由于相似的动力学反应曲线,从多官能化前体开始合成硅烷通常会遇到化学选择性低的问题,导致难以分离的副产物的形成。相反的方法是基于非反应性四烷基硅烷作为起始材料的方法,但目前尚未开发。据报道,利用我们实验室最近开发的硅离子引发的四烷基硅烷化学选择性卤脱烷基化,该方案的扩展,即从四烷基硅烷直接合成二卤硅烷。经过一系列卤代脱氢和卤代脱烷基化,三烷基氢硅烷也可以转化为二卤代硅烷。市售的 1,2-二卤乙烷充当卤素源,并通过苯溶剂的 S E Ar 取代参与生成催化活性芳烃离子。假设形成不常见的卤素取代的硅离子作为中间体,这可能是需要升高反应温度的原因。
An examination of the substitution chemistry of di-n-hexyldichlorosilane
摘要:
Various nucleophiles were reacted with the substrate di-n-hexyldichlorosilane as model reactions for the substitution of two geminal Si-CI bonds on polymer backbone repeat units. The reactants examined were chosen on the basis of steric bulk, electronic factors, and resulting stability of the product. Linear and branched alcohol nucleophiles used in conjunction with an amine proton acceptor produced disubstituted products in moderate yields, whereas bulkier reagents substituted only one silicon-chlorine bond. Due to their vastly increased nucleophilicity, alkyllithium reagents were found to have increased activity and were found to produce very high yields. (C) 2001 Elsevier Science B.V. All rights reserved.