离子液体协同催化合成游离氨基酸酯

Synthesis of Free Amino Acid Esters Co-catalyzed by Ionic Liquid

以L-氨基酸和醇为原料,酸性离子液体辅以少量强酸性阳离子交换树脂作催化剂,直接酯化合成了8种游离的L-氨基酸酯,并用1HNMR对产物进行了表征。通过L-苯丙氨酸正丁酯的合成对离子液体的活性进行了考察,结果表明,所选用的11种离子液体在反应过程中均起到了一定的催化作用和助溶作用。其中,[Hmim][HSO4]效果较好,在重复使用后,显示了较好的稳定性,是氨基酸酯化反应理想的催化剂和助溶剂。

Eight kinds of free L-amino acid esters including L-phenylalanine ethyl ester,L-phenylalanine n-butyl ester,L-phenylalanine i-butyl ester,L-tyrosine n-butyl ester,L-tyrosine i-butyl ester,L-tyrosine i-amyl ester,L-aspartic n-butyl diester and L-aspartic i-butyl diester were synthesized by direct esterification of L-amino acid and alcohol with acidic ionic liquid assisted by strong acidic cation resin as catalyst.The structures of free L-amino acid esters were characterized by 1HNMR.Optimal reaction conditions were obtained when synthesizing L-phenylalanine n-butyl ester.Among eleven kinds of the acidic ionic liquids used in this case,indicated excellent activity and the catalyst is easily regenerated and reused.By this token,it exhibits its potential application as catalyst and co-solvent in the esterification of amino acid.