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  • 1
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 225-233 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The potential of using indigenous microorganisms in beach sediments to degrade petroleum hydrocarbons emanating from marine oil spillages in the Straits of Singapore was investigated. A field trial was conducted using oil contaminated beach sediments from Pulau Semakau - a small island 15 km south of Singapore. The results clearly show that the addition of inorganic nutrients to beach sediments significantly enhanced the activity of indigenous microorganisms (measured using the dehydrogenase enzyme assay and viable cell count techniques), as well as the removal of total recoverable petroleum hydrocarbons (TRPH) over a 50-day study period (with up to 44% in the case of nutrient addition). The potential of exploiting in-situ bioremediation techniques for oil spill clean-up operations in tropical marine environments is discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The biosynthesis of bacterial cellulose by Acetobacter xylinum was optimized by numerically finding the maximum of an arbitrarily chosen second order polynomial model function of several variables (describing the dependence of the cellulose production on the concentrations of the medium components), using multivariable linear regression analysis. The chosen function appeared to describe the analyzed correlation sufficiently well. Consequently, three to six stages of optimization made the determination of the optimum medium compositions possible for 16 days of fermentation at 30°C in a medium based on fructose (wt%: fructose, 3.68; yeast extract, 5.02; (NH4)2NO3, 0.001; KH2PO4, 0.3; MgSO4 × 7 H2O, 0.05; resulting in a cellulose production equal to 0.505 wt.% - namely 5.6 times higher than before the optimization) and for 7 days fermentations at 30°C in a medium based on sucrose and ethanol (wt.%: sucrose, 5.0; ethanol, 1.36; yeast extract, 1.27; (NH4)2SO4, 0.5; KH2PO4, 0.3; MgSO4 × 7 H2O, 0.05; resulting in a cellulose production equal to 0.251 wt.% - namely 1.5 times higher than before the optimization).
    Additional Material: 1 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 91-100 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The stability of a polyphenol oxidase (PPO) preparation from the white-rot fungus Trametes versicolor during a process for the enzymatic decrease of the phenolic content of commercial canola meal (CM) was investigated. The effects of temperature, pH, protein origin and concentration, and meal particles were considered. The results showed that the thermal stability of the enzyme preparation was significantly increased in the presence of CM. The half-life times for the enzyme preparation, pre-incubated with CM at 50, 60, 70 and 75°C, were 45, 10.5, 3.5 and 1.5 hours, respectively; this represents an increase in the thermal stability of the enzyme preparation of up to four times in the presence of CM compared to the stability in the absence of CM. This effect was caused by the protective actions of both the CM particles and CM proteins, with the former responsible for 90% of the observed effect. The thermal stability of the enzyme in the presence of CM, from which 20% of the extractable proteins was extracted, was 5% lower compared to the stability in the presence of untreated CM. Changes in pH level from 5.0 to 3.2 resulted in a loss of stability comparable to that observed when the pre-incubation temperature was increased from 50 to 70°C.A semi-empirical model describing the changes in the concentration of the active enzyme pre-incubated in the presence and absence of CM at various incubation temperatures was proposed. A very good agreement between the model and experimental data was obtained. The proposed model, together with a general set of model parameters, can be used as a tool for the optimization of a process for the upgrade of CM by enzymatically decreasing the meal's phenolic content.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 111-145 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A non-comprehensive review of several technical developments in the field of aerobic biological waste-water treatment engineering is carried out, considering the active role the engineers have to play in this field. This paper brings together conventional and advanced problems in the field of aerobic biological waste-water treatment.Such an overview of biological waste-water treatment also precedes comments on some important aspects concerning the microorganisms responsible for waste-water treatment as well as considerations of the application of fundamentals and kinetics to the analysis of the biological processes used most commonly for aerobic biological waste-water treatment.A survey of the development of the biological activated-sludge process and some modifications are given. Some problems implied in the conventional activated-sludge waste-water treatment are analyzed, considering conventional processes and bioreactor models (the continuous stirred-tank reactor model and the plug-flow reactor models of the activated-sludge process) as well as aerated lagoons.Further, modifications of the activated-sludge process are presented. These include additional details on the bioreactor progress and applications, with emphasis on aspects concerning airlift bioreactors and their variants, deep-shaft bioreactors and reciprocating jet bioreactors which are considered as the third generation of bioreactors owing to their important advantages in design, operation and performance in waste-water treatment. Sequencing-batch reactors and aerobic digestion processes, including conventional aerobic digestion, high-purity oxygen digestion, thermophilic aerobic digestion and cryophylic aerobic digestion are also reviewed.Finally, some aspects regarding the operational factors that are involved in the selection of the reactor type are included.
    Additional Material: 11 Ill.
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  • 5
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the first part of the experiments, the mechanical properties of 1%, 2% and 3% carrageenan and 1%, 2% and 3% carrageenan/locust bean gum (LBG) gels stored in various concentrations of propionic and acetic acids and their mixtures were examined. The stability of these materials was measured by uniaxial compression between two parallel plates using the Instron Universal Testing Machine. A mathematical model explaining the dependence of the destroying force on the storage time was chosen for data analysis. Using this model, the average rate of gel deterioration was calculated. The structural properties of the examined gels were most influenced by the highest concentration of propionic and acetic acids and their mixtures (1% acetic acid and 2% propionic acid). The addition of LBG to carrageenan decreased the gel destroying force and increased its resistance to acids.In the second part of the experiments, the Propionibacterium freudenreichii subsp. shermanii NCFB 1081 and NCFB 566 were immobilized in a living state in 1%, 2% and 3% carrageenan and 1%, 2% and 3% carrageenan/LBG gels. The ammonia consumption, glucose utilization, production of propionic and acetic acids and the biosynthesis of vitamin B12 were examined. An increase in the productivity of propionic acid and a significant decrease in the vitamin B12 produced in the biosynthesis were observed when immobilized cells were used. The immobilization of cells enhanced the productivity of propionic acid by up to 40% compared to free cells. The best results were obtained for the second and third applications of immobilized cells in all concentrations of carrageenan gels and 2% and 3% carrageenan/LBG gels The results showed that carrageenan/LBG is a better support material for the immobilization of propionic acid bacteria than the pure carrageenan.
    Additional Material: 2 Ill.
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  • 6
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 171-177 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The bioaccumulation of cadmium by the white rot fungus Pleurotus sajor-caju onto dry biomass was investigated using aqueous media with concentrations in the range of 0.125 mM-1.0 mM The highest cadmium uptake (between 88.9 and 91.8%) was observed with aerobic fungal biomass from the exponential growth phase. Up to 1.0 mM cadmium gradually inhibited mycelium development, but never blocked it completely. Freeze-dried, oven-dried and non-metabolizing live Pleurotus sajor-caju biomass types were tested for their capacity to adsorb the test ion Cd2+ within the pH range of 4.5 to 6.0. Freeze-dried biomass proved to be the most efficient biomass type for Cd2+ metal adsorption. Therefore, Pleurotus sajor-caju may be used for heavy metal removal and bioremediation.
    Additional Material: 2 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 3-16 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of cellobiose hydrolysis was studied using β-glucosidase from Penicillium funiculosum, both free and immobilized on nylon powder, at different temperatures, pH values, enzymatic activities and initial cellobiose and glucose concentrations.The experimental results were fitted to a kinetic model by considering the substrate and product inhibitions as well as the thermal deactivation of β-glucosidase with a mean deviation of less than 10%. The immobilization of β-glucosidase led to an increase in the stability of the enzyme against changes in the pH value.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 27-36 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ethanol has been reported to be a gaseous pollutant, originating from the agricultural industry. Interest in its biodegradation has increased over the last two decades. Most of the current studies have focused on its elimination by mixed cultures. This study is part of a broader project intended to utilize Candida utilis strains for gaseous ethanol elimination and to eventually bioconvert them into biomass and/or volatile metabolites. We present here the study of six strains (one from the ATCC and five from the ICIDCA collection) cultivated in a liquid medium, with initial ethanol concentrations of 16 g/l and 32 g/l. At 16 g/l, a maximum ethanol elimination rate of 0.13 g/l × h was obtained in four of the six strains (ATCC 9950, L/375-1, L/375-5 and L/375-10). This rate increased to 0.21 g/l × h with an initial ethanol concentration of 32 g/l. The L/375-5 strain was the best biomass producer (3.3 g/l) at 32 g/l, while the highest ethyl acetate production (0.80 g/l) was obtained with the L/375-1 strain. The L/375-25 and L/375-26 strains which showed very low ethyl acetate production were, by way of contrast, efficient acetaldehyde producers, with 0.54 g/l and 0.66 g/l measured in the broth. While biomass production reached its maximum after two days of culture, the production of acetic acid and ethyl acetate continued during the third day. The results for biomass and metabolite production obtained with the ICIDCA collection strains (L/375-1, L/375-5 and L/375-10) were better than those obtained with the ATCC 9950 strain, although the latter often has been reported to be particularly suitable for metabolite production.
    Additional Material: 5 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 77-78 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 59-68 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The ability of the Rhizobium sp., isolated from the root nodules of the leguminous pulse yielding shrub Cajanus cajan, to produce extracellular polysaccharides (EPS) was checked. A large amount of EPS (1, 128 μg/ml) was produced by the bacteria in yeast extract mannitol medium. Growth and EPS production started simultaneously, but the production reached its maximum level in the stationary phase of growth at 28 h. The EPS production by this Rhizobium sp. was much higher than by many other strains from nodules of Cajanus cajan which took a much longer time to reach maximum EPS production than this strain. The maximum EPS production (2,561 μg/ml) was obtained when the medium was supplemented with mannitol (1%), cetyl pyridinium chloride (2 μg/ml) and KNO3 (0.2%), in which the production was increased by 276% compared to the control. The EPS production rose in the period up to 65 h with increased mannitol concentration. The EPS contained arabinose, xylose and rhamnose monomers. The possible role of rhizobial EPS production in root nodule symbiosis is discussed.
    Additional Material: 3 Ill.
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  • 14
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 15
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 331-339 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Rhizobium sp., isolated from the root nodules of the leguminous fodder herb Melilotus alba, produced large amounts of extracellular polysaccharides (EPS) (963.5 μg/ml) in a yeast extract mannitol medium. Growth and EPS production started simultaneously, but EPS production reached its maximum during the stationary phase of growth of the bacteria, at 20 hours. EPS production was increased with all of the thirteen sugars tested. Different nitrogen sources, such as nitrates, glutamic acid, casamino acid and L-asparagine, increased the EPS production although it was inhibited by glycine, nitrite and ammonium salts. Among the vitamins and metal ions, only pyridoxal phosphate and ZnSO4 promoted EPS production. Attempts were made to optimize the cultural requirements for growth and maximum EPS production. Maximum EPS production (1457.0 μg/ml) was obtained when the medium was supplemented with glucose (1%), pyridoxal phosphate (2 μ g/ml), ZnSO4 × 7 H2O (10 μg/ml) and glutamic acid (0.1%). Under these conditions, the production was increased by 254.3% compared to the control. The EPS contained arabinose, xylose and rhamnose monomers. The presence of arabinose and xylose in the EPS produced by a Rhizobium sp. was uncommon.
    Additional Material: 2 Ill.
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  • 17
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the present work, the use of flame-burned WS as carriers of Z. mobilis and extracellular levansucrase and the effect of the cell fixation method by dehydration on system productivity were investigated. Lyophilization and convective drying of Z. mobilis biomass at 30°C to a moisture content of 10-14% gave the best results for the repeated batch fermentations of a sucrose medium to obtain levan and ethanol. Significant correlation between the product formation and the concentration of free cells in the fermentation medium was established. Clearly, the cells were weakly bound to the newly generated WS and were washed out into the medium during fermentation. Here the hypothesis is presented that components excreted from damaged cells during dehydration can intensify the reactivation of damaged living cells and influence the interactions between the cells and the wire surface.The passive immobilization of extracellular levansucrase in oxidized WS was also observed. The superiority of oxidized WS in comparison with non-treated WS is related to an increase in the number of OH groups. The potential regeneration of WS by burning after the termination of fermentation cycles was also considered.
    Additional Material: 2 Ill.
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  • 18
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 146-146 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 157-161 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A xylanase was removed from crude extract of the fungus Penicillium janthinellum under optimized conditions: 0.10M phosphate buffer, pH 7.0, 0.2 M BDBAC (N-benzyl-N-dodeceyl-N-bis (2-hydroxyethyl) ammonium chloride), 7.5% hexanole, 30°C and an agitation time of 1 minute. At 1.42 mg per ml protein concentration, 73% of the xylanase activity was recovered and a 7-fold enrichment factor was obtained. The enzyme had a molecular weight (MW) of 20.1 kDa and the isoelectric point (PI) revealed the presence of two protein bands with a PI of 6.0 and 6.5. The optimum pH and optimum temperature were 4.2 and 50°C, respectively. The low pH differential between the aqueous medium and the protein PI seemed to influence the xylanase transportation into the reversed micelles.
