H_3O^+催化苯并噻吩-2-甲酸脱羧反应  

Decarboxylation reaction of a-benzothiophene carboxylic acid catalyzed by H_3O^+

作　　者：宋明芝[1,2] 张在龙 范传刚[2] 李大枝[2] 卞贺[2] 张士国[2] 

机构地区：[1]中国石油大学理学院化学系,山东青岛266555 [2]滨州学院化学系,滨州市材料化学重点实验室,山东滨州256600

出　　处：《计算机与应用化学》2013年第9期1021-1027,共7页Computers and Applied Chemistry

基　　金：中央高校基本科研业务费专项资金资助(14CX06002A);滨州学院科研基金项目(BZXYG1305)

摘　　要：采用密度泛函理论(DFT)的B3LYP方法,在6-311++G(d,p)基组水平上,研究了在无催化剂、H_2O参与、H_3O^+参与3种条件下苯并噻吩-2-甲酸脱羧的微观反应机理。结果表明,在无催化剂或H_2O参与条件下,苯并噻吩-2-甲酸的脱羧反应的活化能分别为249.1和246.5 kJ.mol^(-1)。在H_3O^+参与的反应中,反应主要经历了噻吩环α-C的质子化、羧基的水合以及C-C键断开的过程,羧基的水合反应为决速步骤,其活化能为177.6 kJ·mol^(-1),而C-C键断开所需克服的能垒仅为32.8 kJ·mol^(-1),从而表明H_3O^+能促进反应的进行。Density Function Theory （DFT） B3LYP method was employed to study the mechanism about three kinds of decarboxylation （without catalyst, with the assistance of H2O, or with the assistance of H3O＋） of benzothiophene-2-carboxylic acid with the 6-311＋＋G（d, p） basis sets. The potential energy of the decarboxylation of benzothiophene-2-carboxylic acid at the condition without any catalyst or aided with H/O was calculated to be 249.1 kJ·mol-1 and 246.5 kJ·mol-1, respectively. When aided with H3O＋, the reaction mainly through the ct-protonated of the thiophene ring, the hydration of the carboxyl group and the breaking of the C-C bond. The reaction was controlled by the hydration of the carboxyl group, the energy barrier was 177.6 kJ.moll, and the activation energy of the rupture of C-C bond was only 32.8 kJ·mol-1. Which suggest that the decarboxylation of benzothiophene-2-carboxylic acid may be catalyzed effectively by H3O＋.

关 键 词：苯并噻吩-2-甲酸 催化脱羧 密度泛函理论 电子密度拓扑分析 

分 类 号：O641[理学—物理化学]