The <i>β</i>
-silicon effect. 4: substituent effects on the solvolysis of 1-alkyl-2-(aryldimethylsilyl)ethyl trifluoroacetates
作者:Ryoji Fujiyama、Md. Ashadul Alam、Aiko Shiiyama、Toshihiro Munechika、Mizue Fujio、Yuho Tsuno
DOI:10.1002/poc.1667
日期:2010.9
2‐(aryldimethylsilyl)‐1‐tert‐butylethyl trifluoroacetates were determined conductimetrically in 60% (v/v) aqueous ethanol. The effects of aryl substituents at the silicon atom on the solvolysis rates at 50 °C were correlated with parameters of r+ = 0.15 with the Yukawa–Tsuno equation, giving ρ values of −1.5 for both secondary α‐Me and α‐tert‐Bu systems. The ρ values for those secondary systems are less negative than
在60%(v / v)乙醇水溶液中以电导法测定了2-(芳基二甲基甲硅烷基)-1-甲基乙基和2-(芳基二甲基甲硅烷基)-1-叔丁基乙基三氟乙酸盐的溶剂分解速率。在对溶剂分解率硅原子芳基取代基,在50的影响℃,用相关的参数- [R + = 0.15与汤川-津野方程,得到ρ的值-1.5两个次级α -Me和α -叔- Bu系统。该ρ对于那些通过Eaborn(非垂直)机制产生的2-(芳基二甲基甲硅烷基)乙基系统,这些二级系统的值小于-1.75的负值,而对于2-(芳基二甲基甲硅烷基)-1-的2-(芳基二甲基甲硅烷基)乙基系统的负值明显大于-0.99。应通过Lambert(垂直)机理进行处理的苯乙基体系。β-甲硅烷基取代基效应的反应常数(ρ)与一系列β-甲硅烷基底物的溶剂分解反应性之间存在相当线性的关系。α- Me和叔-Bu底物的溶剂化过程以过渡态(TS)进行,且β的程度可观硅酮参与,靠近Eaborn