【作者】 沈国华；

【导师】 吴坚平； 杨立荣；

【作者基本信息】 浙江大学 ， 微生物与生化药学， 2008， 硕士

【摘要】 离子液体是指在室温下完全由离子组成的有机液体物质,因其具有无毒、无蒸气压、无可燃性、热稳定性高、可取代挥发性有机溶剂、可循环使用等独特性质而被用于分离工程、化学反应、生物催化等过程。离子液体符合绿色化学的原则,因而被称为绿色溶剂。手性化合物由于其独特的光学活性,广泛应用于医药、食品、化工、农药等领域,随着对不同光学异构体药物药理作用的研究进展和对外消旋药物申报和使用的种种限制,手性药物成为近年来研究的热点和方向。光学纯醇类化合物是手性药物合成的重要中间体。利用微生物或其细胞内的氧化还原酶催化潜手性酮的不对称还原已成为制备高光学纯度手性醇的重要方法。本文以2′-氯-苯乙酮作为模型底物,研究了离子液体/水两相体系中酵母全细胞催化芳香酮类化合物不对称还原反应的特性,并通过条件优化提高了反应效率,强化了反应过程。对各不同反应体系进行了比较,结果表明离子液体[BMIM]PF₆/水两相反应体系相比于有机溶剂/水两相体系和纯水相体系更有利于酵母细胞的还原反应,尤其是在较高的底物浓度下。当底物浓度高达64.72 mmol/L(10g·L^-1)时,用游离酵母细胞作为生物催化剂,在最佳条件下,转化率可达到54.5%,是纯水相体系中反应转化率的300%,产物e.e.值为98.6%左右。将酵母细胞用海藻酸钙固定化后催化能力有所提高。在此基础上对固定化酵母在离子液体/水两相体系中的反应条件进行了优化,确定较佳条件为:固定化细胞浓度360g/L,离子液体/水两相比率1:15,缓冲液pH7.2,摇床转速200rpm,反应时间45h,反应温度30℃,反应过程中分两次各添加10%的葡萄糖。在最优条件下,64.72 mmol/L的底物浓度时反应的最大转化率达到75.4%,明显提高了反应效率。产物的e.e.值保持在99.1%左右。更多还原

【Abstract】 Ionic liquids are salts consisting of positively charged cations and negatively charged anions.They are liquids below 100℃.Depending upon their nontoxicity,low volatility,nonflammability,high thermal stability,recycle using and the substituent for other volatile organic solvents,they are widely used in processes of separation, chemical reaction and biocatalysis.For their specific properties.Ionic liquids are called "green solvent".Chiral compounds have been widely applied in pharmaceuticals,food,pesticide and chemical industry due to their special optical activity.With the progress in pharmacology of chiral pharmaceuticals and the strict regulation on the application of new racemic drug in recent years,the research and development of chiral pharmaceuticals have become the new focus and direction.Enantiomerically pure alcohols are important intermediates for synthesis of pharmaceuticals.Asymmetric reduction of pro-chiral ketones catalyzed by microorganism or the oxidoreductase in the cell has been an important method of synthesis enantiomerically pure alcohols.In this work,using 2’-chloroacetophenone as the mode substrate,the reaction characteristics of the reduction of aromatic ketone by whole cell of yeast in Ionic liquid/aqueous biphasic system were studied.The conversion was improved by optimizing reaction conditions.By the comparation of different system,it was proved that the ionic liquid [BMIM]PF₆/aqueous biphasic system is more suitable for whole cell of yeast’s reduction than other organic solvent/aqueous biphasic system and pure aqueous phase system,especially when the substrate concentration was high.Under the substrate concentration of 64.72 mmol/L(10g·L^-1)and catalyzed by free cells,the conversion was 54.5%after optimizing,nearly 300%as that in the pure water system.The production e.e.value was 98.6%.After being immobilized by Sodium alginate-CaCl₂,the yeast cell’s catalysis activity was increased.Based on this conclusion,the reaction conditions were optimized.The optimal conditions were:Immobilized cell’s content of 360 g/L; V_I.L/V_aqof 1:15;buffer pH of 7.2;shaker frequency of 200rpm;reaction time of 45h; reaction temperature of 30℃;adding glucose of 10%twice.Under these conditions, the maximum conversion was 75.4%with the substrate concentration of 64.72 mmol/L.The production e.e.value was around 99.1%.更多还原