Green and rapid preparation of thermally stable and highly organosoluble polyamides containing L‐phenylalanine‐9,10‐dihydro‐9,10‐ethanoanthracene‐11,12‐dicarboximido moieties

A chiral diacid monomer containing L ‐phenylalanine‐9,10‐dihydro‐9,10‐ethanoanthracene‐11,12‐dicarboximido unit was successfully synthesized in four steps and used in the preparation of a series of novel optically active polyamides by direct polycondensation with diverse aromatic diamines using 1,3‐dipropylimidazolium bromide under microwave dielectric heating. Ionic liquids (ILs) efficiently absorb microwave energy and thus are employed as solvent. By controlling the concentration of 1,3‐dipropylimidazolium bromide, reaction time and power level, high yield and moderate inherent viscosity polymers could be achieved in a very short period of time. All the resulting polymers exhibited excellent solubility in various organic solvents. The polyamides were found to have inherent viscosities in the range of 0.54–0.85 dL g^?1. These polyamides had glass‐transition temperatures (T_g) above 180°C, and a 10% weight‐loss temperatures in excess of 340°C with char yield at 800°C in nitrogen higher than 40%. A comparative study on effects exerted by microwave technique with conventional method is also presented. Copyright © 2009 John Wiley & Sons, Ltd.