Protonation equilibria of amides and related compounds. Part III. σ and σ+ Correlations in some N-substituted benzamides

Abstract

The protonation equilibria in aqueous sulphuric acid of eight ring-substituted N-(2,2,2-trifluoroethyl)benzamides and eight similarly substituted N-ethylbenzamides, have been studied. The basicities of the former set are correlated best by σ⁺, and of the latter by σ, substituent constants. The amides studied follow the acidity function, H_A, reasonably well, so that no separate acidity function for secondary amides is required.