Preparation of New Poly(amide-imide)s with Chiral Architectures via Direct Polyamidation Reaction

N-trimellitylimido-l-methionine (3) was prepared by reaction of trimellitic anhydride (1) with -l-methionine (2) in acetic acid solution at refluxing temperature. This diacid was reacted with thionyl chloride, and N-trimellitylimido-l-methionine diacid chloride (4) was obtained in quantitative yield. The resulting diacid chloride was reacted with p-aminobenzoic acid in dry acetone and bis(p-aminobenzoic acid)-N-trimellitylimido-l-methionine (5) was obtained as a novel optically active amide–imide diacid monomer in high yield. The direct polycondensation of amide–imide diacid monomer 5 with several aromatic diamines was carried out with tosyl chloride (TsCl)/pyridine (Py)/dimetheylformamide (DMF) system. The resulting thermally stable poly(amide–imide)s (PAIs) were obtained in good yields and inherent viscosities ranging between 0.24 and 0.46 dL g⁻¹ and were characterized with FTIR, ¹H NMR, CHN, and TGA techniques.