Alkyl Halide Hydrolysis in Aqueous Alcohol-Water Mixtures. Correlation between Activation Parameters and Partial Molal Quantities of the Solvent

摘要

A method has been devised to correlate observed changes in the enthalpy of activation of alkyl halide hydrolyses in alcohol-water solutions with partial molar thermodynamic quantities of the solvent components. The partial molar quantities in the past have been related to structural changes in the alcohol-water mixtures. Thus, this correlation can be used to deduce specific solvation changes taking place in the transition state of alkyl halide hydrolysis in alcohol-water solutions. It was generally observed that groups of the solvating alcohol species have to be removed in the transition state with the number of alcohol molecules removed increasing as the alkyl group grows larger. Water molecules participate in the formation of the transition states of substrates containing primary or secondary carbon centers but do not participate in the transition state of tertiary carbon centers.