Substituent Effect Studies of Aryl-Assisted Solvolyses. I. The Acetolysis of 2,2-Bis(substituted phenyl)ethyl<i>p</i>-Toluenesulfonates
作者:Mizue Fujio、Yasuyuki Maeda、Mutsuo Goto、Yoshihiro Saeki、Masaaki Mishima、Yuho Tsuno
DOI:10.1246/bcsj.66.3015
日期:1993.10
The substituent effect on the acetolysis of 2,2-bis(substituted phenyl)ethyl p-toluenesulfonates at 90.10 °C can be described accurately in terms of the Yukawa–Tsuno (LArSR) relationship, giving a ρ value of −4.44 and an r value of 0.53. The substituent effect correlation of this system carrying two aryls is quite comparable to that of the 2-methyl-2-phenylpropyl system carrying a single aryl group, suggesting the close similarity in the structure of the transition states between the systems. The results can be reasonably accounted for on the basis of the accepted mechanism of this reaction, involving a rate-determining aryl-assisted transition state where only one aryl group of the two β-aryl groups participates.
在90.10 °C下,2,2-双(取代苯基)乙基对甲苯磺酸酯的醇解反应中,取代基效应可以通过Yukawa–Tsuno(LArSR)关系进行准确描述,给出了ρ值为−4.44和r值为0.53。该系统中包含两个芳香基的取代基效应与包含单个芳香基的2-甲基-2-苯基丙基系统的相关性相当可比,这表明这两个系统的过渡态结构非常相似。根据这种反应的公认机制,结果可以合理地解释为涉及一个速率决定的芳基辅助过渡态,其中两个β-芳基中的仅一个芳基参与反应。