Synthesis and Characterization of Novel Organosoluble, Thermal Stable and Optically Active Polyesters Derived from 5-(2-Phthalimidiylpropanoylamino)isophthalic acid

A new aromatic diacid monomer containing pendent L-alaninephthalimide group was synthesized in three steps in high yield and purity. Several new, highly soluble and optically active aromatic polyesters containing phthalimide and flexible chiral groups were prepared with moderate molecular weights by direct polycondensation with tosyl chloride (TsCl), pyridine (Py) and N,N-dimethylformamide (DMF) as condensing agent. The aim of this work was to obtain novel optically active polyesters that were more soluble in common organic solvents while maintaining the high thermal stability. All polymers derived from such a diacid and aromatic diols were highly organosoluble in the solvents like N-methyl-2-pyrrolidinone,N,N-dimethylacetamide, DMF, Py and dimethyl sulfoxide. These new optically active polyesters with inherent viscosities ranging from 0.21 to 0.81 dL/g were obtained with high yields. Thermogravimetric analysis (TGA) data showed that these polyesters are thermal stable, with 10% weight loss being recorded above 370 °C. Some of the above polymers were characterized by ¹H-NMR, FT-IR, elemental analyses and specific rotation techniques.