Hammett Substituent Effect on the Cleavage Rate Constants of Anion Radicals in Dimethylformamide

Abstract

The substituent effect on the cleavage rate constants of anion radicals for a series of aryl bromides and α-phenoxyacetophenones is described by the Hammett equation; the opposite signs of the reaction constants are explained on the basis of the thermodynamic contribution to the activation barrier, mainly the difference in the formal potentials of a parent molecule and a leaving anion.