Synthesis of polyamides from active N,N′‐diacylbis‐2‐benzothiazolones and diamines under mild conditions

The aminolysis of N‐benzoyl‐2‐benzothiazolone was studied in model systems and was found to give excellent yields of N‐substituted benzamides at room temperature. Solution polycondensation of new bisamides, N,N′‐adipoylbis‐2‐benzothiazolone and N,N′‐isophthaloylbis‐2‐benzothiazolone, proceeded fairly slowly with both aromatic and aliphatic diamines at room temperature to yield polyamides having inherent viscosities up to 1.5. Hexamethylphosphoramide was the best polycondensation medium among some polar aprotic solvents for the formation of high molecular weight polyamides. The high reactivity of the N‐acyl‐2‐benzothiazolones was discussed in relation to excellent leaving nature and intramolecular general base catalysis of the benzothiazolone moiety.