Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

The reaction of substituted anilines and benzenesulfonyl chlorides has been used to prepare 49 substituted N-phenylbenzenesulfonamides of general formula 4-X-C₆H₄SO₂NHC₆H₄-Y-4'. Their purity was checked by elemental analysis. The substituents X and Y include H, CH₃, CH₃O, Cl, Br, CN, and NO₂. The dissociation constants of all compounds were determined by potentiometric titration in methanol, acetonitrile, N,N-dimethylformamide, and pyridine. The obtained dissociation constants, pK_HA, were correlated with various sets of substituent constants. It was found that the effects of substituents X and Y on the dissociation are best described by using the Hammett equation with σ_p constants and the Yukawa-Tsuno equation with σ_p^- and σ_p constants, respectively. This result confirms the direct conjugation of Y substituent with the reaction centre. The explained variability using the additive model was above 96% in all the solvents used. The data also provided information about the transmission effect of the SO₂ group. The average dissociation constants were further processed by the latent variables methods, principal components and conjugated deviations analyses.

Keywords: Sulfonamides; Dissociation constant; Substituent effects; Transmission effect; Chemometrics; Acidity; Hammett equation.

References: 19 live references.