    Additional Material: 2 Tab.
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  • 20
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 21
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 163-169 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The morphogenetic response of Hypericum perforatum seedlings to different auxin and cytokinin concentrations was studied. A stimulation of the concentration-dependent rooting ability was observed under the influence of indole-3-acetic acid and indole-3-butyric acid. Rooting was not enhanced by the effects of 2,4-dichlorophenoxyacetic acid and 1-naphtaleneacetic acid. Differentiated roots were isolated and cultured in liquid media with the same combination of growth-promoting auxins. Chromosome counts in root tip cells after long-term cultivation indicated a high degree of chromosomal instability. Multiple shoot formation occurred under the influence of 6-benzylaminopurine and kinetin. Adenine and 6-(γ,γ-dimethylallylamino)-purine did not stimulate shoot differentiation. No differences in the morphogenetic response to auxins and cytokinis were detected between diploid and tetrapoloid plants.
    Additional Material: 2 Ill.
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  • 22
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 23
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 179-186 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Spores of Aspergillus niger were exposed to a pulsed electric field. After treatment by the electric field, the viability of the conidia of A. niger varied depending on the field strength, pulse width and frequency. In all cases, these parameters reduced the viability rate of the conidia from 2.0 × 107 to a range from 6.2 × 106 to 8.5 × 106 spores/ml (3.1 to 42.6%). After pulse treatment, the conidia were used as the inoculum for citric acid fermentation in shake flasks. The highest increase in citric acid yield (about 1.4-fold) was reached at a field strength of 2.85 kV/cm, a frequency of 1 Hz and a pulse width of 1 ms. When the parameters of the electric field increased there were important changes in the respiration rate of the Aspergillus niger mycelium (48-h-old) after electric shock treatment. The highest consumption of dissolved oxygen (22.9%) in the medium by Aspergillus niger mycelium was observed at an electric field strength of 2.85 kV/cm, a 1 Hz frequency, a pulse width of 1 ms and a 1-min exposure period. It seems that an electric-field stimulation of the conidia prior to inoculation may offer an important method of improving the efficiency of citric acid. The treatment of the conidia is both simple from the technical point of view and extremely rapid.
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  • 24
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 25
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of adding some inducers of lignolytic activity to semi-solid-state cultures of Phanerochaete chrysosporium BKM-F-1767 (ATCC 24725) were investigated. The inducers assayed were veratryl alcohol and solid manganese (IV) oxide. The microorganism was cultured on corncob, which functioned both as physical support and source of nutrients.Supplementing the cultures with veratryl alcohol created the situation where manganese-dependent peroxidase (MnP) and lignin peroxidase (LiP) activities of approximately 1,500 U/l and 200 U/l, respectively, could be attained. These activities were considerably higher than those obtained in the reference cultures (about 5 and 4-fold).In the same way, the addition of manganese (IV) oxide led to MnP and LiP activity levels of about 2,000 U/l and 300 U/l, respectively. These activities were also notably above (about 6 and 5-fold, respectively) those achieved in the reference cultures.Moreover, laccase activity (around 200 U/l) was only detected in veratryl alcohol or manganese (IV) oxide supplemented cultures.
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  • 26
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 27
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 45-56 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The culture behaviour of Thermus aquaticus was characterized. The response of the bacterium to various carbon (tryptone, glucose, glycerol) and nitrogen sources (yeast extract, NaNO3, (NH4)2SO4, leucine, thymine, thiamine, glutamic acid) was studied. Amino acids did not support growth, but CASTENHOLZ salt medium supplemented with yeast extract and glucose or tryptone resulted in good growth and production. A suitable medium composition giving the highest biomass concentration and enzyme yield was developed. The simple medium containing TYE-NaCl resulted in the highest biomass concentration, whereas CASTENHOLZ mineral medium supplemented with tryptone and yeast extract gave the highest specific activity and enzyme yield. The effect of inoculum age and size on growth was also investigated in order to improve the yield and process consistency. The use of shake flasks inoculated with precultures at their early or late stationary phase resulted in the same biomass concentration (0.56 ± 0.015 g/l) and similar maximum specific growth rates (0.258 ± 0.003 h-1). Inoculum sizes between 1 and 2.5 per cent were optimal for cell growth. As the other papers on thermophilic microorganisms, including the T. aquaticus YT-1 strain, gave qualitative information on growth, the results presented here cannot be compared with others on a quantitative basis. TaqI endonuclease was purified using a 5 step protocol including cell disruption, adsorption, precipitation, column chromatography and final dialysis. The enriched fraction had a specific activity of 33,600 U TaqI endonuclease per mg protein.
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  • 28
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 88-88 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 29
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 79-86 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Methylobacterium rhodesianum MB 126, a pink-pigmented facultatively methylotrophic bacterium that uses that serine pathway for the assimilation of reduced C1 compounds, is able to produce poly-3-hydroxybutyrate (PHB) under certain limitation conditions. Mutants of this bacterium, which were isolated after the treatment with sodium nitrite, are impaired in their ability to synthesize PHB, but produce another polymer in addition to PHB, namely an exopolysaccharide (EPS). This paper attempts to explain this surprising behaviour.
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  • 30
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 31
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 32
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 37-44 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Agar-agar, agarose, carrageenan and calcium alginate were used for the immobilization of Dunaliella salina cells. Out of the four, agar-agar was found to be the most effective and therefore the study was carried out on it using different pH values ranging from 6 to 10 and cell densities from 0.1 to 0.8 μg chlorophyll (chl, a) per bead to find which are is best suited for glycerol production. The maximum glycerol production of 9.2 μM/mg chl a was recorded in agar-agar immobilized algae and this was followed by 8.4 μM/mg chl a in calcium alginate. The maximum cell number 6.2 × 109/ml and the specific growth rate (μ) of 0.80 l/day were reached at pH 8 in agar-agar immobilized algae. It was shown that the maximum amount of glycerol was produced when the cell density was 0.8 μg chl a/ block. Changing the medium after 24 hours affected the rate of glycerol production at different pH values. Using a cell density of 0.8 μg chl a/block at 16 W/m2 light intensity increased the glycerol production in comparison with the use of free living cells.
    Additional Material: 4 Ill.
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  • 33
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 235-250 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new low-cost β-galactosidase (lactase) preparation for whey permeate saccharification was developed and characterized. A biocatalyst with a lactase activity of 10 U/mg, a low transgalactosylase activity and a protein content of 0.22 mg protein/mg was obtained from a fermenter culture of the fungus Penicillium notatum. Factors influencing the enzymatic hydrolysis of lactose, such as reaction time, pH, temperature and enzyme and substrate concentration were standardized to maximize sugar yield from whey permeate. Thus, a 98.1% conversion of 5% lactose in whey permeate to sweet (glucose-galactose) syrup was reached in 48 h using 650 β-galactosidase units/g hydrolyzed substrate. After the immobilization of the acid β-galactosidase from Penicillium notatum on silanized porous glass modified by glutaraldehyde binding, more than 90% of the activity was retained. The marked shifts in the pH value (from 4.0 to 5.0) and optimum temperatures (from 50°C to 60°C) of the solid-phase enzyme were observed and discussed. The immobilized preparation showed high catalytic activity and stability at wider pH and temperature ranges than those of the free enzyme, and under the best operating conditions (lactose, 5%; β-galactosidase, 610-650 U/g lactose; pH 5.0; temperature 55°C), a high efficiency of lactose saccharification (84-88%) in whey permeate was achieved when lactolysis was performed both in a batch process and in a recycling packed-bed bioreactor. It seems that the promising results obtained during the assays performed on a laboratory scale make this immobilizate a new and very viable preparation of β-galactosidase for application in the processing of whey and whey permeates.
    Additional Material: 6 Ill.
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  • 34
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 35
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 263-272 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: An acid α-amylase hyperproducing strain, designated as MIR-61, was isolated in a screening procedure from South American soil samples. MIR-61, a 60°C thermoresistant strain, was identified using 98 biochemical and morphological tests and characterized as Bacillus licheniformis by numerical taxonomy. Batch cultures of B. licheniformis MIR-61 showed extracellular α-amylase and α-glucosidase activities during the exponential growth phase.The production of α-amylase was studied at free and constant pH values at 37 and 45°C. Maximum α-amylase activity (4,767 kU/dm3 in a liquid medium) was detected at 45°C at a constant pH (7.0) in the late exponential phase. The α-amylase production by B. licheniformis MIR-61 is 10 to 300 times higher than the enzyme production reported in strains of the same species.Optimum α-amylase activity was found at 50 to 67°C in an acid pH range from 5.5 to 6.0. These properties would allow its use in starch industry processes.
    Additional Material: 4 Ill.
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  • 36
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 37
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 38
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 279-292 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The continuous aerobic degradation of phenoxyalkanoate herbicides by Sphingomonas herbicidovorans MH was investigated in a bubble reactor filled with modified polyurethane-foam (PU 90/51) as a carrier for the adsorptive immobilization of the bacterial cells. The PU-foam was applied in the form of plates (5 × 10 × 10 mm) and the amount added was equivalent to a PU-load of 1.25% [w/v]. Strain MH is capable of detoxifying the dichloro-substituted phenoxyalkanoates 2,4-DP, 2,4-D and 2,4-DB and the methylchloro-substituted phenoxyalkanoates MCPA, MCPP and MCPB. Degradation of the respective substrate was followed by HPLC analyses and by determination of the chloride release. No intermediates of the degradation pathways or “dead end” products were detected by HPLC analyses. The PU-bubble reactor with immobilized 2,4-DP-pre-grown cells was run continuously at 30°C at the high dilution rate of D = 0.5h-1 with 2,4-DP (0.2 g/l), and with subsequent changes to each of the other phenoxyalkanoates as a single substrate in the feed and with an intermittent return to 2,4-DP. Finally, after an intermediate substrate accumulation, 2,4-D, 2,4-DP, MCPA and MCPP could be degraded under the aforementioned conditions corresponding to a maximum degradation rate of Qphen = 100 mg/l × h. In the case of 2,4-DB, a slightly reduced conversion rate of about 94% could be calculated. In contrast to these results, 0.2 g/l of the more recalcitrant MCPB could not be metabolized at this high dilution rate of D = 0.5 h-1 by the biofilm of Sphingomonas herbicidovorans MH, but it was degradable at a reduced dilution rate of D = 0.25 h-1. Complete detoxification of a stoichiometric mixture of the dichloro- and the methylchloro-substituted phenoxyalkanoates including MCPB, respectively, at a total concentration of 0.2 g/l was achieved at D = 0.25 h-1, corresponding to a degradation rate of Qtot = 50 mg/l × h. Finally, the efficiency of the PU-immobilized cells of Sphingomonas herbicidovorans MH in detoxifying mixtures of all six herbicides could be increased to Qtot = 75 mg/l × h by the further addition of PU-foam particles corresponding to a final PU-load of 2.5% [w/v]. This PU-bubble reactor was successfully operated for more than 12 months to clean up synthetically concocted waste waters with fluctuations in phenoxyalkanoate concentration and composition.
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  • 39
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 307-318 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The biodesulphurization of Mengen lignite by a mesophilic bacterium, Rhodococcus rhodochrus ATCC 53968, was investigated in a batch stirred and aerated reactor. The experiments were carried out at 28°C with an inoculum percentage, initial pH, initial sodium acetate and lignite concentration of the biodesulphurization medium of 8% [v/v], 6.5 mM, 20 mM and 20 g/l, respectively. Variations in the sulphur contents of the lignite relative to the biodesulphurization period were monitored. The effects of the stirring and aeration rates on the removal of different sulphur forms from coal were investigated in the ranges 450-1,200 rpm and 0.1-0.53 vvm and the optimum values were found to be 500 rpm and 0.18 vvm, respectively. An increase in the total sulphur reduction with increasing biodesulphurization time was observed. The maximum total sulphur removal percentage was found to be 15.2% at 1,200 rpm after four days of incubation. The highest total sulphur removal rate was calculated on the second day of microbial desulphurization for each run. The total and organic sulphur contents of the coal after biodesulphurization were correlated with the stirring and aeration rates by using the non-linear least squares regression method. In the experimental runs lasting 8 days, the highest organic sulphur reducing percentage of 10.1% was obtained at a stirring rate of 500 rpm and an aeration rate of 0.40 vvm.
    Additional Material: 6 Ill.
