Kinetic and Thermodynamic Study of the Acid-Catalysed Hydrolysis of Diethylmalonate in Dioxane-Water Mixtures

Abstract

A kinetic study of the acid-hydrolysis of diethylmalonate in water and dioxane-water mixtures covering the range 0-95% (w/w) of dioxane is reported. The reaction rate is inversely proportional to the organic content of the medium up to about 80% (w/w) then, after passing through a minimum, it becomes directly proportional as the dioxane cosolvent is further added. The kinetic ratio k1/k2 is independent of the solvent composition. The observed activation energies, thermodynamic parameters and radii of the activated complexes along the whole range of solvent composition, for the two consecutive steps of the reaction, are computed. Electrostatic theories favour an interaction in which an ion and a molecular dipole are involved. Application of the reactivity-selectivity principle (RSP) to the present reaction in comparison with that for diethylsuccinate. under different conditions of temperature and solvent composition, is presented.