Synthesis of optically active poly(amide-imide)s derived from N,N′-(4,4′-carbonyldiphthaloyl)-bis-L-leucine diacid chloride and aromatic diamines by microwave radiation

3,3',4,4'-benzophenonetetracarboxylic dianhydride (4,4'-carbonyldiphathalic anhydride) was reacted with L-leucine in a mixture of acetic acid and pyridine (3 : 2), and the re suiting imide-acid [N,N'-(4,4'-carbonyldiphthaloyl)-bis-L-leucine diacid] was obtained in quantitative yield. The compound was converted to the N,N'-(4,4'-carbonyldiphthaloyl)-bis-L-leucine diacid chloride by reaction with thionyl chloride. A new facile and rapid polycondensation reaction of this diacid chloride with several aromatic diamines such as 4,4'-diaminodiphenyl methane, 2,4-diaminotoluene, 4,4'-sulfonyldianiline, p-phenylenedi-amine, 4,4'-diaminodiphenylether, and m-phenylenediamine was developed by using a domestic microwave oven in the presence of a small amount of a polar organic medium such as O-cresol. The polymerization reactions proceeded rapidly compared with the conventional solution polycondensation and were completed within 6 min, producing a series of optically active poly(amide-imide)s with a high yield and an inherent viscosity of 0.37-0.57 dL/g. All of the above polymers were fully characterized by IR, elemental analyses, and specific rotation. Some structural characterization and physical properties of these optically active poly(amide-imide)s are reported. (C) 2000 John Wiley & Sons, Inc.