The enantioselective esterification of racemic 1-trimethylsilylethanol with acids catalyzed by lipase in organic solvent was successfully performed. The influence of some factors on the reaction was investigated. Amon...The enantioselective esterification of racemic 1-trimethylsilylethanol with acids catalyzed by lipase in organic solvent was successfully performed. The influence of some factors on the reaction was investigated. Among the four lipases explored, Candida rugosa lipase (CRL) showed the highest activity and enantioselectivity. Octanoic acid was the best acyl donor among the eleven acids studied and n-hexane was the most suitable medium for the reaction. The optimum shaking rate and temperature were found to be 150r·min-1 and 20℃ to 30℃, respectively. The enantiomeric excess of the remaining (5)-(-)-1-trimethylsilylethanol was 93% when substrate conversion was 53% upon incubation of the reaction mixture at 30℃, 150r·min-1 for 12 h.展开更多
Grinding is a most important machining method for Si3N4 ceramics. Utilizing interracial chemistry reaction membrane between grinding fluid and Si3N4 ceramics can reduce friction factor, soften surface layer and meanwh...Grinding is a most important machining method for Si3N4 ceramics. Utilizing interracial chemistry reaction membrane between grinding fluid and Si3N4 ceramics can reduce friction factor, soften surface layer and meanwhile improve the grinding efficiency, which is a bran-new research direction. This article, based on high efficiency grinding of Si3N4 ceramics by the way of half plasticity removal, descanted on the assistant function of interface chemistry reaction to improve the removal rate of Si3N4 ceramics in the application of organic grinding fluids represented by alcohols grinding fluid. To target action mechanism research, it applies the methods of classification, comparison and induction, and advanced test equipments to explore the effects of long, short carbochain alcohol and their water solutions acting as grinding fluids. In addition, it also discusses the effective function of three groups of organic matters such as perhalogeno hydrocarbon, cationic surfactant and tetra ethoxysilane acting as grinding fluid components from different angles, reveals their mechanisms of action, and supplies theoretical basis for the development of machining ceramic grinding fluid of high efficiency, low cost.展开更多
基金Supported by the National Natural Science Foundation of China (No. 20076019) the Natural Science Foundation of Guangdong Province (No. 000444).
文摘The enantioselective esterification of racemic 1-trimethylsilylethanol with acids catalyzed by lipase in organic solvent was successfully performed. The influence of some factors on the reaction was investigated. Among the four lipases explored, Candida rugosa lipase (CRL) showed the highest activity and enantioselectivity. Octanoic acid was the best acyl donor among the eleven acids studied and n-hexane was the most suitable medium for the reaction. The optimum shaking rate and temperature were found to be 150r·min-1 and 20℃ to 30℃, respectively. The enantiomeric excess of the remaining (5)-(-)-1-trimethylsilylethanol was 93% when substrate conversion was 53% upon incubation of the reaction mixture at 30℃, 150r·min-1 for 12 h.
文摘Grinding is a most important machining method for Si3N4 ceramics. Utilizing interracial chemistry reaction membrane between grinding fluid and Si3N4 ceramics can reduce friction factor, soften surface layer and meanwhile improve the grinding efficiency, which is a bran-new research direction. This article, based on high efficiency grinding of Si3N4 ceramics by the way of half plasticity removal, descanted on the assistant function of interface chemistry reaction to improve the removal rate of Si3N4 ceramics in the application of organic grinding fluids represented by alcohols grinding fluid. To target action mechanism research, it applies the methods of classification, comparison and induction, and advanced test equipments to explore the effects of long, short carbochain alcohol and their water solutions acting as grinding fluids. In addition, it also discusses the effective function of three groups of organic matters such as perhalogeno hydrocarbon, cationic surfactant and tetra ethoxysilane acting as grinding fluid components from different angles, reveals their mechanisms of action, and supplies theoretical basis for the development of machining ceramic grinding fluid of high efficiency, low cost.
