Effect of mixed H2O−CH3CN solvent on intramolecular general base-catalyzed cleavage of ionized phenyl salicylate in the presence of DL-proline

Abstract

Nucleophilic second-order rate constant (kn ms) for the reaction of DL-proline with ionized phenyl salicylate (PS-) shows a nonlinear decrease with the increase in the content of CH3CN in mixed aqueous solvents at _< 50 % v/v CH3CN. The values of kn ms show a mild increase with the increase in the content of CH3CN at > 50 % v/v CHaCN. The effect of solvent on kn ms is explained in terms of solvent effect on the pKa of the conjugate acids of leaving group ( i.e. phenolate ion) and DL-proline.