Polyquinoxalines

The reaction of stoichiometric amounts of 1,4‐diglyoxalylbenzene with 3,3′‐diaminobenzidine affords nearly quantitative yields of a polyquinoxaline. Reaction of the monomers in the absence of solvent and heating to 250°C. or reaction of the monomers in a solvent to form a prepolymer and heating of the prepolymer to 250°C. provides soluble polymer with nearly identical properties. Heating the polymer to 375°C. under reduced pressure increase the molecular weight. A study of model compounds and reactions indicates that the polymer is predominately poly[2,2′‐(1,4‐phenylene)‐6,6′‐diquinoxaline] instead of the 2,3′‐ or 3,3′‐isomers. These polymers are stable in air to 500°C. and under nitrogen lose only 20% of their weight at 800°C.