Regioselectivity and the Nature of the Reaction Mechanism in Nucleophilic Substitution Reactions of 2,4-Dinitrophenyl X-Substituted Benzenesulfonates with Primary Amines
作者:Ik-Hwan Um、Jin-Young Hong、Jung-Joo Kim、Ok-Mi Chae、Sun-Kun Bae
DOI:10.1021/jo034190i
日期:2003.6.1
mechanism. The second-order rate constants for the S-O bond fission result in good linear Yukawa-Tsuno plots for the aminolyses of 2,4-dinitrophenyl X-substituted benzenesulfonates. However, the second-order rate constants for the C-O bond fission show no correlation with the electronic nature of the sulfonyl substituent X, indicating that the C-O bond fission proceeds through an S(N)Ar mechanism in which the
已经测量了2,4-二硝基苯基X-取代的苯磺酸盐与一系列伯胺的反应的二级速率常数。亲核取代反应通过竞争性SO和CO键裂变途径进行。SO键裂变主要发生在与高碱性胺或与在磺酰基部分中具有强吸电子基团的底物的反应中。另一方面,对于与低碱性胺或与磺酰基部分中具有强供电子基团的底物的反应,CO键裂变会相当多地发生,这强调区域选择性受胺的碱性和氢的电子效应的支配。磺酰基取代基X。SO键裂变的表观二阶速率常数已导致2,4-二硝基苯基苯磺酸盐与10种不同伯胺反应的非线性布朗斯台德图,这表明速率改变步骤在改变时发生变化胺的碱度。与SO键裂变路径相关的微观速率常数(k(1)和k(2)/ k(-)(1)比率)支持所提出的机制。SO键裂变的二级速率常数导致2,4-二硝基苯基X-取代的苯磺酸酯的氨解酶具有良好的线性Yukawa-Tsuno图。但是,CO键裂变的二级速率常数与磺酰基取代基X的电子性质无关,