Esterification of maleic acid with ethanol over cation-exchange resin catalysts

Diethyl maleate is an important intermediate extensively used in the production of latex emulsion polymers, thermoplast and thermoset plastics. The current paper delineates the efficacy of several heterogeneous catalysts, such as Indion-170, Amberlyst-36, Amberlyst-15, Amberlite IRA 120, 20% DTP/K-10 (dodecatungstophosphoric acid supported on K-10 clay) in the esterification of maleic acid with ethanol at reflux, Amongst these Indion-170, Amberlyst-36, Amberlyst-15 were observed to be the most effective. It was observed that the catalyst chosen has excellent reusability and was not deactivated. The effects of various parameters on the rate of reaction demonstrated that the reaction was intrinsically kinetically controlled and there were no intraparticle and interparticle mass transfer limitations. A pseudo-homogeneous kinetic model was developed from the experimental data and activation energy was found to be 14.2 kcal/mol. which also suggested that this reaction was intrinsically kinetically controlled. (C) 2002 Elsevier Science B.V. All rights reserved.