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) wer e achieved under microwave irradiation by using a domestic microwave oven f rom the polycondensation reactions of 4,4'-carbonyl-bis(phthaloyl-L-alanine ) diacid chloride [N,N'-(4,4'-carbonyldiphthaloyl)] bisalanine diacid chlor ide (1) with six different derivatives of tetrahydropyrimidinone and tetrah ydro-2-thioxopyrimidine compounds (2a-2f) in the presence of a small amount of a nonpolar organic medium that acts as a primary microwave absorber. Su itable organic media was o-cresol. The polycondensation proceeded rapidly a nd was almost completed within 10 min, giving a series of PAIs with inheren t 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 s pectroscopy, elemental analyses, inherent viscosity (n(inh)), solubility te st, and specific rotation. Thermal properties of the PAIs were investigated using thermogravimetric analysis. (C) 2001 John Wiley &Sons, Inc.