 76
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    Structural studies of halogen adducts of diorganyl chalcogenides in solutions by 1H, 13C, 77Se and 125Te NMRFor a preliminary contribution, see Ref. 1. (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 358-368 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 1H, 13C, 77Se and 125Te NMR spectra were measured for several sulphides, selenides, tellurides and their halogen adducts to establish the criteria for distinguishing trigonal bipyramidal (TB) adducts from molecular complexes (MCs). TB formation caused large downfield shifts for methyl protons and methyl, ipso and para carbons of methyl and phenyl selenides and tellurides. Large downfield shifts (〉 100 ppm) were also observed for selenium and tellurium by the formation of TB from the parent selenides or tellurides. The plots of the 125Te vs 77Se chemical shifts for a set of corresponding compounds gave a straight line with a slope of 1·74, showing that the linear relationship holds well for tellurides and selenides and their TB adducts examined in this work. Upfield shifts of the ipso carbons were characteristic of MC formation. The para carbon signals of MC appeared downfield relative to those of the parent selenides, although the shift values were not so large. The 77Se signals for MC shifted slightly downfield (≤ 10 ppm). The dissociation constants for iodine adducts of dimethyl selenide and selenoanisole were determined. The MC structure of bromine adducts of sulphides is well demonstrated on the basis of the criteria set out. 1H and 13C NMR spectra of ethylbenzene and ethers were also recorded in the presence of iodine or bromine. However, their chemical shifts were the same as those in the absence of iodine or bromine, within experimental errors.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030603
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    Reaction of aryliminodimagnesium with diphenyl diketones: Heat evolution accompanying single electron transfer and chelate formation, and product distributionAryliminodimagnesium Reagents Part XVII. For Part XVI, see Ref. 1. (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 379-389 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reaction of diphenyl diketones (benzils) with aryliminodimagnesium [ArN(MgBr)2, IDMg], a magnesium reagent having condensation ability, was investigated. By comparison of the relative amounts of heat evolved in the reactions of IDMg (mildly electron donating) and ArMgBr (strongly electron donating) with some carbonyl and nitro compounds, results were obtained supporting the reported correlation of the relative yields of normal and abnormal (radical) products with single electron transfer (SET) efficiency estimated by the oxidation and reduction potentials of reactants. A sole exceptional result, i.e. the great heat evolution caused by the combination of benzil and IDMg, was attributed to the generation of tightly chelated radicals via SET. The involvement of stepwise SET was confirmed by ESR. On the basis of these results, substituent effects of benzil and mono-condensation products on their reduction potentials and on the relative yields of normal (mono- and di-condensation) and abnormal (dimerization) products were examined. All the results were consistently explained in terms of the relative efficiency of chelation (or σ-complexation) and SET in two main processes. The role of the initial stages involved in the processes governing the final product distribution is discussed.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030606
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    Correlations of rate and selectivity of a Diels-Alder reaction with Sp parameters (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 414-418 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The rate and endo/exo selectivity of the Diels-Alder reaction between cyclopentadiene and methyl (E)-α-cyanocinnamate at 25°C, in several acetone-water and 1,4-dioxane-water mixtures, were measured. The linear correlations of log k and log(endo/exo) vs solvophobicity are reported. Correlations for selectivity are considerably improved when the results obtained in acetone-water and 1,4-dioxane-water are taken as separate series.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030610
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    Substituent effects in the solvolysis of benzyl tosylates (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 449-455 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The substituent effect on the rates of solvolysis of substituted benzyl tosylates in acetic acid was analysed based on the Yukawa-Tsuno LArSR equation. Neither the LArSR nor simple σ+ treatment was capable of providing any linear correlation plot for the full range of substituents. The σ+ plot was not simply bilinear but widely scattered, giving a split pattern of parallel curves with significant gaps. Since any mechanistic transition with substituents should bring about a single continuous curve when plotted against an appropriate substituent constant scale, the split σ+ plot is not in line with an interpretation in terms of a mechanistic transition. On the other hand, the LArSR plots with r = 1·3 coalesced into a single smooth curye including the meta correlation curve. A different resonance demand as high as r = 1·3 is required in order to give a smooth single-curve correlation for the entire substituent range without splitting. For the reactive substituents down to p-halogens, a sufficiently linear plot can be obtained against a set of substituent constants with r = 1·3 which can be referred to the substituent effect correlation for the kc mechanism of this system. An identical r value was likewise assigned for the kc mechanism of the hydrolysis for a more severely restricted range of activating substituents down to the 4-MeS-3-CN group.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030706
