作者:Neil S. Isaacs、Tariq S. Najem
DOI:10.1139/v86-190
日期:1986.6.1
leaving group may undergo hydrolysis by elimination to an intermediate ketene, which rapidly hydrates. Examples are found in p-hydroxybenzoate, malonate, and acetoacetate esters of nitrophenols. The evidence for this mechanism (E1cb type) includes the independence of rate with pH in the region of dissociation of the acidic proton and, in particular, positive volumes of activation that contrast sharply
具有酸性质子 α 的羧基(或在乙烯基情况下)和良好的离去基团的酯可以通过消除为中间体乙烯酮而发生水解,乙烯酮会迅速水合。例子见于硝基苯酚的对羟基苯甲酸酯、丙二酸酯和乙酰乙酸酯。这种机制(E1cb 类型)的证据包括酸质子解离区域中速率与 pH 值的独立性,特别是正激活体积与更常见的 BAc2 水解机制的典型负值形成鲜明对比。