Reaction kinetics of the reaction of terephthalic acid and ethylene carbonates

Abstract

AbstractThe kinetics of the reaction of terephthalic acid with a number of ethylene carbonates in the presence of an amine catalyst were examined. All reactions apparently follow first‐order kinetics; therefore, the solution rate of TPA is not rate‐limiting. With minor adjustments, the mechanism appears to be in accord with that of the model reaction of benzoic acid and ethylene carbonate previously reported. Attack of the carboxylate on the carbonate ring must be the rate‐limiting step. Substituent effects (owing to substituents on the carbonate ring) appear to be mostly steric in nature; surprisingly, an n‐octyl group causes the slowest reaction. Besides being strongly influenced by steric hinderance, the transition state appears to be highly polar. Activation energy (16.0 kcal/mol) and activation entropy (−23.6 cal/deg) are very similar to those of the model reaction.