Hydantoin and thiohydantoin derivatives 4(a-e) were synthesized from reactions of
benzil and benzil derivatives 3(a-e) with urea and thiourea. 5,5-dimethylhydantoin
4f was synthesized from the reactions of acetone cyanohydrin 3f and ammonium
carbonate. Benzil and benzil derivatives 3(a-e) were obtained from oxidation of benzoin
and benzoin derivatives 2(a-e) with concentrated nitric acid. Benzoin and benzoin
derivatives were obtained from benzoin condensation of benzaldehyde and benzaldehyde
derivatives. Hydantoin and thiohydantoin derivatives 4(a-e) were characterized by
melting points, elemental analysis, FTIR, 1H NMR and 13C NMR spectroscopy. The
polycondensation reactions of 4,4-carbonyl-bis(phthaloyl-L-alanine) diacid chloride 5 with
six different derivatives of hydantoin and thiohydantoin compounds 4(a-f) were carried
out in DMAc solution in the presence of pyridine. The resulting poly(amide-imide)s, PAIs,
6(a-f) with inherent viscosities about 0.15-0.38 dL/g were obtained in high yield and were
optically active and thermally stable. All of the above compounds were fully characterized
by means of FTIR spectroscopy, elemental analysis, inherent viscosity (ηinh),
solubility test and specific rotation. Thermal properties of the PAIs 6(a-f) were
investigated using thermal gravimetric analysis (TGA).