Kinetics of hydrolysis of phenyl dichloroacetates in aqueous salt solutions

Abstract

Rate constants are reported for the hydrolysis of phenyl and p-methoxyphenyl dichloroacetate in aqueous solutions containing a range of 1 : 1 salts. The dependences of rate constants on salt are examined in terms of the corresponding dependences of activity coefficients for salts in these solutions. The importance is identified of the role of overlap between hydration cospheres of ions in solutions. Kinetic solvent isotope effects depend on salt but indicate no dramatic change in mechanism when salts are added. However, the dependences on the nature and concentration of salt for the enthalpies of activation for the hydrolysis reactions show no simple relationship with the enthalpic properties of the salt solutions.