STUDIES ON THE FORMATION OF PEN .1. KINETIC ASPECTS OF CATALYZED REACTION IN TRANSESTERIFICATION OF DIMETHYLNAPHTHALATE WITH ETHYLENE-GLYCOL

The transesterification of dimethyl naphthalate (DMN) with ethylene gl ycol (EG) was kinetically investigated in the presence of various cata lysts at 185-degrees-C. The transesterification was assumed to obey fi rst-order kinetics with respect to DMN and EG, and a rate equation was derived. The rate constant of transesterification which was calculate d from the quantity of methanol which distilled from the reaction vess el was used to evaluate the activity of each metal compound. The first -order dependence on the catalyst concentration is valid below a criti cal concentration which was found to be dependent on the catalyst type . The order of decreasing catalytic activity of various metal ions was found to be: Pb greater-than-or-equal-to Zn > Co > Mg > Ni greater-th an-or-equal-to Sb, but in the case of highly basic metal salts, the ra te constants were found to be extremely large at the initial stage of the reaction, and then rapidly decreased with the progress of the reac tion. Effects of reaction temperature were also discussed. The activat ion energies for zinc acetate and lead acetate were 97.84 and 108.8 kJ /mol, respectively, which were calculated from the Arrhenius equation. (C) 1994 John Wiley & Sons, Inc.