在离子液体中锡催化多糖分解合成乳酸

Catalyzed transformation of saccharides in ionic liquids to synthesis lactic acid

淀粉和纤维素能够被四氯化锡催化转化为乳酸甲酯和乳酸,使用离子液体是实现多糖转化的关键。在实验中考察了催化剂、离子液体、反应时间和反应温度对于总乳酸收率的影响。实验结果显示,在1,3-二甲基咪唑硫酸甲酯盐中的淀粉在140℃条件下反应2h可获得54%总乳酸收率,纤维素的收率为15.1%。果糖在同样的反应条件下收率为95%,葡萄糖为64%,这意味着反应机理可能为纤维素和淀粉首先降解为葡萄糖,然后异构为果糖,最终果糖分解为乳酸。

Methyl lactate and lactic acid were synthesized by hydrolysis of starch and cellulose using SnCl4 catalyst.The use of ionic liquids as the solvent was the key factor for the successful hydrolysis.The influence of catalyst,type of ionic liquids,reaction temperature and time on the product yield were investigated.The results indicated that methyl lactate and lactic acid can be obtained via liquid phase transformation catalyzed by SnCl4 in 1,3-dimethylimidazolium methylsulfate ionic liquid at 140℃ for 2 h,the yield was 54% for starch and 15.1% for cellulose conversion.Fructose could be directly converted to lactic acid with almost stoichiometric yield,but only 64% for glucose.So,starch and cellulose were firstly catalyzed degradation to glucose that then was isomerized to fructose,and fructose decomposed to lactic acid finally.