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  • 40
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Selected strains of basidiomycetes (Abortiporus biennis, Trametes versicolor and Cerrena unicolor) were shown to produce enhanced extracellular peroxidase (EP), superoxide dismutase (SOD) and laccase activities following the exposure of 10-day-old fungal cultures to separate high and low temperature stress. The stressful conditions also caused an increase in the concentrations of phenol compounds and superoxide anion radicals in these cultures. At first, peroxidase activity was observed at 12 hours from the moment of temperature stress application. Laccase activity appeared at 96 hours after the maximum levels of superoxide anion radicals (48 h) and SOD activity (36-72 h). The concentration of phenolic substances grew steadily during the period of cultivation. These relations between laccase, SOD and EP as well as superoxide radicals and phenol levels in the environment of ligninolytic fungi seems to be important in the course of the biosynthesis or biodegradation of lignin, as the consequence of adaptation of these basidiomycetes to environmental temperature conditions.
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  • 41
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 356-356 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 42
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 349-355 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Comamonas acidovorans MC1, which is capable of degrading the chiral phenoxypropionate herbicides 2-(2,4-dichlorophenoxy)propionate [dichlorprop, (RS)-2,4-DP] and 2-(4-chloro-2-methylphenoxy)propionate [mecoprop, (RS)-MCPP] and of degrading the phenoxyacetate herbicides 2,4-dichlorophenoxyacetate (2,4-D) and 4-chloro-2-methylphenoxyacetate (MCPA), was investigated with respect to the enzymatic basis of this broad substrate specificity. The initial steps of the degradation pathway of (RS)-2,4-DP and 2,4-D were studied. By applying either ion exchange chromatography or hydrophobic interaction chromatography it was possible to separate two enzyme fractions with etherolytic activity, which exhibited pronounced substrate specificity. One enzyme fraction was highly specific for the degradation of the R-enantiomer of 2,4-DP and did not essentially attack the S-configuration. The other enzyme fraction showed pronounced activity toward the cleavage of the S-enantiomer and additionally utilized 2,4-D with almost equal velocity; (R)-2,4-DP was even cleaved at a low rate by this enzyme. These results confirm the existence of phenoxyalkanoatedegrading enzymes with enantiospecific properties in strain MC1.
    Additional Material: 3 Ill.
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  • 43
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 44
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 191-203 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The population of poly-β-hydroxybutyrate-degrading microorganisms and the biodegradation of PHB in local landfill soils were examined in vitro and in vivo. Forty-two PHB-degraders consisting of 12 bacteria, 25 actinomycetes and 5 moulds were isolated. The total PHB-degraders averaged 4.7 × 107 and 20 × 104 colony forming units (cfu)/g for San Mateo wet and dry soils, respectively, and 2.3 × 107 and 8.5 × 104 cfu/g for Carmona wet and dry samples, respectively. The PHB-degraders formed 0-59% of the total microbial population in San Mateo and 8-42% in Carmona. Complete (100%) degradation of PHB powder was observed for Chryseomonas-27 and Aspergillus-39 on day 5 in shake flask culture and for Streptomyces-4 on day 7. Burial test in landfill soils showed a 90-91% weight loss of PHB film strips within four weeks; the weight loss of polypropylene film strips was up to 0.12% only. Scanning electron micrographs of degraded films revealed the attachment of microbial cells and fungal mycelium and spores on the surfaces. Holes and cavities were also noted due to the microbial degradation processes.
    Additional Material: 3 Ill.
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  • 45
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 205-210 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The application of biotechnology in environmental processes is an enormous subject that could remain the topic of a university lecture course for many years. For this reason I wish to limit my lecture to a few examples and to attempt to sketch out particularly promising opportunities for future development.
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  • 46
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 47
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 213-223 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Acinetobacter sp. E11, isolated from Port Dickson Beach, Malaysia, was able to grow in media containing crude oil as the sole carbon and energy source. Substrate specificity studies showed that the bacterium exhibited substrate preference as growth was observed only in media containing aliphatic hydrocarbons, while aromatic and cyclic hydrocarbons inhibited growth. With the aliphatic hydrocarbons, growth was seen only in the long-chain alkanes tested (pentadecane, dodecane and hexadecane). No growth was recorded in the short-chain alkanes (pentane, hexane and heptane) tested. With complex hydrocarbons, only crude oil and 4T SHELL engine oil supported growth. No growth was observed in kerosene and PETRONAS gasoline. The isolate could grow in up to 10% and 20% [v/v] of the crude oil and alkanes tested, respectively. Among the long-chain alkanes tested, hexadecane was the most preferred, followed by pentadecane and dodecane. Nitrogen and phosphorous supplements were essential for growth and the best growth was achieved with 3% nitrogen/phosphorous additions. Microscopic observation revealed that the bacterium adhered to the hexadecane and crude oil droplets. GC analysis showed that the bacterium was able to degrade more than 60% of the hydrocarbons in the crude oil in 15 days at 37°C compared to the uninoculated media.
    Additional Material: 3 Ill.
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  • 48
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 49
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 50
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 293-304 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The mineralization of a non-ionic alcohol ethoxylate (AEO) surfactant was investigated over the concentration range occurring in rinsing water from surfactant production processes. For this, an experimental set-up for respirometric batch experiments was developed. The set-up and the method were validated by experiments with glucose as the single carbon source. It was possible to calculate substrate decay from the time course of exogenously consumed oxygen during respirometric batch experiments. The kinetic coefficients calculated by respirometry showed a lower standard deviation than those calculated from emasured glucose concentrations.The degradation mechanism of AEO was investigated by identification of metabolities, occurring during the mineralization process of AEO, using Flow Injection Mass spectrometry (FI-MS). It was concluded that the degradation of AEO occurs in two main steps. First, the enzymatic hydrolysis of AEO into alcohol and polythylene glycol (PEG) is performed. Second, the mineralization of both substances takes place, while the mineralization of the alcohol is faster than that of the PEG. The mineralization kinetics were investigated in respirometric batch experiments. The model used is based on double MONOD kinetics for the substrates being produced by hydrolysis (μmax1 = 0.047 h-1, Ks1 = 15 mg/l DOC for alcohol; μmax2 = 0.027 h-1, KS2 = 4 mg/l DOC for PEG). The validation of the model by calculating the results obtained from measurements in a continuously operated lab scale CSTR with bacteria recycle was successful.
    Additional Material: 8 Ill.
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  • 51
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    Acta Biotechnologica 19 (1999), S. 69-75 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: An increase in the molar growth yield (YX/S = 14.3-20.3 g/mol) on glucose (25 mM) was achieved after the transition of Zymomonas mobilis ATCC 29191 from anaerobic to aerobic steady state growth at dilution rates of D = 0.31-0.40 1/h and under oxygen-unlimited conditions. The transfer of anaerobically or aerobically grown steady state cells into a fresh medium resulted in the higher values of YX/S. A positive correlation was established between biomass and acetaldehyde yield within the range of 5-9 mM acetaldehyde in the medium. An inhibitory effect of the exogenously added acetaldehyde (Ki = 16.7 ± 2.8 mM) on the ATPase activity was observed in vitro, using cell-free extracts of anaerobically grown Z. mobilis. The results obtained provide evidence that the increased values of biomass yield could be explained by the redirection of ATP usage during aerobic growth of Z. mobilis.
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  • 52
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    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 53
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 86-87 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 54
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 55
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 101-109 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pleurotus sajor-caju (FR.) SINGER was cultivated on different organic wastes, namely sericulture waste, Populus deltoides MARSH, and Eupatorium adenophorum SPRENG. Paddy straw was taken as the control and all the data were compared with it. The mineral contents of the fruiting bodies of Pleurotus sajor-caju and the substrates on which the mushroom was grown were analyzed. Among the eight minerals determined (calcium, phosphorus, potassium, magnesium, sodium, iron, manganese and zinc), the potassium content was highest followed by phosphorus, magnesium and sodium. Analysis of the mineral contents of the substrates before cultivation had also been carried out. The mineral contents of the fruiting bodies of Pleurotus sajor-caju were found to be different on different substrates. It was also observed that the mineral contents of the fruiting bodies of Pleurotus sajor-caju increase when cultivated on substrates with higher mineral contents. The maximum mineral contents per 100 g of the substrates before cultivation were Ca - 347 mg; P - 151 mg; K - 1,805 mg; Na - 127 mg; Mg - 227 mg; Fe - 53 mg; Mn - 10 mg and zn - 3.1 mg. The mineral contents of the fruiting bodies of Pleurotus sajor-caju per 100 g ranged as follows: Ca - 25.1 mg to 35.3 mg; P - 448 mg to 602 mg; K - 2,146 mg to 2350 mg; Na - 139 mg to 229 mg; Mg - 153 mg to 224 mg; Fe - 9.74 mg to 20.75 mg; Mn - 2.5 mg to 4.0 mg and Zn - 2.2 mg to 3.1 mg.
    Additional Material: 3 Tab.
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  • 56
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 19 (1999), S. 357-363 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: An alternative microbiological method for the production of malate from fumarate is presented. The yeast Dipodascus magnusii was used for this bioconversion.The optimum cell growth temperature was 28°C and the working volume 120 ml. The highest level of fumarase activity during bioconversion was achieved at a pH of 7.5 and a temperature of 37°C. These conditions were determined as optimal. Using sodium fumarate (1M), the maximum specific productivity of malic acid obtained was 1.72 g/(gDCW × h) for intact cells. In the case of ammonium fumarate, it was 2.25 g/(gDCW × h).
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  • 57
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    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 58
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    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 59
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 60
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 61
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 19-24 
    ISSN: 0009-2940
    Keywords: Bis(diorganoboryl)chalcogenides ; Pyrazaboles ; Pyrazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Neuartige Substituierte B2ElVIN2 HeterocyclenDie Bis(diorganoboryl)chalkogenide (R2B)2O [R = C2H5 (3); R2 = 1,5-C8H14 (1)], (R2B)2S [R2 = 1,5-C8H14 (5)], und (R2B)2Se [R2 = 1,5-C8H14 (7)] reagieren mit Pyrazol (Pz) und dessen Derivaten 3-Methylpyrazol (3-MePz) und Indazol (benzo-Pz) in hohen Ausbeuten (65-92%) zu stabilen 1:1-Additionsverbindungen [z. B. 2 (El = O), 4 (El = O), 6 (El = S), 8 (El = Se)]. 1H-, 13C-, 11B-NMR-Spektren und Röntgenstrukturanalysen (von 2 und 6) zeigen eine Grundstruktur mit einem zentralen B2ElN2-Heterocyclus (El = O, S, Se). Die Reaktion von 2 mit R2BH und die Thermolyse von 4 führen zu den dimeren 1-Pyrazolylboranen 9a bzw. 9b.
    Notes: The bis(diorganoboryl) chalcogenides (R2B)2O [R = C2H5 (3); R2 = 1,5-C8H14 (1)], (R2B)2S [R2 = 1,5-C8H14 (5)], and (R2B)2Se [R2 = 1,5-C8H14 (7)] react with pyrazole (Pz) and its derivatives 3-methylpyrazole (3-MePz) and indazole (benzo-Pz) to form in high yields (65-92%) stable 1:1 adducts [e.g. 2 (El = O), 4 (El = O), 6 (El = S) and 8 (El = Se)]. 1H-, 13C-, 11B-NMR spectra and X-ray analyses (of 2 and 6) show a basic structure with a central B2ElN2 (El = O, S, Se) heterocycle. The reaction of 2 with R2BH and the thermolysis of 4 give the dimeric 1-pyrazolylboranes 9a and 9b, respectively.
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  • 62
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 31-36 
    ISSN: 0009-2940
    Keywords: Mercury - mercury contacts ; Naphthalenediylmercury compounds ; Organomercury compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Extremely Short Mercury-Mercury Contacts in peri-Dimercurated Naphthalene Compounds1-Naphthylmercury chloride (1) and 1,8-naphthalenediylbis(mercury chloride) (2) were prepared from the corresponding naphthyllithium precursors and HgCl2 in ca. 80% yield. In an alternative route, 2 can be obtained from 1,8-naphthalenediyldiboric acid anhydride and HgCl2 in 85% yield. The structure of 2·DMSO has been determined by X-ray diffraction methods. The lattice contains discrete adducts in which the two mercury atoms are bridged by the DMSO oxygen atom. The HgCl moieties are bent away from each other through distortions of the naphthalene framework and of the C—Hg—Cl axes, which results in a Hg ‥ Hg distance of 3.102(1) Å. - Symmetrization of 2, induced by treatment with NaI in aqueous ethanol, affords bis(μ-1,8-naphthalenediyl)dimercury (3). In the X-ray structure determination of this compound the shortest „non-bonding“ Hg·Hg contact reported in the literature has been detected: Hg1··Hg2 = 2.797(1) Å. The molecule also shows distortions in the naphthalene framework and in the C—Hg—C axes [C—Hg—C = 173.3(5)°].
