Synthesis and polymerizations of nitrile substituted quinodimethanes

Abstract

The spontaneous polymerization behavior of an acceptor substituted quinodimethane was investigated. High molecular weight homopolymers of 7,8,-di(ethoxycarbonyl)-7,8-dicyanoquinodimethane (DEDCQ) or copolymers of DEDCQ-styrene (St) and DEDCQ-p-methoxystyrene (p-MeOSt) were formed spontaneously in chloroform containing acetic acid. All polymerizations occurred by a radical mechanism. High molecular weight polymers formed at low conversion. Radical homopolymerization of DEDCQ was promoted by ambient light or heat. DEDCQ-p-MeOSt copolymerizations yielded alternating copolymers, which formed rapidly relative to the DEDCQ homopolymers and copolymers (rich in styrene). All of these polymerizations are thought to begin with a bond forming mechanism and propagate by polyaddition. A new acceptor group substituted quinodimethane was synthesized, characterized and copolymerized with electron donating monomers. Oxidation of the dianion of α, α'-dicyano-α, α'-diphenyl-p-xylene yielded 45% 7,8-dicyano-7,8-diphenylquinodimethane. In solution this compound exists in both the trans and cis forms but forms a sharply melting crystalline solid. It was resistant to homopolymerization but did form low molecular weight copolymers with electron rich aromatic monomers.