Microwave-induced synthesis of new optically active and soluble polyamides containing pendent 4-(2-phthalimidiylpropanoylamino)benzoylamino-groups.

An aromatic chiral diacid monomer, 5-[4-(2-phthalimidiylpropanoylamino)-benzoylamino]isophthalic acid was synthesized in five steps under conventional heating in high yield and purity. A series of soluble, thermally stable and optically active polyamides (PA)s containing pendent groups made of phthalimide, flexible L: -alanine and benzamide sequence have been successfully synthesized under microwave irradiation. Excellent yields and very short reaction time were the main characteristics of this method. The same polymerization reactions were also carried out by conventional thermal heating and the results are compared. The resulting PAs had inherent viscosity in the range of 0.50-0.79 dL g(-1). All of the these polymers are readily dissolved in various solvents such as N-methyl-2-pyrrolidinone, N,N-dimethylacetamide and N,N-dimethylformamide and showed glass-transition temperature above 200 degrees C. Thermogravimetric analysis demonstrated that the 10% weight-loss temperatures in nitrogen were 372 and 422 degrees C for selected two PAs. All of these polymers showed optical rotation which is due to successful insertion of L: -alanine in the structure of chiral diacid monomer.