Mechanistic studies in strong acids. VIII. Hydrolysis mechanisms for some thiobenzoic acids and esters in aqueous sulfuric acid, determined using the excess acidity method
作者:Robin A. Cox、Keith Yates
DOI:10.1139/v82-438
日期:1982.12.15
The excess acidity method has been applied to hydrolysis rate data, obtained as a function of medium composition, for four thiobenzoic acids, thioacetic acid, eight ethyl thiolbenzoates, and eight ethyl thionbenzoates in aqueous sulfuric acid. The mechanistic behaviour thus revealed has both similarities to and differences from that of a typical ester like ethyl benzoate, which gives benzoic acid by
过量酸度法已应用于硫酸水溶液中四种硫代苯甲酸、硫代乙酸、八种硫代苯甲酸乙酯和八种硫代苯甲酸乙酯的水解速率数据,该数据作为介质组成的函数获得。由此揭示的机械行为与典型的酯类(如苯甲酸乙酯)既有相似之处,也有不同之处,后者在弱酸中通过涉及两个水分子的 A-2 反应生成苯甲酸,在强酸中通过 A-1 酰基离子形成. 硫代酸遵循这种行为,除了 A-2 过程涉及三个水分子,并且机械转换发生在 60% 而不是 80% 的酸中。硫代苯甲酸乙酯的 A-2 过程缓慢;主要的水解机制是酰基离子的形成,不是在 A-1 反应中,而是通过协调的 A-SE2 过程,包括质子转移到硫和碳-硫键断裂。主要的质子转移剂是未解离的硫酸分子。苯甲酸硫...