Polycondensation of pyridine-2,6-dicarboxylic acid with some di- and tetraamino compounds

Pyridine-2,6-dicarboxylic acid phenyl ester was condensed with 3,3′-diaminobenzidine and 3,3′,4,4′-tetraaminodiphenyl ether. Polyamides were also synthesized by condensation of the above ester with p-phenylenediamine, benzidine, 4,4′-diaminodiphenyl sulfide and 4,4′-diaminodiphenyl sulfone. These amides had higher inherent viscosities and greater thermal stability than was reported before. Model compounds of imidazoles were prepared by condensation of the same ester with o-phenylenediamine and 2,3-diaminopyridine and of polyamides by condensation with aniline and 2-aminopyridine. In the case of the polyimidazole, the completely closed ring of imidazole did not form. The ultraviolet spectra of model compounds were compared with those of the polymers. The thermogravimetric curves show that the polymers are stable up to more than 400°C under argon atmosphere. All polymers were insoluble in most organic and inorganic solvents. They dissolved only partially in DMSO and DMF. Inherent viscosity was measured for the soluble polymer fraction.