The alkaline hydrolysis of ethyl salicylate has been studied a t 35°C within the [OH1 range of 0.001-2.00 M. The observed hydroxide ion concentration dependence of rate has been explained by proposing the occurrence of two parallel kinetic steps shown as in the rate law: rate
[Es] where ES represents ionized ethyl salicylate. The value of k l is ca. lo6 times larger than the expected value of rate constant for uncatalyzed aqueous cleavage of ethyl-p-hydroxybenzoate. This rate advantage is attributed to intramolecular general base catalysis. The analysis of observed activation parameters indicates that ca. lo6 times rate enhancement is entirely due to favorable entropy change. The Brgnsted-type plots show an extremely low sensitivity of rate constants K 1 and k 2 with respective Brgnsted coefficient of / 3; , = -0.03 ? 0.01 and & = -0.01 2 0.05, on the basicity of leaving groups of salicylate esters (alkoxide and phenoxide ions). The low values of these Br0nsted coefficients indicate essentially little or an insignificant amount of bond cleavage between carbonyl carbon and leaving group in the rate-determining step in both the k , and k 2 steps. The rate constants obtained a t different ethanol concentration follow Grunwald-Winstein m Y equation with m = 0.14 ? 0.01.