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  • 80
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    N-Carbeniopyridinium salts: Charge-transfer complexes with the C5 (COOMe)5 anion; C—C bond formation with the TCNQ radical anion (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 459-469 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: N-[2,3-Bis(dimethylamino)cyclopropenylio]- and N-(tetramethylamidinio)pyridinium salts (trifluoromethanesulphonates and tetrafluoroborates) form 1:1 and 1:2 charge-transfer complexes with the pentakis(methoxycarbonyl)cyclopentadienide anion. The x-ray crystal structures of 1-[2,3-bis(dimethylamino)cyclopropenylio] pyridinium pentakis(methoxycarbonyl)cyclopentadienide tetrafluoroborate hydrate and of 1-[2,3-bis(dimethylamino)cyclopropenylio] pyridinium bis[pentakis(methoxycarbonyl)cyclopentadienide] were determined. In constrast, the tetra-cyano-p-quinodimethane (TCNQ) radical anion reacts with the first-mentioned salts by C—C bond formation to give novel dicationic salts. Thereby, the radical anion attacks the pyridinium γ-position of the N-(tetramethylamidinio)-pyridinium dication, but the three-membered ring of the N-[2,3-bis(dimethylamino)cyclopropenylio] pyridinium system.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030708
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    Evidence for formation of 2-nitrobenzoylperoxy radical generated from 2-nitrobenzoyl chloride and superoxide: Spin trapping of the peroxyradical intermediate and its oxidizing abilities (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 482-484 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 2-Nitrobenzoyl chlorde was reacted with superoxide in acetonitrile to form 1 2-nitrobenzoylperoxy radical intermediate which showed a stronger oxidizing ability than that from superoxide, as confirmed by ESR spin trapping studies.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030711
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    Kinetics and mechanism of acid hydrolysis of 2-carboethoxypyridine N-oxides (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 489-492 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Rate constants and activation parameters have been measured for the acid hydrolysis of six 2-carboethoxypyridine N-oxides. The correlations of log kobs. vs Hammett's constants and chemical shifts of intramolecular hydrogen-bonded protons in parent acids are analysed. Evidence was found for the participation of intramolecular hydrogen bonding in the hydrolysis of the esters.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030802
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    Origin of exo selectivity in norbornene. An ab initio MO study (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 519-533 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The geometries of the reactants, the reactant π-complex, the transition state and the product for exo and endo addition of BH3 to norbornene were optimized at the HF/3-21G level, and their energies were calculated at the MP2/6-31G level. The analysis of activation energy and model calculations singled out the endo deformability, a major portion of the norbornene deformation energy, as the origin of exo selectivity; norbornene, with the olefinic hydrogens already bent toward endo in the equilibrium geometry, requires less deformation to reach the exo than the endo transition state. The reason why olefinic hydrogens are bent in norbornene has been elucidated. An analysis indicates that the difference between norbornene exo side and bicyclo [2.2.1] hex-2-ene is also dictated by the endo deformability.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030806
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    Masthead (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030901
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    Interpretation of 1H NMR spectra of 2-benzopyrylium salts with the use of the CNDO/2 method (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 575-580 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The 1H NMR spectra of eleven substituted 2-benzopyrylium salts are interpreted with the aid of the CNDO/2 method for standard geometry. Some effects of the substituents are considered for the charge distribution in the 2-benzopyrylium cation.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610030904
