Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

Seventeen p-substituted N-phenylsulfonylbenzamides of general formulas XC₆H₄SO₂NHCOC₆H₅ and C₆H₅SO₂NHCOC₆H₄X have been synthesized and their structure has been confirmed by elemental analysis and ¹H NMR spectra. The dissociation constants of all the compounds have been measured by potentiometric titration in methanol, acetonitrile, dimethylformamide, dimethyl sulfoxide, and pyridine. The obtained pK_HA values have been correlated with three sets of Hammett substituent constants using simple or double linear regression. The solvent and substituent effects are discussed on the basis of experimental results, and the difference between the substituent effects from sulfonamide and benzamide sections is evaluated. It has been found that due to the extensive delocalization of negative charge in the conjugated base the transmission effects of carbonyl and sulfonyl groups on the transmission of substituent effect are roughly the same. The experimental data have been interpreted by the methods with latent variables: the principal component analysis (PCA), the conjugated deviation analysis (CDA), and the method of projection to latent structures (PLS). The results obtained by these procedures were similar.