Solvent dependence of pyridine aza sigma values determined from alkaline ester hydrolysis

Abstract

The alkaline hydrolysis of a series of substituted alkyl benzoates and pyridine-carboxylates in aqueous methanol, dioxan, acetone, and DMSO solvents has been studied. Hammett correlations in all solvents are excellent and sigma values for the 2-, 3-, and 4-aza groups have been derived. These are effectively solvent independent except for a significant decrease in the σ_2N value in DMSO-containing solvents.