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    Frequency-dependent branching ratio in the infrared multiphoton photochemistry of diethyl carbonates (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 567-574 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Unimolecular decomposition of 0·1 Torr of diethyl carbonate, diethyl-d5 carbonate and diethyl-d10 carbonate induced by irradiation with a CO2 TEA laser was investigated. In all cases only ethylene, ethanol and CO2 were obtained. In the case of diethyl-d5 carbonate, both ethylene-d4 and ethylene-d0 were observed together with the corresponding isotopic variants of ethanol. The chemical branching ratio was determined as a function of irradiation frequency and laser fluence by analysis of the ethylene-d0/ethylene-d4 ratio. RRKM theory applied to the branching ratio data requires very different average energies for two sets of fluence and frequency conditions that give identical total yields.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610030903
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    NMR spectroscopic study of configurations and conformations of 5-pyridylmethylenehydantoins (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 559-566 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Nine 5-pyridylmethylenehydantoins were prepared. Each of the 1-methyl-substitute compounds was obtained in two stereoisomeric forms. Only one form of each of the 3-methyl-substituted and N-unsubstituted compounds was obtained directly from synthesis but could be partially converted into the other stereoisomer photochemically. The Z/E configurations and the conformational relationship between the pyridine and hydantoin rings were studied by 1H and 13C NMR spectroscopy, including variable-temperature 1H NMR. The existence of N—H…N or C—H…N interactions and the possibility of tautomerism are suggested for some of the compounds. The Z-isomers of compounds with 2- or 3-pyridyl rings prefer an s-cis conformation whereas the E-isomers prefer an s-trans conformation.
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    URL: http://dx.doi.org/10.1002/poc.610030902
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  • 88
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    Borohydride reduction of alkyl phenyl ketones within a reversed-phase liquid chomatographic column (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 594-598 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reductions of propiophenone and octanophenone to 1-phenylpropan-1-ol and 1-phenyloctan-1-ol, respectively, with sodium borohydride and tetrabutylammonium borohydride were performed on a reverse-phase highperformance liquid chromatographic (HPLC) column of macroporous 10-μm poly(styrene-divinylbenzene) undr HLPC conditions. In these reactions a lower concentration of tetrabutylammonium borohydride than of sodium borohydride was needed to effect the same extent of reduction, and modest substrate selectivity was obtained.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030907
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  • 89
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    Electronic absorption spectra of aliphatic diamine radical cations. Conformation-dependent charge delocalization (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 606-610 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Electronic absorption spectra of radical cations generated by steady-state and pulse radiolysis from a series of α,ω-diaminoalkanes (R2N(CH2)nNR2; n = 1-6, R = CH3 or C2H5), 1,4-dimethylpiperazine and 1,4-diazabicyclo [2.2.2] octane (DABCO) were measured. In some cases spectral evidence was obtained for an interaction between the nitrogen atoms leading to charge delocalization in the radical cation. A delayed formation of radical cations was associated with a conformational change necessary for achieving the most stable structure having a favourable conformation for charge delocalization.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030909
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  • 90
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    General-acid, specific-base and intramolecular catalysis of the dehydration step in nitrone formation from furfurals and phenylhydroxylamine (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 620-626 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Nitrone formation from furfural and 5-nitrofurfural with phenylhydroxylamine was studied in water at 25°C and ionic strength 1·0 (KCl). The reaction exhibits general acid catalysis (α = 0·52), specific base catalysis and a pH-independent process. The results are consistent with a mechanism where dehydration of an N,N′-dihydroxy addition intermediate, formed by a rapid pre-equilibrium, is the only rate-determining step over the pH range studied (1-11). In contrast, nitrone formation from p-chlorobenzaldehyde and N-methylhydroxylamine exhibits a clear change of rate-determining step, from dehydration of the addition intermediate to attack of the nucleophile on the aldehyde, with increase in pH. The profile of log k2 (k2 = second-order rate constant) vs pH indicates, by comparison with the corresponding profile for similar reaction, that phenylhydroxylamine exhibits unexpected nucleophilic behaviour in this reaction. The pH-indpendent dehydration process, which has a higher rate constant than that predicted from the Brønsted line for the water catalysis, appears to involve intramolecular catalysis rather than bifunctional catalysis by water.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030911
