Unraveling Structure−Reactivity Relationships in S<sub>N</sub>V Reactions: Kinetics of the Reactions of Methoxybenzylidenemalononitrile, 2-(Methylthiobenzylidene)-1,3-indandione, 2-(Benzylthiobenzylidene)-1,3-indandione, and Methyl β-Methylthio-α-nitrocinnamate with OH<sup>-</sup> and Thiolate Ions in Aqueous DMSO
作者:Claude F. Bernasconi、Rodney J. Ketner、Mark L. Ragains、Xin Chen、Zvi Rappoport
DOI:10.1021/ja003536t
日期:2001.3.1
The kinetics of the title reactions were determined in 50% DMSO-50% water (v/v) at 20 degrees C; n-BuS-, HOCH2CH2S-, and MeO2CCH2S- were used as thiolate ions. The reactions with the thiolate ions gave rise to two separate kinetic processes. The first refers to rapid, reversible attachment of RS- to the substrate leading to a tetrahedral intermediate (k1RS), k(-1)RS, the second to the conversion of
标题反应的动力学在 50% DMSO-50% 水 (v/v) 中于 20 摄氏度进行测定;n-BuS-、HOCH2CH2S- 和 MeO2CCH2S- 用作硫醇盐离子。与硫醇盐离子的反应产生两个独立的动力学过程。第一个是指 RS- 与底物的快速、可逆连接,导致四面体中间体 (k1RS),k(-1)RS,第二个是中间体转化为产物 (k2RS)。在大多数情况下,可以确定所有速率常数(k1RS、k(-1)RS 和 k2RS。结合先前研究的结果,详细讨论了活化取代基和离去基团对速率常数和平衡常数的影响与本征速率常数一样,与 OH- 的反应仅允许测定 k1OH 对底物的亲核攻击;