Rates and activation parameters of alkaline hydrolysis of the 2-carbomethoxypropionate ion in aqueous mixtures of dimethyl sulphoxide

Abstract

The rates of alkaline hydrolysis of the 2-carbomethoxypropionate ion (R^–) have been measured at 15, 25 and 35 °C in water and aqueous dimethyl sulphoxide (DMSO) mixtures of six compositions with mole fractions of DMSO varying from 0.05 to 0.40. The activation parameters have been calculated for the reaction in all these media. The thermodynamic quantities for the transfer of the reacting ion R^– have been obtained from the solubilities of the silver salt (AgR) in the media at different temperatures, using the reported transfer properties of Ag⁺. Utilising these values for the R^– ion as well as the reported values for the OH^– ion (the other reactant), together with the activation parameters for the reaction, the thermodynamic quantities for the transfer of the transition state have been calculated. Attempts have been made to correlate the kinetic results with thermodynamic parameters, and to compare the results with those for neutral ethyl acetate.