The pressure dependence of benzyl chloride solvolysis in aqueous acetone and aqueous dimethylsulfoxide

First-order rate constants for the solvolysis of benzyl chloride in a series of aqueous acetone and aqueous dimethylsulfoxide (DMSO) mixtures at 50.100 °C and at various pressures in the range 1–4083 atm are reported. Volume of activation, calculated from the rate/pressure data, is found to exhibit extremum behavior with varying solvent composition in both solvent systems. The activation volumes are dissected into their initial state and transition state contributions by determining the "instantaneous" volumes of solution of benzyl chloride in the solvent systems. The contributions of both the initial state and the transition state to the behavior of the activation volume as a function of solvent composition are discussed.