    Notes: 1-Naphthylquecksilberchlorid (1) und 1,8-Naphthalindiylbis-(quecksilberchlorid) (2) werden aus den zugehörigen Naphthyllithium-Verbindungen und HgCl2 mit ca. 80% Ausbeute erhalten. Alternativ kann 2 auch aus 1,8-Naphthalindiyldiborsäureanhydrid und HgCl2 gewonnen werden (Ausbeute 85%). Von 2·DMSO wurde die Kristallstruktur bestimmt. Es liegen diskrete Addukte vor, in denen die beiden Hg-Atome durch das O-Atom des DMSO überbrückt werden. Die HgCl-Einheiten sind durch Verzerrungen im Naphthalingerüst, durch Winkelung der Achsen C—Hg—Cl und durch deren Auslenkung aus der Naphthalinebene voneinander weggebogen, so daß ein Hg·· Hg-Kontakt von 3.102(1) Å resultiert. - 2 symmetrisiert sich bei der Einwirkung von NaI in wäßrigem Ethanol unter Bildung von Bis(μ-1,8-naphthalindiyl)diquecksilber (3). Bei der Strukturanalyse dieser im Kristall zentrosymmetrischen Verbindung wurde der bisher kürzeste „nichtbindende“ Hg··Hg-Kontakt von 2.797(1) Å gefunden. Auch in 3 sind die C—Hg—C-Achsen abgewinkelt [C—Hg—C = 173.3(5)°], und das Naphthalingerüst ist verzerrt.
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  • 63
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 59-61 
    ISSN: 0009-2940
    Keywords: N-Butyl-N′-dansylthiourea ; Complexing agent, fluorescent ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-Butyl-N′-dansylthiourea as Fluorescent Broad-Band Complexing AgentN-Butyl-N′-dansylthiourea (2) [dansyl = 5-(dimethylamino)-1-naphthylsulfonyl] is obtained by the reaction of dansylamide (1) with butyl isothiocyanate. The compound is a stable, fluorescent complex agent for a broad spectrum of metal ions. The UV spectra and fluorescence of the ligand and some metal complexes are discussed. The fluorescence of the dansyl group is strongly affected by metal ions.
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  • 64
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 83-94 
    ISSN: 0009-2940
    Keywords: Enaminecarbaldehydes ; Enamino ketones ; hetero Diels-Alder reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese und Struktur von Enaminecarbaldehyden und Enamino KetonenDie Synthese der Enamincarbaldehyde 1a-s und 17a-c sowie der Enamino-Ketone 2a-k und deren N-Acyl-Derivate 19a-k und 21-t mit Elektronenacceptor-Substituenten an C-2 bzw an der CO-Gruppe wird beschrieben. Kondensation von 2-Formyl-3-oxopropansäure-methylester (13) mit Ammoniak und den Aminen 14b-s ergab die Enamincarbaldehyde 1a bzw. 1b-s in einer Ausbeute von 72-93%. Die Enamincarbaldehyde 17 konnten durch Formylierung von 15 mit dem gemischten Ameisensäureessigsäureanhydrid erhalten werden. Die Synthese der Enamino-Ketone 2a-k erfolgte mit einer Ausbeute von 61-97% durch Kondensation von Ammoniak und Aminen mit den Enolethern 24a-f, die durch Umsetzung reaktiver Acylchloride 23 mit Ethylvinyl-ether dargestellt wurden. Die für hetero-Diels-Alder-Reaktionen benötigten N-Acyl-Derivate 19a-k und 21-t wurden durch Acylierung des Enamincarbaldehyds 1a und der Enamino-Ketone 2a-k gebildet.
    Notes: The synthesis of enaminecarbaldehydes 1a-s and 17a-c as well as enamino ketones 2a-k, and their N-acyl derivatives 19a-k and 21-t with electron accepting substituents at C-2 and at the CO group, respectively, is described. Condensation of methyl 2-formyl-3-oxopropanoate (13) with ammonia and the amines 14b-s gave the enaminecarbaldehydes 1a and 1b-s, respectively, in 72-93% yield. The enaminecarbaldehydes 17 were obtained by formylation of 15 with acetic formic anhydride. The synthesis of the enamino ketones 2a-k was accomplished in 61-97% yield by reaction of ammonia and amines with the enol ethers 24a-f, which were formed by treatment of reactive acyl chlorides 23 with ethyl vinyl ether. The enaminecarbaldehyde 1a as well as the enamino ketones 2a-k could be acylated to give 19a-k and 2l-t, respectively, which can be used in the hetero Diels-Alder reaction.
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  • 65
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 119-122 
    ISSN: 0009-2940
    Keywords: Bis(phosphonium) salts ; Pyridylphosphonium salts, tri-n-butyl- and triphenyl- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry of Triphenyl-(or Tri-n-butyl-)pyridylphosphonium salts, 2. - 2,4-Pyridinediylbis(phosphonium) Salts2,4-Pyridinediylbis(phosphonium) salts 1 react with nucleophiles to give 4-substituted products 6-8. Under radical reaction conditions the 5-position in 1a is attacked to yield 9. sodium azide transforms 1a into 8. This salt is used as starting material for 11. The removal of the phosphonium groups in 1 and in the resulting products can be carried out selectively.
    Notes: 2,4-Pyridindiylbis(phosphoniumsalze) 1 lassen sich mit nucleophilen Reaktionspartnern in die 4-substituierten Produkte 6-8 überführen. Unter radikalischen Bedingungen wird selektiv die 5-Position in 1a unter Bildung von 9 angegriffen. Nach Umsetzung mit Natriumazid entsteht zunächst das Salz 8, das als Ausgangsverbindung für 11 dient. Die Substitution der Phosphoniumgruppen aus den Edukten 1 und Produkten kann selektiv durchgeführt werden.
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  • 66
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 145-149 
    ISSN: 0009-2940
    Keywords: Cycloalkenes, 1-methyl- ; Ozonolysis ; Peroxyhemiacetals, cyclic ; Rubber, natural ; Tetrahydrofurans, 2-hydroperoxy- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ozonolyses of 1-Methylcyclopentene, 1-Methylcyclobutene, 5-Hexen-2-one and Natural Rubber in the Presence of MethanolOzonolyses of 1-methylcyclopentene (8a) and of 1-methylcyclobutene (8b) in methanol proceeded in each case in the two possible directions. The resulting methoxyperoxides 13 and 14 afforded the corresponding peroxyhemiacetals 15 and 19 by intramolecular reactions of the OOH with the corresponding carbonyl groups. Ozonolysis of 1-methylcyclobutene (8b) additionally gave the corresponding ozonide 17b and 2-hydroperoxy-5-methoxy-2-methyl-as well as 5-hydroperoxy-2-methoxy-2-methyltetrahydrofuran (16b and 18b). The mode of formation of these hydroperoxy compounds has been elucidated by ozonolyses of 5-hexen-2-one (25) and of natural rubber (28) in the presence of methanol.
    Notes: Ozonolysen von 1-Methylcyclopenten (8a) und von 1-Methylcyclobuten (8b) in Methanol verliefen jeweils nach beiden möglichen Spaltungsrichtungen. Die dabei gebildeten Methoxyhydroperoxide 13 und 14 ergaben durch intramolekulare Reaktionen der OOH- mit den Carbonylgruppen die entsprechenden Peroxyhalbacetale 15 bzw. 19. Bei der Ozonolyse von 1-Methylcyclobuten (8b) wurden zusätzlich das entsprechende Ozonid 17b sowie 2-Hydroperoxy-5-methoxy-2-methyl- und 5-Hydroperoxy-2-methoxy-2-methyltetrahydrofuran (16b und 18b) gebildet. Die Bildungsweise dieser Hydroperoxy-Verbindungen wurde durch Ozonolysen von 5-Hexen-2-on (25) und von Naturkautschuk (28) im Beisein von Methanol aufgeklärt.
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  • 67
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 169-174 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of New 3-substituted PyrrolesThe synthesis of 3-alkyl- (4), 3-(ω-bromoalkyl)- (5), 3-iodo- (6), 3-formyl- (9a), 3-acetyl-1-(triisopropylsilyl)pyrrole (9b), of 2-[1-(triisopropylsilyl)-3-pyrrolyl]-2-propanol (7), 1-(triisopropylsilyl)-3-pyrrolecarboxylic acid (8), and 7-[1-(triisopropylsilyl)-3-pyrrolyl]heptanoic acid (10) as well as the desilylation of these products to the corresponding 3-substituted pyrroles 11 is described. Intermediates in these syntheses are 1-(triisopropylsilyl)pyrrole (1), 3-bromo- (2), and 3-lithio-1-(triisopropylsilyl)pyrrole (3).
    Notes: Die Synthese von 3-Alkyl- (4), 3-(ω-Bromalkyl)- (5), 3-Iod- (6), 3-Formyl- (9a) und 3-Acetyl-1-(triisopropylsilyl)pyrrol (9b), von 2-[1-(Triisopropylsilyl)-3-pyrrolyl]-2-propanol (7), 1-(Triisopropylsilyl)-3-pyrrolcarbonsäure (8) und 7-[1-(Triisopropylsilyl)-3-pyrrolyl]heptansäure (10) sowie die Desilylierung dieser Produkte zu den entsprechenden 3-substituierten Pyrrolen 11 wird beschrieben. Zwischenstufen der Darstellung sind 1-(Triisopropylsilyl)pyrrol (1), 3-Brom- (2) und 3-Lithio-1-(triisopropylsilyl)pyrrol (3).
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  • 68
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    Berichte der deutschen chemischen Gesellschaft 122 (1989) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 69
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 223-230 
    ISSN: 0009-2940
    Keywords: Gold(I) silyl complexes ; Transition-metal silyl complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition-Metal Silyl Complexes, 26. - Gold(I) Silyl ComplexesComplexes of type L-Au-SiR3 with L = PR′3 or PhNC and SiR3 = Si(aryl)3, Si(SiMe3)3, or SiPh2Me are prepared by reaction of L-Au-Cl with LiSiR3. Depending on L and R, their stability decreases, in the order R′3P-Au-Si(aryl)3 〉 R′3P-Au-Si(SiMe3)3 〉 R′3P-Au-SiPh2Me ≈ PhNC-Au-SiR3. Reaction of R′3P-Au-CH3 or R′3P-Au-OAc with HSiR3 does not yield silyl complexes. However, using chlorinated silanes like HSiR2Cl, CH3/Cl or OAc/Cl exchange takes place. The Mössbauer spectrum of MePh2P-Au-SiPh3 (6) and NMR- and IR-spectroscopic investigations show that silyl groups act as strong σ donors towards the gold atom. MePh2P-Au-SiPh3 (6) and MePh2P-Au-Si(SiMe3)3 (7) have been characterized by X-ray structure analyses [Au—Si 235.4(4) and 235.6(2) pm]. The Au-Si bond in MePh2P-Au-SiPh2Tol (5) is cleaved by X2 (X = Cl, Br, I), HCl or MeI, but not by H2O or MeOH.
    Notes: Komplexe des Typs L-Au-SiR3 mit L = PR′3 oder PhNC und SiR3 = Si(aryl)3, Si(SiMe3)3 oder SiPh2Me wurden durch Umsetzung von L-Au-Cl mit LiSiR3 dargestellt. Ihre Stabilität sinkt in Abhängigkeit von L und R in der Reihenfolge R′3P-Au-Si(aryl)3 〉 R′3P-Au-Si(SiMe3)3 〉 R′3P-Au-SiPh2Me ≈ PhNC-Au-SiR3. Umsetzung von R′3P-Au-CH3 oder R′3P-Au-OAc mit HSiR3 ergibt keine Silyl-Komplexe, bei Verwendung chlorierter Silane, HSi-R2Cl, findet lediglich CH3/Cl- bzw. OAc/Cl-Austausch statt. Das Mößbauer-Spektrum von MePh2P-Au-SiPh3 (6) sowie NMR- und IR-spektroskopische Untersuchungen zeigen, daß Silylreste als starke σ-Donor-Liganden gegenüber dem Goldatom wirken. MePh2P-Au-SiPh3 (6) und MePh2P-Au-Si(SiMe3)3 (7) wurden durch Röntgenstrukturanalysen charakterisiert [Au—Si 235.4(4) und 235.6(2) pm]. Die Au—Si-Bindung in MePh2P-Au-SiPh2 Tol (5) wird durch X2 (X = Cl, Br, I), HCl oder MeI, nicht aber durch H2O oder MeOH gespalten.
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  • 70
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 245-252 
    ISSN: 0009-2940
    Keywords: Germylenes ; Germanium nitrogen compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Germylenes with Azides: Iminogermanes, Azidogermanes, Tetrazagermoles and HexaazadigermadispirododecanesGermylenes, X2Ge, stabilized by steric blocking and/or incorporation into five-membered ring systems, react with azido compounds YN3 depending on the steric requirements of the substituents X and Y to give iminogermanes, X2Ge=NY (1, 2) azidogermanes X2Ge(N3)NY2 (6-8) tetrazagermoles, X2Ge(— NY — N =)2 (10-16), and hexaazadigermadispirododecanes, [(— NR — CH2 — CH2 — NR —)Ge(μ-NY -)]2 (17, 18). NMR (1H, 13C, 14N, 15N, and 29Si), MS data, and X-ray structure analyses of the compounds 8, 9, 16, and 18 are reported.
