Experimental and Theoretical Studies on the Nucleofugality Patterns in the Aminolysis and Phenolysis of <i>S</i>-Aryl <i>O</i>-Aryl Thiocarbonates
作者:Enrique A. Castro、Margarita Aliaga、Paola R. Campodónico、Marjorie Cepeda、Renato Contreras、José G. Santos
DOI:10.1021/jo902005y
日期:2009.12.4
theoretical analysis based on the group electrophilicity index, a reactivity descriptor that may be taken as a measure of the ability of a group or fragment to depart from a molecule with the bonding electron pair. The theoretical analysis is in accordance with the experimental results obtained and predicts relative nucleofugalities of O-aryl vs. S-aryl groups in a series of diaryl thiocarbonates not experimentally
所述的反应小号-苯基,小号(4-氯苯基),和-小号- ((2,3,4,5,6-五氟苯基)4-硝基苯基硫代碳酸盐9,11,和16,分别地)具有一系列的二次脂环族(SA)胺和S-(4-甲基苯基)4-硝基苯基硫代碳酸酯(8)以及具有一系列酚的化合物9和11在25.0°C下于44 wt%乙醇-水中进行动力学研究离子强度为0.2M。分光光度法跟踪反应。在亲核试剂过量的情况下,伪一阶速率系数(k obsd) 被发现。对于所有这些反应,在恒定pH值下k obsd与游离胺或酚盐阴离子浓度的关系图是线性的,斜率(k N)与pH值无关。所述布朗斯台德型图(日志ķ Ñ与p ķ一个的亲核试剂的共轭酸),用于氨解9,11,和16是线性的,斜率分别为β= 0.85、0.90和0.67。前两个斜率与通过两性离子四面体中间体的逐步机理相符,该中间体的断裂是决定速率的。后一个β值与协调机制一致。所述布朗斯台德型曲线为硫代碳酸盐的酚解8,9,和11分别β=