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.