Rates of base-catalysed hydrolysis of substituted aryl benzoates

Twenty-seven 3- and 4-substituted aryl benzoates have been hydrolysed with sodium hydroxide in ethanol–water (6:4 v/v). The kinetic data are correlated by the Hammett equation with ρ= 1·93. Rate enhancements for para-conjugatively electron-withdrawing substituents (–M) are small, diagnostic of a transition state in which there is at most only slight fission of the aryloxy-carbon bond.