叔丁醇体系中脂肪酶催化合成蔗糖乙酸酯

Lipase-Catalyzed Synthesis of Sucrose Acetate in Tert- Butyl Alcohol

以蔗糖和乙酸乙烯酯为底物,脂肪酶催化合成蔗糖乙酸酯并分离得到了三氯蔗糖生产的关键中间体蔗糖-6-乙酸酯。今对催化合成蔗糖乙酸酯的反应溶剂进行比较,确定叔丁醇为较好的反应介质,详细考察了各反应参数:酶种类、初始水活度、底物摩尔比、酶用量、反应温度和时间对酯化反应效果的影响,确定了该反应体系的最优工艺条件:蔗糖40mmol?L?1,乙酸乙烯酯/蔗糖(mol/mol)=5,初始水活度aw=0.75,温度60℃,20%(w/w,酶/蔗糖)固定化脂肪酶LipozymeTLIM催化,反应24h后酯化率达84.70%。通过硅胶柱层析分离得到高纯度的其中一种产物,经二维核磁(2D-NMR)结构分析后,确定其为蔗糖-6-乙酸酯,占总酯化产物的质量达48.30%。

Lipase catalyzed synthesis of sucrose acetates from sucrose and vinyl acetate was studied and the synthesized product sucrose-6-acetate, a critical intermediate of sucralose production, was separated. In the research, various reaction solvents and several lipases were screened; finally the tert-butyl alcohol and Lipozyme TLIM were selected respectively as the best solvent and lipase. The effects of the reaction parameters were investigated and the optimum operation conditions are obtained as follows： sucrose of 40 mmol·L^-1, vinyl acetate/sucrose （mol/mol） =5, initial water activity aw= 0.75, reaction temperature of 60 ℃ and the lipase/sucrose ratio of 20%（wt）. Under above optimum conditions, the maximum esterification ratio can reach 84.70% after 24 h. The product sucrose-6-acetate was separated by silica gel column chromatography and identified by 2D-NMR, and the obtained ratio of the sucrose-6-acetate is 48.30% of the crude sucrose acetates.