Dissociation of substituted benzenesulphonamides in water, methanol and ethanol

Abstract

Thirteen monosubstituted arylsulphonamides (XC6H4SO2NH2) and two 3,4-disubstituted arylsulphonamides (X2C6H3SO2NH2) have been synthetized and their dissociation constants have been measured by potentiometric titration in water, methanol, and ethanol. The Hammett substitution dependences have been calculated for all the media, and changes in the reaction constants due to transition from water to alcohols are discussed in confrontation with analogous dependences of benzoic acids. The reaction constant ρ found in methanol is lower than that in water. The dissociation constants have been treated mathematically by the method of the principal components and by multiple linear regression.

Structure-Reactivity-Spectra Correlations for Substituted Benzenesulfonamides

“…From the infrared spectral data of the investigated compounds only the wavenumbers of the asymmetric SO 2 vibration, n as ðSO 2 Þ and the arithmetic mean of the symmetric and asymmetric NH 2 stretching vibrations, nðNH 2 Þ were found to correlate with the dissociation constants, the Hammett substituent constants, the PM3 S¼ ¼O bond orders and the oxygen atom charge densities; Eqs. (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). This is in accordance with a previous observation [13] that for several organic compounds containing SO 2 groups only the wavenumbers of the n as ðSO 2 Þ but not for the, n s ðSO 2 Þ vibration correlate satisfactorily with the s substituent constants.…”

“…However, there is no systematic investigation of substituent effects on these chemical shifts. The most systematic approach to the study of substituent effects on both IR and NMR spectral data of substituted benzenesulfonamides can be found in the paper of De Benedetti et al [1] Recently, dissociation constants of substituted benzenesulfonamides in various solvents have been measured and treated by the Hammett equation [10][11][12]. The dissociation constants determined in three selected solvents were taken as a measure of the acidity of the benzenesulfonamide system and used in our further investigation.…”

Effect of para Substitution on Dissociation of N-Phenylbenzenesulfonamides

“…The dissociation constants of all the substances at 25°C in methanol (MeOH), acetonitrile (AN), N,N-dimethylformamide (DMF), and pyridine (Py) were determined by potentiometric titrations using TITRALAB 3 automatic titrator (Radiometer). The method of measurement and the electrode arrangement used were the same as in our previous paper 10 . Each measurement was repeated three to five times.…”

Ionization constants of all seven positional isomers of quinolinesulfonamides and quinoline-N,N-dimethylsulfonamides

“…pK a values of sulfonamides were determined both by potentiometric titrations [21][22][23][24] and also by UV-spectroscopic analysis [30]. But for quinolines UV-spectroscopic determination were applied most often [49,50].…”

“…Determination of acidity constants could be performed with the experimental procedures based on potentiometric titration [20][21][22][23][24][25][26][27], spectroscopic determination (UV-VIS [20,25,26,[28][29][30][31][32], NMR [33,34] and even EPR [35]), chromatography (RP HPLC [36][37][38][39]) and capillary electrophoresis [25,[40][41][42][43][44][45][46][47][48]. pK a values of sulfonamides were determined both by potentiometric titrations [21][22][23][24] and also by UV-spectroscopic analysis [30].…”