MECHANISM AND KINETICS OF THE COCL2-CATALYZED ESTERIFICATION REACTIONOF CASTOR-OIL WITH OLEIC-ACID

The apparent orders of the Lewis acid-catalyzed esterification reactio ns between castor oil and oleic acid are known to change with the cata lyst used and with the reaction temperature. A mechanism is proposed i n this study to explain the variations (with temperature) in the appar ent orders oi the cobalt chloride-catalyzed esterification reaction be tween castor oil and oleic acid. According to the proposed mechanism, an acid-catalyst intermediate forms in an initial, fast quasi-equilibr ium step, and this intermediate then reacts with the oil to yield the products and to regenerate the catalyst in the rate-determining second step. A general rate expression, with an acid concentration term and a temperature-dependent constant in the denominator, is derived from t he proposed mechanism and is verified with data obtained at different temperatures.