Effect of Substituent on Regioselectivity and Reaction Mechanism in Aminolysis of 2,4-Dinitrophenyl X-Substituted Benzenesulfonates
作者:Ik-Hwan Um、Jin-Young Hong、Jin-Ah Seok
DOI:10.1021/jo048227q
日期:2005.2.1
a kinetic study for the nucleophilic substitution reactions of 2,4-dinitrophenyl X-substituted benzensulfonates (X = 4-MeO, 1a, and X = 4-NO2, 1c) with a series of primary amines in 80 mol % H2O/20 mol % DMSO at 25.0 °C. The reactions proceed through S−O and C−O bond fission pathways competitively. The fraction of the S−O bond fission increases as the attaching amine becomes more basic and the substituent
我们对的2,4-二硝基苯基X取代的benzensulfonates亲核取代反应的动力学研究报告(X = 4-的MeO,1A,和X = 4-NO 2,1C),在80摩尔%一系列伯胺的在25.0°C下,H 2 O / 20 mol%DMSO。反应通过S-O和C-O键裂变途径竞争地进行。S-O键裂变的分数随连接胺变得更碱性和取代基X从4-MeO变为4-NO 2而增加,表明区域选择性是由取代基X的电子性质以及胺的碱度决定的。已建议S-O键裂变通过加成中间体进行,其中速率确定步骤(RDS)的变化为p K a °= 8.9±0.1。取代基X的电子性质影响k N S - O和k 1值,但不影响k 2 / k - 1比和p K a°值明显。通过供电子取代基和亲电子中心之间的共振相互作用,稳定基态(GS)的原因是1a的反应性比1c降低。C-O键裂变的二阶速率常数与取代基X的电子性质不相关。距离效应和反应机理的性质被认为是造成这种不相关的原因。