    Notes: Durch sterische Blockierung und/oder Einbau in fünfgliedrige Ringsysteme stabilisierte Germylene, X2Ge, reagieren mit Azidoverbindungen, YN3, in Abhängigkeit von der Raumerfüllung der Substituenten X und Y zu Iminogermanen X2 Ge=NY (1, 2), Azidogermanen, X2Ge(N3)NY2 (6′8), Tetrazagermolen, X2Ge-(-NY-N=)2 (10-16), bzw. Hexaazadigermadispirododecanen, [(—NR—CH2—CH2—NR— )Ge(μ-NY-)]2 (17, 18). NMR-(1H, 13C, 14N, 15N und 29Si), MS-Daten und Röntgenstrukturanalysen für die Verbindungen 8, 9, 16 und 18 sind angegeben.
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 271-277 
    ISSN: 0009-2940
    Keywords: Chalcogenogermanes, (trifluoromethyl)- ; Disilaselenanes ; Germachalcogenanes, bis(trifluoromethyl)- ; Germanes, (trifluoromethyl)- ; Germatranes, (trifluoromethyl)- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: (Trifluormethyl)germanes, III. - Preparation of New (Trifluormethyl)germanium Chalcogene CompoundsStarting with the dihalogenobis(trifluoromethyl)germanes (CF3)2-GeX2 (X = Cl, or I), halogen-chalcogen exchange leads to corresponding chalcogen derivatives of the general type [(CF3)2GeE]n (6, 7) (E = O, NH, S, or Se). The resulting compounds differ in their degree of polymerisation. [(CF3)2GeO]x and the corresponding sesquioxane [(CF3)GeO1, 5]x are highly polymeric, quite in contrast to the corresponding germathianes and -selenanes. The crystal structure of [(CF3)2GeO]x (6a) was determined by X-ray single crystal diffraction. The reaction of CF3GeCl3 with triethanolamine results in the formation of 1-(trifluoromethyl)germatrane (13). Disilaselenane (10) reacts at low temperatures with chloro-(trifluoromethyl)germanes (CF3)nGeCl4-n under retention of one Si—Se bond to give (CF3)nGe(SeSiH3)4-n (11) and H3SiCl. Compounds with n = 3 and 2 could be isolated. Exchange of iodine by ECF3 takes place with iodogermanes (CF3)nGeI4-n and Hg(ECF3)2 (E = S, Se) with formation of a complete series of (trifluoromethyl)(trifluoromethylchalcogeno)germanes (CF3)nGe-(ECF3)4-n (3, 5).
    Notes: Durch Halogen-Chalkogen-Austauschreaktionen an (CF3)2)GeX2 (X = Cl, I) wurden Bis(trifluormethyl)germachalkogenane [(CF3)2GeE]n (6, 7) E = O, NH, S, Se) von unterschiedlichem Oligomerisierungsgrad erhalten. Die Germoxane [(CF3)2GeO]x und (CF3GeO1,5)x sind im Gegensatz zu den homologen Germathianen und -selenanen polymer, wobei die Struktur von [(CF3)2GeO]x (6a) durch eine Kristallstrukturanalyse ermittelt wurde. Durch Umsetzung von CF3GeCl3 mit Triethanolamin wird 1-(Trifluormethyl)germatran (13) erhalten. Disilaselenan (10) reagiert bei tiefen Temperaturen mit den Chlor (trifluormethyl)-germanen (CF3)nGeCl4-n monofunktionell unter Erhalt einer Si—Se-Bindung zu (CF3)nGe(SeSiH3)4-n (11) und H3SiCl, von denen die Verbindungen mit n = 3 und 2 isoliert werden konnten. Reaktionen der Iodgermane (CF3)nGeI4-n(1) mit Hg(ECF3)2) (E = S, Se) führen unter Substitution des Iods gegen die ECF3-Gruppen zur vollständigen Reihe der (Trifluormethyl)(trifluormethylchalkogeno)germane (CF3)nGe(ECF3)4-n (3, 5).
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 291-292 
    ISSN: 0009-2940
    Keywords: (Phthalocyaninato)copper complex, substituted with crown ethers ; Alkali metal extraction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A soluble (phthalocyaninato)copper(II) complex containing eight symmetrical benzo-15-crown-5 substituents, namely {2,3,9,10,16,17,23,24-octakis[[benzo-15-crown-5)-4′ -yl]oxymethyl]phthalocyaninato}copper(II) (2) from 1,2-bis{[benzo-15-crown-5)-4′-yl]oxymethyl}-4,5-dibromobenzene (1) and CuCN in quinoline or pyridine was synthesized. The crown-ether groups in 2 were shown to prefer intramolecular complexation with alkali metal ions.
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 463-466 
    ISSN: 0009-2940
    Keywords: C—C Rotation ; Sterical hindrance by SF5 groups ; Rotational barriers ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sterical Hindrance of the C—C Rotation by two SF5 GroupsAddition of SF5Cl to SF5CH=CF2 gives products carrying two SF5 groups on one carbon atom. As a consequence, C—C single bond rotation is strongly hindered. The highest rotational barrier observed is 61.7 kJ mol-1, rotational isomers are hence detectable at room temperature.
    Notes: Die Addition von SF5Cl an SF5CH=CF2 ergibt Produkte, die zwei SF5-Gruppen an einem Kohlenstoff tragen. In diesen kommt es zu einer starken Hinderung der Rotation um die C—C-Einfachbindung. Die höchste Rotationsbarriere wird mit 61.7 kJ mol-1 gefunden, d. h. Rotationsisomere sind bei Raumtemperatur getrennt nachweisbar.
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 467-472 
    ISSN: 0009-2940
    Keywords: Tetracarbonylchromium complexes ; 1,2,3,6-Tetrahydro-1,2,3,6-diphosphadiborine derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis, Structure, and Reactions of 1,2,3,6-Tetrahydro-1,2,3,6-diphosphadiborine DerivativesThe 1,2,3,6-tetrahydro-1,2,3,6-diphosphadiborine derivatives 3a and 3b are obtained by cyclocondensation of 1,2-bis[chloro(dialkylamino)boryl]ethenes 2 and 1,2-dipotassium 1,2-di-tert-butyldiphosphanediide. As in the case of 2,5-dihydro-1H-1,2,5-phosphadiborole derivatives 1 the temperature-dependent 1H-NMR spectra of 3b exhibit a lowered barrier of inversion at phosphorus. The X-ray structure analysis of 3b shows, that the six-membered C2B2P2 ring is nonplanar and the P atoms are coordinated pyramidally. Attempts to substitute the dialkylamino groups at the boron atoms of 3a and 3b with HCl·Et2O or tBuLi lead to cleavage of the B—P bonds. Reaction between 3a or 3b and Cr(CO)3(MeCN)3 does not result in the formation of tricarbonylchromium complexes but of tetracarbonylchromium complexes 6a and 6b with pentahapto-bonded ligands 3a and 3b.
    Notes: Die 1,2,3,6-Tetrahydro-1,2,3,6-diphosphadiborin-Derivate 3a und 3b entstehen durch Cyclokondensation aus 1,2-Bis[chlor(dialkylamino)boryl]ethenen 2 und 1,2-Dikalium-1,2-di-tert-butyldiphosphandiid. Die Temperaturabhängigkeit der 1H-NMR-Spektren von 3b dokumentiert wie bei 2,5-Dihydro-1H-1,2,5-phosphadiborol-Derivaten 1 eine erniedrigte Phosphor-Inversionsbarriere. Die Röntgenstrukturanalyse von 3b zeigt, daß der C2B2P2-Sechsring im Kristall nicht eben ist und daß die P-Atome pyramidal koordiniert sind. Versuche zur Substitution der Dialkylaminogruppen an den Boratomen von 3a und 3b mit HCl·Et2O oder tBuLi führen zur Spaltung der B—P-Bindungen. Die Umsetzung von 3a bzw. 3b mit Cr(CO)3(MeCN)3 ergibt keine Tricarbonylchrom-Komplexe, sondern die Tetracarbonylchrom-Komplexe 6a bzw. 6b, in denen die Liganden 3a und 3b pentahapto gebunden sind.
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  • 75
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organic Synthesis via Transition Metal Complexes, 34. - Novel Formation of C=C Bonds by Condensation of Acid Amides with Carbene Complexes Involving an Insertion of C2 Units into M=C BondsCarben complexes LnM=C(OEt)C6H5 1 [LnM = Cr(CO)5, Mo(CO)5, W(CO)5] and acid amides RCH2CONMe2 2 undergo a novel condensation reaction in presence of POCl3/Et3N to give alkenyl aminocarbene complexes 3. The reaction involves an insertion of a C2 unit of 2 into the M=C bond of 1 to give a C=C bond. It can be achieved with open-chain and cyclic amides like N-methyl-2-pyrrolidone (8). the structures of the complexes have been determined spectroscopically. A mechanism of the reaction is suggested.
    Notes: Carbenkomplexe LnM=C(OEt)C6H5 1 [LnM = Cr(CO)5, Mo(CO)5, W(CO)5] lassen sich mit Säureamiden RCH2CONMe2 2 und POCl3/Et3N zu Alkenyl-Aminocarben-Komplexen 3 kondensieren. Dabei wird eine C2-Einheit von 2 in die M=C-Bindung von 1 eingeschoben und eine C=C-Bindung neu geknüpft. Die Reaktion gelingt mit offenkettigen und cyclischen Amiden wie N-Methyl-2-pyrrolidon (8). Die Strukturen der Komplexe wurden spektroskopisch ermittelt und Vorschläge zur Deutung des Reaktionsablaufs gemacht.
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  • 76
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 711-714 
    ISSN: 0009-2940
    Keywords: Azulenes ; 1,6-Methano[10]annulenes ; 1,2,4,5-Tetrazine ; [4 + 2] Cycloadditions, „inverse“ ; Pyridazines, annulated ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Azulene and 1,6-Methano[10]annulene as Dienophiles in the Diels-Alder Reaction with 3,6-Bis(trifluoromethyl)-1,2,4,5-tetrazineThe LUMO-diene-controlled [4 + 2] cycloadditions of azulene (2) and 1,6-methano[10]annulene (14) with the electron-deficient s-cisfixed diazadiene system of 3,6-bis(trifluoromethyl)-1,2,4,5-tetrazine (1) are described. Contrary to expectation, 1 reacts under unusually mild conditions with 2 (or its valence tautomer 3) to yield the adduct 4 which after N2 elimination rearranges to the benzo[f]phthalazine 11. The Diels-Alder reaction of 1 with 14 (or its valence tautomer 13) leads to the annulated dihydropyridazines 15 and 16, which can be dehydrogenated by silver(I) oxide to the methano-bridged aromatic cyclodecapyridazine 17 and the olefinic phthalazino[5,6-f]phthalazine 18, respectively. Besides, the methano-bridged cyclodeca[d]pyridazine 24 is prepared.
    Notes: LUMO-Dien-kontrollierte [4 + 2]-Cycloadditionen von Azulen (2) und 1,6-Methano[10]annulen (14) an das elektronenarme, s-cis-fixierte Diazadiensystem von 3,6-Bis(trifluoromethyl)-1,2,4,5-tetrazin (1) werden beschrieben. Wider Erwarten reagiert 1 unter ungewöhnlich milden Bedingungen mit 2 (oder dessen Valenztautomerem 3) zum Addukt 4, das nach N2-Eliminierung und nachfolgender Umlagerung das Benzo[f]phthalazin 11 liefert. Die Diels-Alder-Reaktion von 1 mit 14 (oder dessen Valenztautomer 13) führt zu den beiden anellierten Dihydropyridazinen 15 und 16, die mit Silber(I)-oxid zu dem Methano-überbrückten aromatischen Cyclodecapyridazin 17 bzw. dem olefinischen Phthalazino[5,6-f]phthalazin 18 dehydriert werden können. Daneben wird das Methano-überbrückte Cyclodeca[d]pyridazin 24 dargestellt.