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  • 91
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    Rearrangement and cyclization in the ionization of the 4-chloro-3-methylbutanoyl cation (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 639-642 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The second ionization of the 4-chloro-3-methylbutanoyl ion forms a primary alkyl acyl dication, as a tight ion pair. Methyl and hydrogen shifts occur to comparable extents indicating that the relative stability of the product (sec- or tert-carbocation) does not influence the energy barrier for the shift. The product of methyl shift (1,3-sec-alkyl acyl dication) loses the proton closest to the counterion in the tight ion pair and forms the pent-3-enoyl cation. Protonation-deprotonation of the latter, followed by internal acylation, gives the protonated cyclopent-2-enone. The dication resulting from hydrogen shift loses a proton from C-2 and gives the 3-methylbut-2-enoyl cation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610031004
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  • 92
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    Electrochemical and photoelectronic spectral study of compounds with high ionization potentials: Anodic oxidation of vinyl triflates in aprotic solvents (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 670-676 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Microelectrodes can be used to measure redox half-wave potentials in aprotic solvents containing no purposely added supporting electrolyte. By employing an electrode of sufficiently small size, the accessible potential range in solution is considerably extended. The electrochemical oxidation of vinyl (enol) triflates, which are oxidized at high electrode potentials, can therefore be studied using an ultramicroelectrode. Oxidation and ionization potentials, determined by ultramicroelectrode voltammetry and He I photoelectron spectroscopy, respectively, of 2-methylprop-1-enyl, cyclohexenyl, cyclopentenyl, 1,1-diphenylethenyl and prop-2-enyl triflate are reported. The results from electrochemical measurements and photoelectron spectra were compared.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610031008
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  • 93
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    Micellar catalysis of organic reactions. 28For Part 27, see T. J. Broxton and R. P.-T. Chung, J. Org. Chem. 55, 3886 (1990).. A comparison of the catalytic effects of micelles containing bromide and fluoride counterions on some SNAr AND BAc2 reactions (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 677-683 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The catalytic effects of micelles of cetyltrimethylammonium bromide (CTAB) and fluoride (CTAF) on several SNAr and BAC2 reactions were studied. Rate versus detergent concentration curves predicted by the pseudophase models PPIE (ion exchange) for CTAB studies and PPMA (mass action) for the CTAF studies were fitted to the experimental results to determine the best values of the substrate binding constant (Ks), the second-order rate constant for reaction in the micelles (K2M) and the exchange constant KOH/X (PPIE) or binding constant (PPMA) for the counterions. Better catalysis by micelles of CTAF is shown to be due to the combined effects of a more favourable exchange constant in CTAF than in CTAB, slightly different rates of reaction within the two micelles and different values of β, the fraction of micellar head groups neutralized in CTAF and in CTAB.In both micelles the magnitude of catalysis depends on the charge produced in the intermediate complex and the presence of electron-withdrawing groups to stabilize that charge. Strongest catalysis was found for a reaction leading to a monoanionic intermediate complex in which the charge was stabilized by two nitro groups, and the weakest catalysis was found for a reaction leading to a dianionic intermediate in which no electron-withdrawing groups were present.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610031009
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  • 94
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    Masthead (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610031101
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  • 95
