INTERACTION AND ACTIVATION IN AQUEOUS MIXTURES

The properties of aqueous solutions are considered from the standpoint of solute-water and solute-solute interactions. In both cases, we stress the important role played by water-water interactions in aqueous solutions. Solute-solute interactions in dilute aqueous solutions are described using pairwise interaction parameters. We comment on procedures which express these parameters in terms of group interaction parameters. With an increase in the amount of solute, strong evidence is obtained for clustering of both aqueous and non-aqueous components. Aqueous mixtures also provide convenient reaction media with quite diverse properties which, in some cases, accelerate and, in other cases, inhibit the rates of chemical reactions. In this paper we indicate how these trends can be understood in terms of preferential salvation of initial and transition states using Kirkwood-Buff integral functions. The analysis is applied to kinetic data describing the dependence on the ethanol mole fraction of the first order rate constant for the solvolysis of t-butyl chloride in aqueous solution. © 1990.