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  • 77
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 715-719 
    ISSN: 0009-2940
    Keywords: Alkyne ; Carbene ; Cycloisomerization ; Pyrolysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Über die thermische Cycloisomerisierung langkettiger Alkylacetylene in der GasphaseDie thermische Cycloisomerisierung einiger Alkylacetylene wurde in einem Laborrohrreaktor aus Quarzglas untersucht. 1-Hexin (1) wird dabei durch 1,2-H-Verschiebung und 1,5-C,H-Insertion des intermediär gebildeten Pentylidencarbens (vgl. Schema 1) in 3-Methyl-1-cyclopenten (5) umgelagert. 5-Methyl-1-hexin (2) reagiert analog; es entsteht 3,3-Dimethyl-1-cyclopenten (6). Im Gegensatz zur Bildung von in 3-Stellung methylierten Cyclopentenen aus 1-Alkinen ensteht aus 2-Hexin (3) 1-Methyl-1-cyclopenten (7). Offenbar ist die Acetylen-Vinyliden-Umlagerung nicht auf 1,2-H-Verschiebung beschränkt. Der Mechanismus der Cycloisomerisierung von Alkylacetylenen wird durch Untersuchungen mit D-markierten Alkinen bestätigt. Die Ergebnisse lassen den Schluß zu, daß die Cycloisomerisierung ohne weiteres mit dem überwiegend nach einem Radikalketten-Mechanismus verlaufenden thermischen Zerfall konkurrieren kann.
    Notes: The thermal cycloisomerization of some alkylacetylenes was investigated in a tubular quartz reactor. At 570°C 1-hexyne (1) rearranges to 3-methyl-1-cyclopentene (5) with a selectivity of about 27 by a reaction sequence including an acetylene-vinylidene rearrangement and 1,5-C,H insertion of the intermediately formed alkylidenecarbene species. 5-methyl-1-hexyne (2) behaves analogously forming 3,3-dimethyl-1-cyclopentene (6), while 2-hexyne (3) provides 1-methyl-1-cyclopentene (7) indicating that the acetylene-vinylidene rearrangement is obviously not restricted to 1,2-H shifts. The mechanism of the cycloisomerization of alkylacetylenes is investigated by means of D-labeled parent alkynes. The results show that the unimolecular cycloisomerization via alkylidenecarbenes obviously can be an important channel despite the dominance of a radical chain course.
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  • 78
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 745-748 
    ISSN: 0009-2940
    Keywords: Flash Pyrolysis ; Matrix IR spectroscopy ; Photolysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Methoxy- und AminoisocyanatMethoxyisocyanat (1) kann durch Photolyse von Azidoameisensäure-methylester (3) oder Pyrolyse von N-Methoxycarbonyl-O-methylhydroxylamin (4) dargestellt werden. Aminoisocyanat (2) ist auf ähnliche Weise durch Photolyse von Carbamoylazid (12) und Pyrolyse von Carbazinsäure-methylester (13) oder 3,4-Diaminofurazan (14) zugänglich. Die IR-Spektren von 1 und 2, aufgenommen in einer Argon-Matrix bei 10 K, werden diskutiert.
    Notes: Methoxyisocyanate (1) can be prepared by photolysis of methyl azidoformate (3) or pyrolysis of N-methoxycarbonyl-O-methyl-hydroxylamine (4). Aminoisocyanate (2) is similarly formed on photolysis of carbamoyl azide (12) and pyrolysis of either methyl carbazate (13) or 3,4-diaminofurazan (14). The infrared spectra of 1 and 2 in an argon matrix at 10 K have been measured, and some of their properties are discussed.
    Additional Material: 1 Ill.
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  • 79
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 749-752 
    ISSN: 0009-2940
    Keywords: Matrix isolation ; Photochemistry ; Theoretical vibrational spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Infrarot-Spektren und Photochemie von Isodiazen und seinen deuterierten IsotopomerenDie Matrixisolation von Aminoisocyanat eröffnet einen neuen ergiebigen Weg zur Darstellung von Isodiazen (Aminonitren). Damit ist es möglich geworden, nicht nur sein IR-Spektrum eindeutig festzulegen und mit Hilfe von ab-initio-Rechnungen zu interpretieren, sondern auch seine Photochemie zu untersuchen.
    Notes: The matrix isolation of aminoisocyanate opens a new efficient route for the preparation of isodiazene (aminonitrene). Its infrared spectrum can now, with the help of ab initio calculations, be interpreted, and its photochemistry can be studied.
    Additional Material: 2 Ill.
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  • 80
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 795-796 
    ISSN: 0009-2940
    Keywords: Thiochalcones ; Thienylchalcones ; Fries rearrangement ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four new thienylchalcones (1, 4, 5, and 6) were synthesized by condensing hydroxy-nitroacetophenones with 2-thiophene and 3-thiophenecarboxaldehydes in the presence of dilute NaOH.
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  • 81
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 767-779 
    ISSN: 0009-2940
    Keywords: Molecular twisting ; cis-9,10-Dihydronaphthalenes, persubstituted ; Valence isomerizations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Valence Isomerizations, 17. - Persubstituted cis-9,10-Dihydronaphthalenes and their Valence IsomerizationsThe tricyclic diester 10 is available from 2-butyne in a six-step synthesis with an overall yield of 10%. Thermolysis of 10 gives the bicyclic diester 11 which upon UV irradiation yields 12 as the first persubstituted cis-9,10-dihydronaphthalene. X-ray analysis of 12 shows the molecule considerably twisted along the central bond. In addition, the planes of the ester groups are at an angle of approximately 60° to the „planes“ of the six-membered rings so that conjugation of the diene systems with the carbonyl functions is virtually interrupted, an effect which is reflected by the unusual spectroscopic properties of 12. The same structural features can be found in decamethyl-cis-9,10-dihydronaphthalene (16). When heated slightly, 12 is converted to the tetracyclic valence isomer 34. On reduction of 12 with diisobutylaluminum hydride both, dihydronaphthalene dicarbinol 25 as well as its unexpected positional isomer 26, are formed depending on the reaction conditions. Etherification of the reduction products with CH2N2/Et2O—BF3 furnishes a mixture of the three isomeric bis(methoxymethyl) compounds 31, 32 and 33. They can be separated by chromatography in the cold, but revert to the mixture of the three isomers at room temperature. We consider diradical 38 to be the intermediate of this intriguing valence isomerization.
    Notes: Der tricyclische Diester 10 ist in sechs Stufen in einer Gesamtausbeute von 10% aus 2-Butin zugänglich. Thermolyse von 10 liefert den Bicyclus 11, bei dessen UV-Bestrahlung das erste persubstituierte cis-9,10-Dihydronaphtalin 12 gebildet wird. Eine Röntgenstrukturanalyse von 12 beweist die starke Verdrillung des Moleküls um die zentrale Bindung. Die Ebenen der Ester-Gruppen stehen ungefähr in einem 60°-Winkel zu den Sechsring-„Ebenen“, so daß die Konjugation der Dien-Systeme mit den Carbonyl-Funktionen praktisch unterbrochen ist, ein Effekt, der sich in den ungewöhnlichen spektroskopischen Eigenschaften von 12 widerspiegelt. Analoge Strukturmerkmale gelten auch für das Decamethyl-cis-9,10-dihydronaphthalin (16). Bicyclus 12 wandelt sich bei leichtem Erwärmen in den valenzisomeren Tetracyclus 34 um. Reduktion von 12 mit Diisobutylaluminiumhydrid gibt je nach den Reaktionsbedingungen das Dihydronaphthalindicarbinol 25 bzw. das unerwartete Stellungsisomere 26. Veretherung der Reduktionsprodukte mit CH2N2/Et2O—BF3 liefert ein Gemisch der drei isomeren Bis(methoxymethyl)-Verbindungen 31, 32 und 33, die chromatographisch in der Kälte trennbar sind, aber schon bei Raumtemperatur wieder das Gemisch der drei Isomeren zurückbilden, wobei das Diradikal 38 als Zwischenprodukt dieser erstaunlichen Valenzisomerisierung anzunehmen ist.
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  • 82
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 803-808 
    ISSN: 0009-2940
    Keywords: Bismuth organic compounds ; Fluorinated aromatic rings ; Square pyramidal bismuth ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Structures of Pentaarylbismuth CompoundsPentaarylbismuth compounds were synthesized by the known reaction Ar3BiX2 + 2 Ar′Li → 2 LiX + BiAr3Ar′2. Whenever possible they were characterized by single-crystal X-ray structure determination. In two cases almost ideal square-pyramidal geometry was found, in a third case there were two different molecules in the unit cell, both again with square-pyramidal geometry. None of these novel bismuth pentaaryls exhibit the deep coloration and the dichroism of Bi(C6H5)5.
    Notes: Pentaarylbismut- Verbindungen wurden durch die bekannte Reaktion BiAr3X2 + 2 Ar′Li → 2 LiX + BiAr3Ar′2 hergestellt und, soweit möglich, durch Röntgenbeugung an Einkristallen strukturell untersucht. In zwei Fällen erwies sich die Struktur als nahezu ideal quadratisch-pyramidal, in einem dritten Fall wurden zwei unterschiedliche Moleküle im Kristall gefunden, die aber beide wiederum quadratisch-pyramidal sind. Keines der hier vorgestellten neuen Bismutpentaaryle zeigt die tiefe Färbung und den Dichroismus von Bi(C6H5)5.
    Additional Material: 5 Ill.
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  • 83
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 533-535 
    ISSN: 0009-2940
    Keywords: Free radicals ; Triphenylmethyl radicals ; ESR measurements ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sterically Hindered Free Radicals, XIX. - Stable 4,4′,4″-Trisubstituted Triphenylmethyl RadicalsThe title radicals (4-R—C6H4)3C. (1), R = F, Cl, Ph, OMe, NO2, tBu, OEt, SMe, CN, CF3, have been prepared, the latter four for the first time, and the ESR spectra have been recorded. aoH, amH, and apR are listed. The intensities of the ESR signals remain constant within the accessible range of -30 to + 100°C. Within this range these radicals are kinetically stable and do not dimerize like other trityls by, e.g., α,p-, α,o-, α,α -recombinations.
    Notes: Die Titelradikale (4-R—C6H4)3C· (1), R = F, Cl, Ph, OMe, NO2, tBu, OEt, SMe, CN, CF3, wurden dargestellt, davon die vier letzten erstmalig, und mittels ESR-Spektroskopie vermessen. aoH, amH und apR werden angegeben. Die ESR-Signale bleiben im gesamten zugänglichen Temperaturbereich - 30 bis + 100°C in ihrer Intensität unverändert. Daraus folgt, daß alle diese Radikale im genannten Temperaturbereich kinetisch stabil sind, also nicht wie andere Trityle zu Dimerisierungen, etwa α,p-, α,o-, α,α-, neigen.
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  • 84
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 523-531 
    ISSN: 0009-2940
    Keywords: Dicyclopenta-s-indacene ; 2-Osxa[3.3.3]propellane derivatives ; Pentalene derivatives ; [3.3.3]Propellane-3,7-dione ; Weiss reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Novel Products in the Weiss Reaction of 1,2-Cyclopentanedione. Improved Preparation of [3.3.3]Propellane-3,7-dioneThe reaction of 1,2-cyclopentanedione (1c, 9) with the 3-oxoglutarate 4 in methanol/water in the presence of sodium bicarbonate followed by hydrolysis and decarboxylation of the product mixture affords the oxa[3.3.3]propellane ester 11c in addition to the [3.3.3]propellanedione 6c. The alkali enolates of 4 react with 9 in boiling methanol to yield the yellow, poorly soluble alkali dihydropentalenolates 12M and the [3.3.3]propellane tetraester 5c, which on hydrolysis and decarboxylation yields 53% of 6c. The dihydropentalenol 12H equilibrates with the tautomeric β-oxodiester 13, the proportion of which increases with solvent polarity. In methanol solutions, 12H and 13 add diastereoselectively forming the dicyclopenta-s-indacene tetraester syn-14, which is derived from a novel pentacyclic ring system. The configuration of syn-14 is determined by X-ray diffraction analysis. The mechanisms of formation are discussed for 11c, 12M, and syn-14.
    Notes: Nach Umsetzung von 1,2-Cyclopentandion (1c, 9) mit dem 3-Oxoglutarsäureester 4 in Methanol/Wasser in Gegenwart von Natriumhydrogencarbonat, saurer Hydrolyse und Decarboxylierung des Produktgemischs erhält man neben dem [3.3.3]Propellandion 6c den Oxa[3.3.3]propellanester 11c. Die Alkali-Enolate von 4 reagieren mit 9 in siedendem Methanol zu den gelben, schwer löslichen Dihydropentalenolaten 12M und dem [3.3.3]Propellantetraester 5c, der nach Hydrolyse und Decarboxylierung 53% 6c ergibt. Das Dihydropentalenol 12H liegt im Gleichgewicht mit dem tautomeren β-Oxodiester 13 vor, dessen Anteil mit der Polarität des Lösungsmittels zunimmt. In Methanol addieren sich 12H und 13 diastereoselektiv und bilden den Dicyclopenta-s-indacentetraester syn-14, der sich von einem neuartigen, pentacyclischen Ringsystem ableitet. Die Konfiguration von syn-14 wird durch Röntgenstrukturbestimmung aufgeklärt. Die Mechanismen der Bildung von 11c, 12M und syn-14 werden diskutiert.
