扁桃酸的酶促光学拆分

Enzyme-catalyzed optical resolution of mandelic acid

对在非水体系中,利用脂肪酶催化水解扁桃酸乙酯外消旋混合物拆分R(-)-扁桃酸进行了初步的研究.筛选出脂肪酶N435作为催化剂,叔丁醇作为溶剂.确定了最适的反应条件:脂肪酶N435浓度为2·5g·L-1,RS(-+)-扁桃酸乙酯浓度为0·25mol·L-1,水∶RS(-+)-扁桃酸乙酯的摩尔比为5∶1,反应温度为40℃,摇床转速为200r·min-1,反应时间为24h.在此条件下,R(-)-扁桃酸乙酯的转化率为41·6%,对映体过量百分率达84·0%.考察了底物R(-)-扁桃酸乙酯和产物R(-)-扁桃酸对反应的抑制作用,在此基础上运用顺序机制和拟稳态法,建立了反应的动力学模型,模拟计算结果和实验结果吻合较好.

Lipase-catalyzed optical resolution of R（-）-mandelic acid via RS （±↓）-ethyl mandelate in nonaqueous media was studied. Lipase N435 was screened as the catalyst, and tert-butanol was used as the solvent. When lipase N435 was 2.5 g·L^-1, RS （±↓）-ethyl mandelate was 0. 25 mol· L^-1, water to RS（±↓）-ethyl mandelate was 5 ： 1 （molar ratio）, the reaction temperature was 40℃, the speed of agitation was 200 r·min^-1, the R（-）-ethyl mandelate conversion could reach 41.6%, and enantiomeric excess （e. e. ） was 84.0% after 24 h. Inhibition by the substrate and product was also investigated. A kinetic model was established by following the ordered bi-bi mechanism and quasi-steady state. Good agreement between experimental data and the simulation results was obtained.