Nucleophilic and general base catalysis by pyridine and methylpyridines in the hydrolysis of aryl acetates

Abstract

Pyridine bases catalyse the hydrolysis of aryl acetates and activation parameters for several of these reactions have been determined. The size of the kinetic isotope effect indicates nucleophilic catalysis. Substitution at the 2-position in pyridine prevents nucleophilic catalysis, but a much slower general base catalysed pathway was detected and it is argued that this occurs even when nucleophilic catalysis appears to be the mechanism. Anion desolvation may be important in the reaction with hydroxide ion with aryl esters.