    Additional Material: 2 Ill.
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  • 85
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 553-559 
    ISSN: 0009-2940
    Keywords: Amino acids ; Diastereoselective addition ; 1-(Methacryloyl)proline derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Amino Acids, 15. - Diastereoselective Addition of Thiocarboxylic Acids to 1-(Methacryloyl)proline and-prolinol DerivativesThiocarboxylic acids 6 add to 1-(methacryloyl)-substituted proline and prolinol derivatives stereoselectively to give the 1-[3-(acylthio)-2-methylpropionyl]proline and -prolinol derivatives 7,7′ and 9. The less soluble (2S,2′R)-diastereomers are obtained in optical yields ≥ 98% by digestion of the crude products, the configuration of which was determined by acid hydrolysis of (2S,2′R)-7,7′ to (R)-3-mercapto-2-methylpropionic acid [(R)-8]. The stereoselectivity of the additions may be explained by a sevenmembered ring intermediate with an intramolecular H bridge, to which the S-nucleophiles add preferentially to give the compounds with the (2′R)-configuration.
    Notes: Thiocarbonsäuren 6 addieren stereoselektiv mit hohen optischen Ausbeuten an 1-(Methacryloyl)-substituierte Prolin- und Prolinol-Derivate zu den 1-[3-(Acylthio)-2-methylpropionyl]prolin-und -prolinol-Derivaten 7,7′ und 9. Durch Digerieren der Rohprodukte mit Diethylether werden die schwerer löslichen (2S,2′R)-Diastereomeren in optischen Ausbeuten ≥98% erhalten, deren Konfiguration durch Acidolyse von (2S,2′R)-7,7′ zu (R)-3-Mercapto-2-methylpropansäure [(R)-8] bewiesen wurde. Die Stereoselektivität der Additionen wird über einen Siebenring mit intramolekularer H-Brücke als Zwischenstufe, an die Schwefelnucleophile bevorzugt unter Bildung der (2′R)-Konfiguration addieren, gedeutet.
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  • 86
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 545-551 
    ISSN: 0009-2940
    Keywords: Amino acids ; Diastereoselective addition ; 1-Acryloylproline esters ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Amino Acids, 14. - Diastereoselective Addition of Benzenesulfenyl Chloride to 1-Acryloylproline Esters(S)-Proline esters (S)-1 react with acryloyl chloride (2) to give 1-acryloylproline esters (S)-3 in good yields. Addition of benzenesulfenyl chloride (6) to (S)-3 at -95°C in dichloromethane results in 1-[2-chloro-3-(phenylthio)propionyl]proline esters (2S,2′R/2S,2′S)-7. The diastereoselectivity of the addition depends on the conformer ratio 3′/3″ of the starting material (S)-3. The diastereomers are separated by MPLC. Configuration at C-2′ of the resulting main products (2S,2′S)-7 was proved by independent synthesis. The diastereoselectivity of the addition of 6 to (S)-3 is interpreted to result from formation of a complex of the benzenesulfenyl cation with the proline ester group and subsequent electrophilic addition to a thiiranium intermediate B with (2S,2′R) configuration; the (2S,2′S) diastereomeric adduct 7 then results by nucleophilic attack of chloride at C-2′ under ring opening.
    Notes: Die 1-Acryloylprolinester (S)-3 werden durch N-Acylierung der Prolinester (S)-1 mit Acryloylchlorid (2) in guten Ausbeuten hergestellt; sie addieren Benzolsulfenylchlorid (6) bei -95°C in Dichlormethan mit hoher Diastereoselektivität zu 1-[2-Chlor-3-(phenylthio)propionyl]prolinestern (2S,2′R/2S,2′S)-7, die mittels MPLC getrennt werden. Die Diastereoselektivität der Addition hängt vom Konformerenverhältnis 3′/3″ der Edukte (S)-3 ab. Der Beweis der Konfiguration an C-2′ der als Hauptprodukte anfallenden Diastereomeren (2S,2′S)-7 wird durch eine unabhängige Synthese erbracht. Die Diastereoselektivität der Addition von 6 an (S)-3 wird über eine Komplexbildung des Phenylsulfenylkations mit der Prolinestergruppe und eine sich anschließende elektrophile Reaktion zu einer Thiiranium-Zwischenstufe B mit (2S,2-R)-Konfiguration gedeutet; das (2S,2′S)-diastereomere Additionsprodukt 7 entsteht dann durch nucleophilen Angriff des Chlorids an C-2′ unter Ringöffnung.
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  • 87
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    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 851-855 
    ISSN: 0009-2940
    Keywords: Diphosphines ; Tungsten - tungsten quadruple bond ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese und Struktur von W2Cl4{μ(iPr2PCH2CH2CH2PiPr2)}2: Eine durch sperrige, chelatisierende Diphosphane überbrückte Wolfram - Wolfram-VierfachbindungDie Reduktion von WCl4 in THF durch zwei Äquivalente Na/Hg in Gegenwart des sperrigen, chelatisierenden Diphosphinopropans iPr2PCH2CH2CH2PiPr2 (dippp) liefert den violetten, zweikernigen Komplex W2Cl4(μ-dippp)2. Der Komplex besitzt eine W-W-Vierfachbindung und β-Struktur, d.h. die chelatisierenden Diphosphinopropan-Liganden verbrücken die beiden Metall-Zentren. Die 1H-NMR-spektroskopischen Daten zeigen Tieffeldverschiebungen für die dippp-Liganden, die im Einklang mit der β-Struktur stehen. Das 31P{1H}-NMR-Spektrum besteht aus einem Singulett mit 183W-Satelliten. Die Röntgen-Stukturanalyse ergibt für die β-Struktur einen Torsionswinkel P-W-W-P von 75.9° und eine W-W-Bindungslänge von 2.297(1) Å. Aus den Molekülstruktur-Daten und den 1H-NMR-Tieffeldverschiebungen kann die diamagnetische Anisotropie χ der W-W-Vierfachbindung mit - 3000 ± 300 × 10-36 m3/Molekül abgeschätzt werden. Die für den festen Zustand beobachtete Chiralität wird auch in Lösung beibehalten.
    Notes: The reduction of WCl4 in THF by two equivalents of Na/Hg in the presence of the bulky chelating diphosphine iPr2PCH2-CH2CH2PiPr2 (dippp) generates the purple, binuclear complex W2Cl4(μ-dippp)2. The quadruply-bonded molecule has a β structure, that is, the chelating diphosphine bridges the two metal centers. 1H-NMR spectral data show downfield shifts for the ligand protons consistent with the β structure. The 31P{1H}-NMR spectrum consists of a singlet with 183W satellites. The X-ray crystal structure has a twist angle (P-W-W-P torsion angle) of 75.9°, and the W-W bond length is 2.297(1) Å. Using the solidstate data and the observed downfield shifts in the 1H-NMR spectrum, the diamagnetic anisotropy χ has been estimated as - 3000 ± 300 × 10-36 m3/molecule. The chiral structure observed in the solid phase is retained in solution.
    Additional Material: 4 Ill.
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  • 88
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 861-864 
    ISSN: 0009-2940
    Keywords: Aminoiminophosphanes ; 1,3,2λ5,4-Thiazaphosphaboretidines ; 1,2,4,3,5-Trithiadiborolanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Characterization of 1, 3, 2λ5, 4-ThiazaphosphaboretidinesThe reaction of 1,2,4,3,5-trithiadiborolanes with silylated aminoiminophosphanes leads to the 1,3,2λ5,4-thiazaphosphaboretidines 1a-i. The formation of 1h, i is accompanied by an exchange of the substituents bonded to the N atoms. 1H-, 11B-, 13C-, 29Si-, 31P-NMR, and mass spectra are discussed.
    Notes: Die Umsetzung von 1,2,4,3,5-Trithiadiborolanen mit silylierten Aminoiminophosphanen führt zu den 1,3,2λ5,4-Thiazaphosphaboretidinen 1a-i. Die Bildung von 1h, i wird von einem Austausch der N-ständigen Substituenten begleitet. 1H-, 11B-, 13C-, 29Si-, 31P-NMR- und Massenspektren werden diskutiert.
    Additional Material: 3 Tab.
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  • 89
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 857-860 
    ISSN: 0009-2940
    Keywords: Alkenylboranes ; Alkenylstannanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Convenient Route from Alkenylboranes to AlkenylstannanesAlkenyldialkylboranes 1 with various substituents at the C=C double bond, including organometallic groups such as the trimethylstannyl or trimethylsilyl group, react in hexane solution with (diethylamino)- or (dimethylamino)trimethylstannane (2) in the presence of a catalytic amount of lithium dimethyl- or diethylamide (3) to give aminodialkylboranes 4 and alkenyltrimethylstannanes 5 in high yields with retention of the configuration at the C—C double bond. With (diethylamino)trimethylplumbane (2c) the less stable alkenes 5Pb are obtained. A mechanism is proposed, and 1H-, 13C-, 29Si-, 119Sn- und 207Pb-NMR-data are reported.
    Notes: Alkenyldialkylborane 1 mit verschiedenen Substituenten an der C=C-Doppelbindung, einschließlich organometallischer Gruppen wie dem Trimethylstannyl- oder dem Trimethylsilyl-Rest, reagieren in Hexan mit (Diethylamino)- oder (Dimethylamino)trimethylstannan (2) in Gegenwart einer katalytischen Menge von Lithium-diethylamid (3b) oder -dimethylamid (3a) in hoher Ausbeute unter Beibehaltung der Konfiguration an der C—C-Doppelbindung zu den entsprechenden Alkenylstannanen 5 und Aminoboranen 4. Durch Einsatz von (Diethylamino)trimethylplumban (2c) lassen sich die weniger stabilen Alkene 5Pb erhalten. Ein Mechanismus wird vorgeschlagen, und 1H-, 13C-, 29Si-, 119Sn- und 207Pb-NMR-Daten werden mitgeteilt.
    Additional Material: 1 Tab.
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  • 90
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1919-1924 
    ISSN: 0009-2940
    Keywords: Hydrogen transfer ; Ziegler catalysis ; Dihydroarenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ziegler Nickel Catalysts for Hydrogen Transfer ReactionsCatalysts prepared from Ni(acac)2 and AlEt3 show high catalytic activity in the hydrogen transfer between dihydroarenes, but hardly any isomerisation and H/D scrambling is observed. The active form of the catalyst is produced only in the presence of the starting material. Kinetic experiments, especially those concerning the introduction periods and the inhibition, are indicative of a complex reaction mechanism. The first hydrogen is preferentially abstracted from the 2-position, the second with complete cis selectivity.
    Notes: Der aus Ni(acac)2 und AlEt3 dargestellte Katalysator zeigt eine hohe Aktivität beim H-Transfer zwischen Dihydroarenen, neben dem Isomerisierungen und H/D-Austausch kaum ablaufen. Die aktive Form entsteht erst in Gegenwart des Edukts. Kinetische Untersuchungen, vor allem zur Induktionsperiode und zur Hemmung, deuten auf einen komplexen Ablauf. Der Wasserstoff wird cis-selektiv abgespalten, primär bevorzugt aus der 2-Position.
    Additional Material: 1 Ill.
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  • 91
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1925-1927 
    ISSN: 0009-2940
    Keywords: Hydrogen transfer ; Olefin isomerization ; Cobalt complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hydrogen Transfer Reactions, 13.  -  Catalysis of Disproportionation by (Dinitrogen)hydridotris(triphenylphosphine)cobalt(I)For both C—H activation and olefin isomerization, CoH(N2)(PPh3)3 (1) is a more powerful catalyst than the Wilkinson complex. In 1,2-dihydronaphthalene (2), a two-step cis abstraction of the hydrogen atoms is found with small regioselectivity in the first step.
    Notes: Die Aktivität des Komplexes CoH(N2)(PPh3)3 (1) liegt bei der C—H-Aktivierung deutlich höher als beim Wilkinson-Katalysator. Noch effektiver wird aber eine Olefin-Isomerisierung induziert. Die zweistufige H-Abstraktion erfolgt beim 1,2-Dihydronaphthalin (2) cis-selektiv, der Primärschritt aber kaum regioselektiv.
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  • 92
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1935-1938 
    ISSN: 0009-2940
    Keywords: as-Triazinium salt, fused ; Ring transformation ; Solvatochromy, negative ; Zwitterion ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese und Ringtransformation von neuen kondensierten as-Triazinium-SalzenDie Reaktion des 1,2-Diaminopyridinium-Salzes 1 mit dem Furandion 2 ergab ein Pyrido-as-triazinon 3, das zum tricyclischen Furo[2,3-e]pyrido[1,2-b]-as-triazinium-Salz 5 cyclisiert wurde. Die Reaktion von 5 mit Nucleophilen führte zu unterschiedlichen Produkten: mit wäßriger Base entstand das bicyclische Triazinon 4, mit dem Methoxid-Ion und sekundären Aminen wurden die stabilen Zwitter-Ionen 7a, b erhalten, wohingegen Ammoniak und Hydrazine unter Transformation des Furanringes die neuen tricyclischen kondensierten Pyrrole 10, 11 bzw. Pyridazine 13, 14a, b ergaben.
