混合溶剂中酶法催化合成木糖酯及其结构鉴定研究

A New Method for Enzymatic Synthesis of Xylose Diester in Two-solvent Medium and its Structural Identification

摘要:

本文建立了一种木糖酯合成的新方法，利用正己烷/吡啶（25:75，V/V）双溶剂体系作为反应介质，在溶解极性底物糖的同时保持酶的良好活性。采用固定化脂肪酶Novozyme 435在该体系中催化甲基丙烯酸乙烯酯和木糖的酯交换反应合成木糖酯。HPLC检测结果表明，当木糖与甲基丙烯酸乙烯酯的摩尔比为1:10，转速为150 r/min时该酶促反应具有较高的转化率，反应48 h后木糖转化率高于90%。GC-MS和核磁共振碳谱（13C-NMR）鉴定表明，在该反应条件下，Novozyme 435可选择性催化木糖的1′,5′-羟基酰化，得到产物为木糖的1′,5′-双酯。该研究为应用在食品、化学及造纸工业上的两性化合物的生产提供了一种有效并且环境友好的新方法。

Abstract:

A new method for synthesis of xylose esters based on solvent strategy was developed in this paper. Binary organic solvent of n-hexane and pyridine (25:75, V/V) was used as reaction system to well dissolve sugar substrate and meanwhile maintain the enzyme activity. Immobilized lipase CAL type B, Novozyme 435, was chosen as a biocatalyst to synthesize xylose ester via acylation of xylose and vinyl methacrylate. HPLC analysis showed that the highest substrate conversion (>90%) was obtained when the ratio of xylose to vinyl methacrylate, shaking speed and reaction temperature were 1:10, 150 r/min and 30 ℃, respectively. The products were structurally identified by GC-MS and 13C-NMR as a diester of xylose, 1′, 5′- dimethacrylic xylose ester. This research provided an efficient and environmentally-friendly method with application potential in production of amphoteric compounds used in food, chemical and papermaking industrils.