BASE HYDROLYSIS OF ETHYL BENZOATE IN AN OIL-IN-WATER MICROEMULSION

The base hydrolysis of ethyl benzoate has been studied in an oil-in-water (O/W) microemulsion consisting of heptane, 1.23:1 (w/w) mixture of cetyltrimethlammonium bromide (CTABr)-1-butanol, and 1:5 (w/w) mixture of KBr-H2O solutions, and found to be slower than in the corresponding aqueous and acetone-water systems. The reaction is first order in both ester and nucleophile in all cases, and the second order rate constants (k2) in the microemulsion have been measured at a phase volume (phi) of 0.78 via traditional titration techniques. To correct for the effective nucleophile concentration, a corrected rate constant k2,phi = k2 (1 - phi), was employed. The rate inhibiting characteristics of the microemulsion are a consequence of the positioning of the substrate within the microdroplet.