Nucleophilic displacement versus electron transfer in the reactions of alkyl chlorosilanes with electrogenerated aromatic anion radicals
作者:Saida Soualmi、Mamadou Dieng、Ali Ourari、Diariatou Gningue-Sall、Viatcheslav Jouikov
DOI:10.1016/j.electacta.2015.01.182
日期:2015.3
ways, following classical bimolecular schemes. The ratio of one-electron transfer (ET) to a two-electron process (SN2-like nucleophilic attack of the reduced form of mediator on the chlorosilane, with k2 ≅ 102-108 M−1 s−1) is inversely related to the steric availability of Si for nucleophilic displacement reactions. The nucleophilic substitution pathway mainly results in mono- and disilylated aromatic
一系列芳族化合物(C 6 H 5 CN,C 6 H 5 COOEt,蒽,9,10-二甲基-,9,10-二苯基-和9-苯基蒽,pyr和萘)的阴离子自由基与三烷基氯硅烷R反应1 R 2 R 3 SiCl(R 1-3 = Me,Et; R 1,2 = Me,R 3 = t -Bu)遵循经典的双分子方案。单电子转移(ET),以一个两电子处理的比率(S Ñ 2样的氯硅烷介体的还原形式的亲核攻击,其中k 2 ≅10 2 -10 8 M -1 s -1)与Si在亲核取代反应中的空间利用率成反比。亲核取代途径主要产生单和二芳基化的芳族产物。与DFT计算相平行的电化学数据显示,由于SN亲硅溶剂(DMF)参与了硅的配位扩展,并沿反应坐标动态修改了该过程的能量,因此其在S N过程中的作用非常复杂。尽管2,2'-联吡啶也可形成离域的持久性阴离子自由基,但它们不会像芳香族介体一样引发ET和S N反应。2