Activation parameter changes as an additive tool for a mechanistic viewpoint in the aromatic nucleophilic substitution reactions in solution

Abstract

A study was made of the influence of the substituent effects on the activation parameters changes in the SNAr reactions. It involved the analysis of both the free energy of activation ∆G ≠ from the reaction rate constants at single temperature and δ∆G ≠ reaction constants obtained by the Hammett-like equation. The analysis of the internal enthalpy constants δ∆H int ≠ and the Hammett ρ constants allowed one to prove the existence of dependence between the δ∆H int ≠ and ρ values in which the high magnitudes of these constants indicate a change in the mechanism from a polar SNAr pathway to a SET (single electron transfer).