对羧基苯乙酸的酯化过程及其动力学研究

Process and kinetics of esterification of 4-carboxylbenzeneacetic acid

对羧基苯乙酸的两个羧基活性不同,对位羧基由于苯环的共轭作用,其酯化活性较低。本研究以对羧基苯乙酸为原料,分别在HD-8强酸性阳离子树脂与浓硫酸催化下制备对羧基苯乙酸甲(乙)酯与对甲(乙)氧羰基苯乙酸甲(乙)酯,收率分别为85.4%(85.7%)与84.1%(88.1%);优化了制备对乙氧羰基苯乙酸乙酯的反应条件;并对浓硫酸催化下的酯化过程做了动力学研究,测得1位羧基的活化能Ea1为57.53 kJ/mol,4位羧基活化能Ea2为131.54 kJ/mol。

The activity of 4-carboxylate of 4-carboxylbenzene- acetic acid is lower since the conjugationof benzene ring. The esterification of 4-carboxyl benzeneacetic acid and methanol （ethanol） was carried out using HD-8 strong-acid cation ex- change resin and H2SO4 as catalyst to prepare benzeneacetic acid, 4-carboxy-, 1-methyl （ethyl） ester and benzeneacetic acid,4-methoxycarbonyl （cthoxycarbonyl）-,methyl （ethyl） ester, and the yield is 85.4% （85.7%） and 84. 1% （88.1%）, respectivily ;then the reaction conditions for prep- aration of 4-ethoxycarbonyl-, ethyl ester was optimized. The kinetics of the esterification of these two different carboxyl was also studied,the activation energy of 1-carboxyl is Ea1 = 57.53 kJ/mol and 4-carboxyl Ea2 = 131.54 kJ/mol, respec- tively.