The esterification reaction of amino acids and benzyl alcohol was used as the model to study the amino acid esterification process catalyzed by hydrogen chloride. The water from reaction was removed by azeotropic distillation using 1,2-dichloroethane as solvent, to promote the esterification reaction and the target product amino acid benzyl ester hydrochloride was obtained by recrystallization. When the molar ratio of amino acid to benzyl alcohol was 1.00:1.08, the reaction temperature 83℃, the reaction time 4-6 h, the yield was about 65%. In addition, when the amino acid was esterified with a low boiling point alcohol such as methanol, the equilibrium conversion rate of the reaction was improved by using the alcohols as the reactant and water-carrying agent simultaneously. The distilled alcohol was then re-added to the reaction system after the water removal treatment, and the yield of the amino acid ester hydrochloride was of 75% to 85%. The reaction-separation coupling technique improved the yield and purity of the product, shortened the reaction time and reduced the amount of raw materials.%以氨基酸与苯甲醇的酯化反应为模型反应,研究了氯化氢催化下的氨基酸酯化工艺.采用1,2-二氯乙烷作为溶剂,共沸蒸馏带出生成的水,以促进酯化反应完成,再经重结晶后得到目标产物氨基酸苄酯盐酸盐.当氨基酸与苯甲醇物质的量之比为1.00:1.08,反应温度83℃,反应时间4~6 h时,收率可达65%左右.此外,在氨基酸与甲醇等低沸点醇进行酯化时,采用醇同时作为反应物和带水剂的方法,提高反应的平衡转化率,并将蒸馏出的醇经过除水处理后重新加入反应体系中,氨基酸酯盐酸盐收率在75%~85%.利用反应-分离耦合技术提高了产物的收率与纯度,缩短了反应时间,减少了原料的用量.
展开▼