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    Comparison between some semi-empirical and ab initio Hartree-Fock models for the description of amides (formamide revisited) (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 711-722 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A comparative study on the use of the MINDO/3, MNDO and AM1 semi-empirical methods for the description of formamide and aliphatic amide systems is reported. For formamide, ab initio Hartree-Fock calculations are also reported using both the STO-3G and 3-21G basis sets, as well as a basis set obtained by a minimal relaxation of the STO-3G contraction scheme. It is shown that both the MNDO and the STO-3G methods cannot properly reproduce the experimental results. In both cases this appears to be due to inadequacies of the basis sets used. Again in both cases only small improvements in the basis set necessary to allow for the diffuse character of the pπ orbitals lead to dramatic improvements in the calculated results. In the case of the STO-3G basis set this is demonstrated by the fact that a small relaxation in the contraction leads to results even superior to those with the 3-21G set. The conclusions reached for amide systems can be extended to other systems where planarity around or inversion with respect to nitrogen is an issue. This is demonstrated for ammonia.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610031104
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  • 96
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    Absolute rate constants for the reactions of phenylhalocarbenes with alkynes (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 760-763 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Additions of phenylchlorocarbene and phenylfluorocarbene to representative alkynes are rapid (106-107 l mol-1 s-1). The variation of the rate constants with alkyne structure parallels that observed with analogous alkene substrates. The addition of phenylchlorocarbene to 3-hexyne is characterized by a very low activation energy (∼ 2 kcal mol-1) and a large, negative entropy of activation (∼ -20 e.u.).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610031111
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  • 97
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    Masthead (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610031201
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  • 98
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    Kinetics of oxidation of amino acids by alkaline hexacyanoferrate(III) (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 799-802 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the oxidation of α-amino acids (glutamic acid and aspartic acid) by alkaline hexacyanoferrate(III) were studied at constant ionic strength and over the temperature range 323-348 K. The rate was dependent on the first power of the concentrations of substrate and oxidant, but was independent of the concentration of alkali in the range studied. The value of kH/kD was in the range 8·1-8·3 for the slow step, indicating the loss of a hydrogen atom from the C—H bond, giving a radical species which was characterized by ESR spectroscopy. The reaction proceeds by way of the α-imino acid, formed in a fast step, which undergoes hydrolysis to give the corresponding α-keto acid.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610031205
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  • 99
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    Solvation of indenyllithium and indenylpotassium studied by 13C NMR spectroscopy (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 9-12 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polarization of the π-electron systems of indenyllithium (In -Li+) and indenylpotassium (In -K+), which is generally indicative of the degree and tightness of contact ion pairing, was investigated by 13C NMR spectroscopy. The effect of changing solvent is about two thirds as great for In -K+ as for In -Li+. The indenyl anion is more strongly polarized with Li+/dimethyl sulfoxide than with Li+/ammonia, whereas the reverse is observed for In -K+. Complexation of In -K+ in tetrahydrofuran (THF) by cryptand(2,2,2) results in a π-electron distribution identical with that of In -Li+ in hexamethylphosphoramide, indicative of solvent- or agent-separated ion pairs or free ions. Small but significant cation-anion interactions are observed for In -K+ in hexamethylphosphoramide and for In -N+Me4 in THF.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030103
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  • 100
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    Structure and stability of 2σ/1σ* three-electron-bonded radical cations from 1,n-bis(alkylthio)alkanes in aqueous solutions (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 17-22 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A large number of 1,n-bis(alkylthio)alkanes, R′S(CH2)nSR″, was investigated by pulse radiolysis in aqueous solutions. The sulphur-centred radical cations, which were obtained on oxidation of the dithia compounds by ·OH radicals, are stabilized via 2σ/1σ* three-electron interaction between two sulphur atoms. Intramolecular stabilization is the only process observed for n = 2-4, whereas for longer chain compounds with n 〉 4 some intermolecular sulphur-sulphur interaction is also indicated. The stability and yields of the three-electron-bonded species also depend on the nature of the substituents R′ and R″, and for the intermolecular systems are a function of solute concentration. The results corroborate earlier investigations and demonstrate, in particular, that the optical parameters are a very sensitive measure of changes in electron density and structure of the three-electron-bonded systems.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030105
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