Preparation and characterization of optically active polyamides based on 3-phenyl-2-(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)propanoyl-amino in 1,3-dipropylimidazolium bromide

Abstract

The exploitation of ionic liquids (IL)s for the preparation and use of non-vinyl macromolecules brings together two of the most stimulating and promising areas of research from recent years. In this study, IL, 1,3-dipropylimidazolium bromide, was examined as a replacement for volatile toxic organic solvents for the direct polycondensation of chiral dicarboxylic acid monomer, 5-[3-phenyl-2-(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)propanoylamino]isophthalic acid (1) with diverse aromatic diamines (2a–2g). The optically active polyamides (PA)s were obtained in 80–98% yield and the inherent viscosities in the range of 0.39–0.69 dLg⁻¹. The higher inherent viscosities and thermal stability were found in this IL compared to analogous compounds in organic solvents under milder reaction conditions. The yields of the PAs were comparable. All the polymers were amorphous and exhibited excellent solubility in many organic solvents. The procedure was found to be an efficient and green technique for the synthesis of the aforementioned PAs. The PAs were characterized by FTIR, specific rotation, ¹H NMR, elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry and X-ray diffraction.