Dissociation constants of mono- and poly-substituted benzoylacetanilides

Abstract

The dissociation constants of benzoylacetanilides of general formula XC₆H₄·CO·CHZ·CO·NH·C₆H₄Y have been evaluated at 25° in aqueous solution containing <1% of organic solvent. The acidity constants of monosubstituted compounds (Y ≠ H, X = Z = H) are in agreement with the classical Hammett equation, with ρ_Y= 0·79. For the polysubstituted compounds (Y ≠ H, X ≠ H, Z = H) the equation log (K_XY/K₀)=ρ_Xρ_Y(σ_X/σ_Y+σ_Y/ρ_X) was found to hold with ρ_X= 2·5. The substituent constants for o-Cl, o-Br, o-OMe, o-NEt₂, p-SO₂C₆H₄Me, p-SO₂C₆H₄NO₂, and p-OSO₂Ph have been determined. The effect of the presence of a halogen atom in position Z is also discussed.