An NMR study on polycondensation reactions of 3,5-diamino-1,2,4-triazole with dianhydrides and diacyl chlorides

The reactivity of 3.5-1H-diamino-1,2,4-triazole (DAT) in condensation reactions with acetic anhydride, aromatic dianhydrides and diacyl chlorides was investigated. In comparison to ordinary aromatic diamines, the primary amino groups of DAT were found to have relatively low reactivities so that they are partially involved in the reactions. In contrast, the secondary amino group of DAT was determined to he so reactive that it is always involved completely in the reactions. The reactivities of the amino groups in DAT were found to decrease in the order =NH(1) much greater than-NH2(3) much greater than-NH2(5). The low reactivity of the primary amino groups in DAT might be attributed to the relatively high electronegativity of the heterocyclic five-membered nitrogens, the imino characteristics of the primary amino groups via tautomerization, and the amidization of the reactive secondary amino group and the resultant steric hinderance. Because of the limited reactivities, polymers with high molecular weight could not be synthesized from DAT with diacyl chlorides and dianhydrides.