Synthesis of poly(aryl ether phenylquinoxaline) via Ullmann ether condensation of chlorine-substituted A-B quinoxaline monomers

An improved, less expensive route to a high-performance poly(aryl ether phenylquinoxaline) has been developed. Thus, an isomeric mixture of self-polymerizable (A-B) quinoxaline monomers, 2-(4-hydroxyphenyl)-3-phenyl-6-chloroquinoxaline and 3-(4-hydroxyphenyl)-2-phenyl-6-chloroquinoxaline, was prepared by the condensation of 1,2-diamino-4-chlorobenzene with 4-hydroxybenzil. The mixture was polymerized at 200°C in benzophenone containing potassium carbonate and a freshly prepared copper(I)chloride/quinoline catalyst mixture. The polymer obtained displayed an intrinsic viscosity of 1.53 dl/g (m-cresol at 30.0±0.1°C) and a glass transition temperature of 252°C (DSC), similar to samples prepared previously from an analogous fluorine-substituted mixture.