A kinetic study of alkaline hydrolysis of 1-arylimino-3-arylimino-1-butene.
作者:Machiko ONO、Reiko TODORIKI、Shinzo TAMURA
DOI:10.1248/cpb.37.2909
日期:——
Alkaline hydrolysis of 1-arylamino-3-arylimino-1-butene (1) was studied kinetically. The reaction proceeded in two ways; by hydrolysis at the 1-position of 1 to give β-arylaminocrotonaldehyde (2) and arylamine (pathway A), and by hydrolysis at the 3-position of 1 to give 4-arylamino-3-buten-2-one (3) and arylamine (pathway B), of which the former predominated. In the first step of pathway A, 1-position of 1 is attacked by hydroxide ion to give a tetrahedral intermediate which is then transformed into 2 and arylamine in the second step. Plots of the rate constants of pathway A, kA, vs. [OH-] were concave downward because the rates of the two steps are of similar order of magnitude. We were able to calculate the hydroxide ion-catalyzed rate constant (kOH1) of the first step of pathway A for 4 substrates, 1a-d. The kOH, 1s decreased with increasing electron-withdrawing effect of the aryl substituents. The reaction mechanism is discussed.
对 1-芳基氨基-3-芳基亚氨基-1-丁烯(1)的碱性水解进行了动力学研究。反应以两种方式进行:在 1 的 1 位水解,生成 β-芳基氨基巴豆醛(2)和芳基胺(途径 A);在 1 的 3 位水解,生成 4-芳基氨基-3-丁烯-2-酮(3)和芳基胺(途径 B),其中前者占主导地位。在途径 A 的第一步中,1 的 1 位受到氢氧根离子的攻击,生成四面体中间体,然后在第二步中转化为 2 和芳基胺。途径 A 的速率常数 kA 与[OH-]的关系图是向下凹的,因为两个步骤的速率数量级相似。我们能够计算出 4 种底物(1a-d)的途径 A 第一步在氢氧根离子催化下的速率常数(kOH1)。随着芳基取代基吸电子效应的增加,kOH, 1s 也随之降低。本文对反应机理进行了讨论。