Polycondensation reaction of N',N'-(4,4′-oxydiphthaloyl)-bis-L-isoleucine diacid chloride with aromatic diamines

4,4'-Oxydiphthalic anhydride (1) was reacted with L-isoleucine (2) in acetic acid and the resulting imide-acid (3) was obtained in high yield. The diacid chloride 4 was obtained from diacid derivative (3) by reaction with excess thionyl chloride. The polycondensation reaction of diacid chloride 4 with several aromatic diamines such as 4,4'-sulphonyldianiline (5a), 4,4'-diaminodiphenyl methane (5b), 4,4'-diaminodiphenylether (5c), p-phenylenediamine (5d), m-phenylenediamine (5e), and 4,4'-diaminobiphenyl (5f) was accomplished by two conventional methods: low temperature solution polycondensation and short period reflux conditions. In order to evaluate conventional solution polycondensation reaction methods with microwave-assisted polycondensation, the reactions were also carried out under microwave conditions in the presence of small amount of o-cresol that acts as a primary microwave absorber. The reaction mixture was irradiated for 6 min with 100% of radiation power. A series of new optically active poly(amide-imide)s (PAIs) with inherent viscosity ranging from 0.22-0.44 dL/g has been prepared with high yield. All of the above polymers were fully characterized by FTIR, elemental analyses and specific rotation techniques.