Soluble New Optically Active Polyamides Derived from 5-(4-Methyl-2-phthalimidylpentanoylamino)isophthalic acid and Different Diisocyanates Under Microwave Irradiation in Molten Ionic Liquid

Ionic liquids (IL)s have been generating increasing attention over the last decade. ILs were orginally introduced as alternative green reaction media owing to (heir distinctive chemical and physical properties of nonvolatility, nonflammability, thermal stability, and controlled miscibility. In this investigation, 5-(4-methyl-2-phthalimidyl-pentanoylamino)isophthalic acid (6), as a bulky monomer, containing phthalimide and flexible chiral groups, has been synthesized. The direct polycondensation of this diacid monomer with several aromatic and aliphatic diisocyanates, Such as 4,4'-methylenebis(phenyl isocyanate), toluylene-2,4-diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate, was carried out in tetrabutylammonium bromide as a molten IL in the presence of different catalysts under microwave irradiation as well as conventional heating. The resulting polyamides (PA)s were characterized by FTIR and H-1 NMR spectroscopy, inherent viscosity measurements, thermal and elemental analysis. The obtained PAs showed high yields and moderate inherent viscosities in a ran-e of 0.32-0.57 dL g(-1). The PAs were soluble in aprotic polar solvents. Thermogravimetric analysis showed that PAs are thermally stable, 10%, weight lobs temperatures in excess of 240 and 245 degrees C, and char yields at 600 degrees C in nitrogen higher than 14%, Since toxic and volatile solvent Such as NMP was eliminated, this process was safe and green. It is very important to note that, because of high polarizability of ILs, they are very good solvents for absorbing microwaves. The combination of IL and microwave irradiation leads to large reductions in reaction times, very high heating rate with various benefits of the eco-friendly approach, named green chemistry. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 112: 244-253, 2009