Description of Solvent Dependence of Rate Constants in Terms of Pairwise Group Gibbs Function Interaction Parameters. Medium Effects for Hydrolysis of p-Methoxyphenyl Dichloroacetate in Aqueous Solutions Containing Urea and Alkyl-Substituted Ureas

Article abstract of DOI:10.1021/j100307a041

Rate constants for neutral hydrolysis of p-methoxyphenyl dichloroacetate in aqueous solutions are sensitive to the molarity of added urea and alkyl-substituted ureas.These dependences are considered in the light of pairwise Gibbs function parameters describing interaction between solutes in aqueous solutions.In the next stage these interactions are examined by using the Savage-Wood additivity principle for pairwise group interaction parameters involving organic solutes and both initial and transition states for the hydrolysis reaction.The basis of the approach is described showing how kinetic and thermodynamic data are drawn together and used to comment on mechanisms of reaction in aqueous solutions.For the hydrolysis of the dichloroacetate ester, we account for the observed dependence of rate constant on solvent in terms of a reaction that is second order with respect to water, where the transition state exposes three OH groups to the aqueous solution, and in terms of derived group interaction parameters involving these OH groups and both CH2 and CONH groups in added solutes.