    Notes: The 1,2-Diaminopyridinium salt 1 was treated with furandione 2 to give pyrido-as-triazinone 3, which could be cyclized to the tricyclic furo[2,3-e]pyrido[1,2,-b]-as-triazinium salt 5. Reaction of 5 with nucleophiles resulted in different types of products. Thus, aqueous base afforded bicyclic triazinone 4, methoxide ion or secondary amine led to stable zwitterions 7a, b, whereas ammonia and hydrazines resulted in ring transformation of the furan moiety, and gave new fused tricyclic pyrroles (10, 11) and pyridazines (13, 14), respectively.
    Additional Material: 1 Ill.
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  • 93
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1947-1953 
    ISSN: 0009-2940
    Keywords: Enol ethers ; [n](2,4)Phloroglucinophanes ; Autoxidation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations of the Autoxidation and the Rearrangement of [n](2,4)PhloroglucinophanesIn the autoxidation of [n](2,4)phloroglucinophanes 3 hydroperoxides 7 are isolated in several cases as the first oxidation products; they react to the more stable monohydroxylated compounds 8 with different rates. Acylphloroglucinophanes 5, however, react with oxygen to give the dihydroxylated compounds 9. The autoxidation rate of the phloroglucinophanes 3, 5 is markedly larger than that of diethylphloroglucinols 6. In alkaline solution the hydroxy compounds 8 rearrange to the dihydroxycyclopentenones 12; the rate of rearrangement correlates with the decrease of ring strain.
    Notes: Bei der Autoxidation von [n](2,4)Pholoroglucinophanen 3 können in einigen Fällen Hydroperoxide 7 als erste Oxidationsprodukte isoliert werden, die unterschiedlich rasch in die stabileren monohydroxylierten Verbindungen 8 übergehen. Aclphloroglucinophane 5 reagieren mit Luftsauerstoff dagegen zu den zweifach hydroxylierten Verbindungen 9. Die Geschwindigkeit der Autoxidation ist bei den Phloroglucinophanen 3, 5 deutlich größer als bei den 2,4-Diethylphloroglucinen 6. Im alkalischen Medium lagern sich die Hydroxyverbindungen 8 in die Dihydroxycyclopentenone 12 um, wobei für die Geschwindigkeit der Umlagerung eine Korrelation mit der Abnahme an Ringspannung gefunden wird.
    Additional Material: 3 Tab.
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  • 94
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1963-1967 
    ISSN: 0009-2940
    Keywords: Allenyl azides, ring closure of ; Propargyl azides, rearrangement, base-induced ; Triazafulvenes, nucleophilic addition to ; 1,2,3-Triazoles, preparation of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Unsaturated Azides, 7.  -  Base-catalyzed Formation of Allenyl Azides from Propargyl Azides: New Syntheses for 1,2,3-TriazolesThe propargyl azides 10, 14, 17, 20, and 28 undergo a base-catalyzed (prototropic) rearrangement to short-lived allenyl azides. These intermediates rapidly cyclize to triazafulvenes, which can be trapped by nucleophiles (methanol, sodium hydroxide, ammonia) to give 1,2,3-triazoles. Starting with the precursors 9, 13, 16, 19, and 27 one-pot syntheses lead to the heterocycles 12, 15, 18, 21, and 29. Depending on the reaction conditions, compound 10 regioselectively yields 12c (75%) by prototropic rearrangement (path B) or by migration of the azide group (path A) the isomer 11c (62%).
    Notes: Die Propargylazide 10, 14, 17, 20 und 28 lagern sich basenkatalysiert (prototrop) zu kurzlebigen Allenylaziden um. Diese Zwischenstufen cyclisieren rasch zu Triazafulvenen, die mit Nucleophilen (Methanol, Natriumhydroxid, Ammoniak) als 1,2,3-Triazole abgefangen werden können. Ausgehend von den Vorläufern 9, 13, 16, 19 und 27 führen Eintopf-Synthesen zu den Heterocyclen 12, 15, 18, 21 und 29. In Abhängigkeit von den Reaktionsbedingungen liefert 10 über die prototrope Umlagerung (Weg B) regioselektiv 12c (75%) oder durch Azidwanderung (Weg A) die isomere Verbindung 11c (62%).
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  • 95
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2023-2025 
    ISSN: 0009-2940
    Keywords: Homoallylic alcohols ; [2,3] Sigmatropic rearrangement ; Stereoselective synthesis of alcohols ; [2,3] Wittig rearrangement ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reductive cleavages of allyl [(phenylthio)methyl] ethers (8, 11) and an allyl [(tolylsulfonyl)methyl] ether (14) with lithium naphthalenide in THF furnish homoallylic alcohols (9, 12). The steric course of these transformations (E/Z selectivity in the case of 9, syn/anti selectivity for 12) is very similar to that of analogous Wittig-Still rearrangements.
    Additional Material: 1 Tab.
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  • 96
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 97
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2049-2054 
    ISSN: 0009-2940
    Keywords: Ligating properties ; Pentaphosphaferrocenes ; Sandwich and triple-decker complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pentaphospaferrocenes as Complex LigandsThe interaction of [Cp*Fe(P5)] (1a) with [Cr(CO)5(thf)] and [Cp(CO)2Mn(thf)], respectively, affords [Cp*Fe(P5){Cr(CO)5}2] (2) as well as [Cp*Fe(P5){Mn(CO)2Cp}n] (4a-d; n = 1-4; Cp* = η5-C5Me5). Irradiation of 1 and [CpFe(C6H6)]PF6 gives the cationic 30-VE triple-decker complexes [CpFe(μ, η5-P5)Fe(C5Me4R)]PF6 (3a: R = CH3; 3b: R = C2H5; Cp = η5-C5H5). In addition to the NMR studies 2 and 3b have been characterized by X-ray structure analyses.
    Notes: Die Umsetzung von [Cp*Fe(P5)] (1a) mit [Cr(CO)5(THF)] bzw. [Cp(CO)2Mn(THF)] ergibt [Cp*Fe(P5){Cr(CO)5}2] (2) sowie [HCp*Fe(P5){Mn(CO)2Cp}n] (4a-d; 1-4; Cp* = η5-C5Me5). Aus 1 und [CpFe(C6H6)]PF6 lassen sich photochemisch die kationischen 30-VE-Tripeldeckerkomplexe [CpFe(μ, η5-P5)Fe(C5Me4R)]PF6 (3a: R = CH3; 3b: R = C2H5; Cp = η5-C5H5) aufbauen. Zusätzlich zu den NMR-spektroskopischen Studien wurden von 2 und 3b Kristallstrukturanalysen angefertigt.
    Additional Material: 3 Ill.
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  • 98
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 99
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1139-1145 
    ISSN: 0009-2940
    Keywords: C-(Alkylideneamino)ketene imines ; Isocyanides, C=C coupling with aminocarbene ligands ; (2-Azaallenyl)chromium complexes ; 2-Imidazolin-5-ones ; α-Amino acids ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organic Syntheses via Transition Metal Complexes, 35. - (C-Amino) Ketene Imines, 2-Imidazolin-5-ones, and α-Amino Acids from Aminocarbene Chromium Complexes and IsocyanidesC-(Alkylidenamino)ketene imines 1,4-diaza-1,2,4-pentatrienes) 8 are easily accessible by C=C coupling of isocyanides R1 - NC (2, R1 = t-C4H9, c-C5H11, CH3) with the (alkylideneamino)carbene (= 2-azaallenyl-) ligand of (6). The tendency for an insertion of 2 into M=C bonds of aminocarbene complexes strongly depends on the electronic character of the aminocarbene ligand. Electron-rich aminocarbene chromium complexes like (CO)5Cr=C(NR2)C6H5 (1, R = H, CH3), show only little tendency for an insertion but mainly give cis-(R1-NC)(CO)4Cr=C(NR2C6H5 (3) by substitution of CO. Electron-poor aminocarbene complexes like 6 (readily available on N-benzoylation of 1a) undergo a facile insertion of 2 into the M=C bond with smooth formation of 7. From 7 ketene imine 8 is spontaneously disengaged by a second equivalent of 2. The reaction works especially well with bulky isocyanides 2a, b. In the case of methyl isocyanide (2c) a [bis(imino)dihydropyrrol]chromium complex 15 is obtained as a minor product besides 8c. 15 results from a [4+1] cycloaddition of 2c at the ketene imine ligand of 7c. C-(Alkylideneamino)ketene imines 8 are easily accessible by our method. They prove to be very thermolabile in solution and spontaneously isomerize to give 2-imidazolin-5-ones 10 and C-amidoketene imines 11. Under the influence of wet silica gel keten imine derivatives 8 rapidly form α-amino acid amides 16 by hydrolysis with concomitant migration of a benzoyl group. Under the same conditions 11 also gives the „normal“ α-amino acid amides 17.
    Notes: C-(Alkylideneamino)ketenimine (1,4-Diaza-1,2,4-pentatriene) 8 wurden durch C=C-Kupplung von Isocyaniden R1-NC (2, R1 = t-C4H9, c-C5H11, CH3) mit dem (Alkylideneamino)carben-(= 2-Azaallenyl-)Ligand von (6) erstmals hergestellt. Die Bereitschaft zur Insertion von 2 in M=C-Bindungen von Aminocarbenkomplexen hängt stark von den elektronischen Eigenschaften der Aminocarbenliganden ab. Elektronenreiche (Aminocarben)chromkomplexe, wie z. B. (CO)5Cr=C(NR2)C6H5 (1, R = H, CH3), zeigen eine nur geringe Neigung zur Insertion von 2 und bilden bevorzugt cis-(R1-NC)(CO)4Cr=C(NR2C6H5 (3) unter Substitution von CO. Elektronenarme (Aminocarben)chromkomplexe hingegen, wie z. B. 6 (durch N-Benzoylierung von 1a leicht zugänglich), zeigen ausschließlich Insertion zu 7. Aus 7 wird spontan 8 freigesetzt durch Substitution mit einem zweiten Äquivalent 2. Sperrige Isocyanide 2a, c reagieren besonders einheitlich. Mit Methylisocyanid (2c) entsteht zusätzlich zu 8c der [Bis(imino)dihydropyrrol]-chromkomplex 15 unter [4+1]-Cycloaddition von 2c am Keteniminligand von 7c. C-(Alkylidenamino)ketenimine 8 sind nach unserem Verfahren einfach zugänglich; sie isomerisieren jedoch leicht zu 2-Imidazolin-5-onen 10 und C-Amidoketeniminen 11. An feuchtem Kieselgel entstehen aus 8 rasch α-Aminosäureamide 16 durch Hydrolyse unter Wanderung eines Benzoylrestes; aus 11 unter gleichen Bedingungen zusätzlich „normale“ α-Aminosäureamide 17.
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  • 100
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2177-2181 
    ISSN: 0009-2940
    Keywords: Benzonitriles ; Hetero Diels-Alder reactions, “inverse” ; Pyrazines, annulated ; Triazines, benzofuro- and benzothieno- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Donor-Substituted Benzoitriles as Side-Chain Dienophiles in the Intramolecular [4+2] Cycloaddition with Inverse Electron DemandExpanding the scope of the intramolecular Diels-Alder reaction of 1,2,4,5-tetrazines to include donor-substituted benzonitriles as side-chain dienophiles we describe synthetic routes to novel fused heterotricycles such as the benzofuro[3,2-e]-1,2,4-triazines 11a, b and the benzothieno[3,2-e]-1,2,4-triazines 14a, b, and 17. The doubly annulated pyrazines 22 and 23 are constructed by a subsequent second intramolecular Diels-Alder cycloaddition of the benzonitrile moiety with the fused 1,2,4-triazine system, starting from 11a and 14a.
    Notes: Unter Einschluß donorsubstituierter Benzonitrile als Seitenkettendienophile haben wir die Anwendungsbreite der intramolekularen Diels-Alder-Reaktion von 1,2,4,5-Tetrazinen erweitert und beschreiben Synthesewege zu neuen anellierten Heterotricyclen wie den Benzofuro[3,2-e]-1,2,4-triazinen 11a, b und den Benzothieno[3,2-e]-1,2,4-triazinen 14a, b sowie 17. Die doppelt anellierten Pyrazine 22 und 23 lassen sich durch eine nachfolgende zweite intramolekulare Benzonitril/1,2,4-Triazin-Diels-Alder-Cycloaddition mit 11a bzw. 14a als Edukten herstellen.
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