AbstractThe ratiok1/k2of the alkaline saponification coefficients for the methyl and ethyl esters of the symmetrical aliphatic dicarboxylic acids, seems to be controled only by a statistical factor 2 and by the effect of the ionic centre in the mono‐ester anion, the hydrolysis of which is characterized byk2.In accordance with the electron repelling effect of the tert. butyl group, a deviating value fork1/k2in the case of the tert butyl esters was expected. We have studied these esters and compared the data with those of the corresponding methyl and ethyl esters. The latter esters were measured by Ingold in aqueous solution. Since the ditert butyl esters are insoluble in water, they had to be saponified in dioxane‐water mixtures.The kinetic salt and medium effects, which arise upon saponifying the neutral esters and the mono‐ester anions, were studied.A method for findingk2, free of salt effects, is indicated. Furthermore a method is described by which one can deducek1for the neutral esters in water from the constants in dioxane‐water m