Alkaline hydrolysis of glycol esters - A newly suggested criterion in the assessment of anchimeric assistance

Abstract

Solvent effects vis a vis structural effects on the alkaline hydrolysis of various di-and mono-benzoates of glycols have been studied in binary solvent mixtures of dimethyl sulphoxide-water, ethanol-water and acetone-water. It is observed that the higher the stabilization of the transition state by the neighbouring group, the greater is the susceptibility of the reaction to dipolar aprotic solvent acceleration[i.e. k(Me2SO)/k(EtOH) value]. The possibility of employing such solvent effects to evaluate the extent of anchimeric assistance in ester hydrolysis where the neighbouring group can stabilize the transition state is examined. The studies have been extended to triethylene glycol derivatives and it is suggested that dipolar aprotic-protic solvent effects could be used as a kinetic probe for the conformation of the molecule.