Novel optically active poly(amide–imide)s from N, N′-(4,4 ′-carbonyldiphthaloyl)-bis- l-phenylalanine diacid chloride and aromatic diamines by microwave irradiation

Abstract

3,3 ′,4,4 ′-benzophenonetetracarboxylic dianhydride (4,4 ′-carbonyldiphthalic anhydride) ( 1) was reacted with l-phenylalanine ( 2) in a mixture of acetic acid and pyridine (3:2) and the resulting imide-acid [ N, N ′-(4,4 ′-carbonyldiphthaloyl)-bis- l-phenylalanine diacid] ( 4) was obtained in high yield. The compound ( 4) was converted to the N, N ′-(4,4 ′-carbonyldiphthaloyl)-bis- l-phenylalanine diacid chloride ( 5) by reaction with thionyl chloride. A new facile and rapid polycondensation reaction of this diacid chloride ( 5) with several aromatic diamines such as 4,4 ′-diaminodiphenyl methane ( 6a), 2,4-diaminotoluene ( 6b), 4,4 ′-sulfonyldianiline ( 6c), p-phenylenediamine ( 6d), 4,4 ′-diaminodiphenylether ( 6e), m-phenylenediamine ( 6f), benzidine ( 6g) and 2,6-diaminopyridine ( 6h) 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 was completed within 7 min, producing a series of optically active poly(amide–imide)s with high yield and inherent viscosity of 0.22–0.52 dl/g. All of the above polymers were fully characterized by IR, elemental analyses and specific rotation. Some structural characterization and physical properties of this optically active poly(amide–imide)s are reported.