By the method of thermokinetics, the saponification rate constants of ethyl benzoate have been measured: (1) at 25℃ in ethanol/water mixed solvents of different weight percentage compositions, and (2) at various temperatures when the compositions of the mixtures are 50.0wt% and 57.7wt% respectively. The activation energies, frequency factors, and three activation thermodynamic parameters have also been calculated. Solvent effect supports the suggestion that the reaction observes the mechanism of B~A~C2, with an intermediate. The negative activation entropy is an important evidence for the occurring of intermediate. The frequency factor can be explained from the point of view of activation entropy.

Key words: ACTIVATION, SOLVENT EFFECT, THERMODYNAMICS, ETHYL BENZOATE, SAPONIFICATION, THERMODYNOMICS PARAMETER