研究了三氯乙酸钠与各种有机硅氢化物在1,2-二甲氧基乙烷中的反应,形成了α-三有机甲硅烷基二氯甲烷,产率为20%至50%。通过竞争反应确定在这些二氯卡宾的插入反应中这些氢硅烷的相对速率常数。一系列烷基取代的氢硅烷的相对反应性与硅上取代基的Taftσ*常数高度相关,ϱ *值为-1.07,一系列芳基取代的氢硅烷也显示出log k rel良好的线性相关性值具有Taftσ*常数,giving *值为-1.18。反应中的氢同位素效应k H / k D1.26±0.02。基于观察到的结果,可以得出结论,Cy 2插入SiH键中是通过三中心协同过程进行的,该过程中过渡态的电荷分离不大,正如塞弗特(Seyferth)对相关的PhHgCCl 2提出的那样。 Br / XC 6 H 4 SiMe 2 H反应。
Cleavage of α-halo-substituted alkyl groups from silicon. The mechanism of catalysis by ammonia buffer
作者:J. Chojnowski、W. Stańczyk
DOI:10.1016/s0022-328x(00)86286-5
日期:1975.10
from silicon in n-propanol—water in the presence of ammonia buffer. The separate rate constants for the concurrent base-catalysed and base-plus-nucleophile-catalysed processes have been determined for the compounds XC6H4(Me2)SiCHCl2 with X = H, p-MeO, p-Me, p-Cl, m-Cl, m-CF3 and a good correlation with σ-constants found for both types of catalysis. Solvent isotope effects and steric effects of substituents