Facile Synthesis of Novel Optically Active Poly(amide-imide)s Derived from N,N-(Pyromellitoyl)-bis-

Seven new optically active poly(amide-imide)s (3a-g) were synthesized by microwave assisted polycondensation of N,N´-(pyromellitoyl)-bis-l-alanine diacid chloride (1) with seven different derivatives of tetrahydropyrimidinone and tetrahydro- 2-thioxopyrimidine compounds (2a-g) by using a domestic microwave oven. The polycondensation reactions were carried out in the presence of a small amount of a polar organic medium that acts as a primary microwave absorber. Suitable organic media was o-cresol. The polycondensation proceeded rapidly, compared with the conventional melt polycondensation and solution polycondensation and it was almost completed within 10 min giving a series of poly(amide-imide)s (3a-g) with inherent viscosities about 0.22- 0.42 dL/g. The resulting poly(amide-imide)s were obtained in high yield and were optically active and thermally stable. All of the above compounds were fully characterized by means of FTIR spectroscopy, elemental analysis, inherent viscosity (ηinh), solubilities test, and specific rotation. Thermal properties of the poly(amide-imide)s were investigated using thermal gravimetric analysis (TGA).