Electro-organic reactions. Part 50.Quinodimethane chemistry. Part 1. Electrochemical generation and characterisation of p-quinodimethanes

Abstract

Quinodimethanes (QDMs) were generated cathodically from 1,4-bis(halogenomethyl)arenes, either by direct or by mediated reduction, and characterised using cyclic voltammetry in the 0.1 to 200 V s⁻¹ range. Formal redox potentials (E°) were determined, including that, at −15 °C, for the parent quinodimethane. Redox catalysis with organic mediators proved to be a convenient method for the generation of quinodimethanes from 1,4-bis(chloromethyl)arenes, either for electroanalytical study of the intermediates or for preparative purposes. The quinodimethanes electrogenerated from bis(chloromethyl)arenes in the presence of an organic mediator react to give good yields of poly(p-xylylenes) (PPXs). A copolymer, proposed to be random, is obtained by mediated co-electrolysis of 1,4-bis(chloromethyl)benzenes and 2,5-bis(chloromethyl)-1,4-dimethoxybenzene.