Superacidifiers: Assessing the Activation and the Mode of Charge Transmission of the Extraordinary Electron-Withdrawing SO<sub>2</sub>CF<sub>3</sub> and S(O)(NSO<sub>2</sub>CF<sub>3</sub>)CF<sub>3</sub> Substituents in Carbanion Stabilization
作者:François Terrier、Emmanuel Magnier、Elyane Kizilian、Claude Wakselman、Erwin Buncel
DOI:10.1021/ja0436291
日期:2005.4.1
medium effects on pK(a)'s for NO(2), SO(2)CF(3), and S(O)(=NSO(2)CF(3))CF(3) activated carbon acids. Highly contrasting behavior was thus induced by H(2)O --> Me(2)SO transfer, with a large decrease in acidity of alpha-nitro activated carbon acids but a large increase in acidity of alpha-SO(2)CF(3) analogues, leading to remarkable inversions in C-H acidity. These results support the view that in the
我们报告了结构(多核 NMR)、热力学(pK(a))和动力学(Marcus 内在反应性)研究由外环 (α) SO(2)CF(3) 组和SO(2)CF(3) 或 S(O)(=NSO(2)CF(3))CF(3) 在苯环的对位。后者发挥了巨大的酸化作用。8 pK 单位与 Me(2)SO 溶液中的 4-H 苄基三氟乙烯相比,(对应于非常高的 Hammett sigma 值 sigma(p) 约为 1.35,sigma(p)(-) 约为 2.30)。在考虑这种效应的起源时,在比较介质对 NO(2)、SO(2)CF(3) 和 S(O)(=NSO(2)CF) 的 pK(a) 的影响中得出了重要信息(3))CF(3) 活性炭酸。因此,H(2)O --> Me(2)SO 转移诱导了高度对比的行为,α-硝基活性炭酸的酸度大幅降低,但 alpha-SO(2)CF(3) 类似物的酸度大幅增加,导致 CH 酸度显着