Novel optically active poly(amide-imide)s with tetrahydropyrimidinone and tetrahydro-2-thioxopyrimidine moieties by microwave-assisted polycondensation

Rapid and highly efficient synthesis of novel poly(amide-imide)s (PAIs) were achieved under microwave irradiation by using a domestic microwave oven from the polycondensation reactions of 4,4'-carbonyl-bis(phthaloyl-L-alanine) diacid chloride [N,N'-(4,4'-carbonyldiphthaloyl)] bisalanine diacid chloride (1) with six different derivatives of tetrahydropyrimidinone and tetrahydro-2-thioxopyrimidine compounds (2a-2f) in the presence of a small amount of a nonpolar organic medium that acts as a primary microwave absorber. Suitable organic media was o-cresol. The polycondensation proceeded rapidly and was almost completed within 10 min, giving a series of PAIs with inherent viscosities of about 0.25-0.45 dL/g. The resulting PAIs were obtained in high yield and are optically active and thermally stable. All of the above compounds were fully characterized by means of Fourier transform infrared spectroscopy, elemental analyses, inherent viscosity (n(inh)), solubility test, and specific rotation. Thermal properties of the PAIs were investigated using thermogravimetric analysis. (C) 2001 John Wiley &Sons, Inc.