Kinetics of Acid-Catalysed Hydrolysis of Diethylsuccinate in Dioxane-Water Mixtures

The specific rate constants k and k of the consecutive first-order acid-catalysed hydrolysis steps of diethylsuccinate in dioxane-water mixtures covering the range 0-95% (w/w) of dioxane are determined at 25-55 °C. As the concentration of dioxane increases, the rate of the reaction decreases to a minimum at about 90% (w/w) dioxane, after which it increases again. The ratio k1/k2 was found to be almost constant at the value 2.0. The activation energies of the reaction are independent of solvent composition. Available electrostatic theories regarding the effect of the dielectric constant on the rate are presented, from which the reaction is shown to be an ion-molecular dipole type of interaction. The thermodynamic parameters and the radii of the activated complex at different solvent compositions are calculated and discussed.