Self‐condensation reaction of aromatic tetraamines in polyphosphoric acid

Abstract

AbstractLadder and partial ladder polymers have been obtained by self‐condensation reactions of 1,2,4,5‐tetraaminobenzene, 3,3′,4,4′‐tetraaminodiphenyl ether, 3,3′‐diaminobenzidine and 3,3′,4,4′‐tetraaminodiphenyl sulfone in polyphosphoric acid. The products thus obtained are highly colored compounds with good thermal stability. They seem to be made up of polyquinoxaline or dihydrophenazine or a mixture of these two recurring units. They are slightly soluble in methanesulfonic acid and concentrated sulfuric acid and have inherent viscosities in the 0.2 to 0.4 range.