The beta-silicon effect in the solvolyses of beta-silylethyl systems in terms of the Yukawa-Tsuno equation

Abstract

We reported that the beta-silicon participation in solvolyses was explained by a continuous spectrum of transition states from the kc mechanism to Si-bridged one based on the continuous change of the rho value with stability of reaction center. In order to confirm the continuous changes of Si-bridging mechanism, the solvolysis of beta,beta-dimethyl system is chosen in this study. The solvolysis rates of 2-(aryldimethylsilyl)-2-methylpropyl 3,5-dinitrobenzoates in 60% aq. EtOH at 50 ^oC were analyzed by the Y-T Eq. to give a rho value of -1.8 as high as that for the primary system, referable to the Si-bridged mechanism.