An isochoric probe of the role of solvent structure in the kinetics of neutral hydrolysis of two 1-acyl-1,2,4-triazoles in aqueous solution

Abstract

Kinetic data for the neutral hydrolysis in aqueous solutions of 1 -acetyl-1,2,4-triazole and 1-benzoyl-3-phenyl-1,2,4-triazole have been analysed to yield the dependences of rate constants on temperature under isobaric and isochoric conditions. The latter condition requires that the pressure changes to hold the molar volume of water constant and equal to that at 298.15 K and 101 325 N m^–2. The contrasts in the dependence of rate constants probes the role of solvent in the activation process. In these two cases, the rate constants increase with increase in temperature more rapidly under isochoric than isobaric conditions, a trend consistent with a decrease in hydrophobic character on activation, and production of labile water molecules resulting from disruption of water–water interactions.