Effect of para Substitution on Dissociation of N-Phenylbenzenesulfonamides

2004 ◽  
Vol 69 (7) ◽  
pp. 1479-1490 ◽  
Author(s):  
Martin Mansfeld ◽  
Patrik Pařík ◽  
Miroslav Ludwig
Keyword(s):  
Elemental Analysis ◽  
Principal Components ◽  
Latent Variables ◽  
Dissociation Constants ◽  
Additive Model ◽  
Reaction Centre ◽  
Hammett Equation ◽  
Substituted Anilines ◽  
Transmission Effect ◽  
Substituent Constants

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, pKHA, 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 σp constants and the Yukawa-Tsuno equation with σp- and σp 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.

Chemometric Analysis of Substituent Effects. VI. A Study of ortho Effect in Dissociation of 2,6-Disubstituted Benzoic Acids

1995 ◽  
Vol 60 (5) ◽  
pp. 829-840 ◽  
Author(s):  
Jiří Kulhánek ◽  
Oldřich Pytela
Keyword(s):  
Latent Variables ◽  
Dissociation Constants ◽  
Additive Model ◽  
Substituent Effects ◽  
Point Of View ◽  
Steric Effects ◽  
Benzoic Acids ◽  
Hammett Equation ◽  
Substituent Constants ◽  
Substituted Benzoic Acids

Ten 2,6-disubstituted benzoic acids have been synthesized containing all possible combinations of the following substituents: CH3, OCH3, Cl, and NO2. The dissociation constants of these acids have been measured by potentiometric titration in methanol, acetone, dimethyl sulfoxide, dimethylformamide, acetonitrile, pyridine, and 1,2-dichloroethane. The experimental data obtained together with the pK values of 2-substituted benzoic acids in the same solvents have been analyzed from the point of view of ortho effect and additivity of disubstitution. The mutual interaction between substituents was found to represent only 0.12% of the variability due to substitution and to contribute to the overall variability of data less than the interaction between the substituent and solvent by a factor of about 13. The analysis of data by the method of multiple linear regression revealed a contribution of steric effects beside the effects transmitted through the aromatic skeleton. The 2- and 6-substituents effects are additive within the validity of the Hammett equation, and an addition of a multiplicative term describing interactions between the substituents is statistically insignificant. Nonlinear regression has been adopted in the additive model with multiplicative term to find the inner substituent constants including all the effects of substituents from ortho position: the term describing the interaction between 2- and 6-substituents is statistically insignificant in this model. An application of the method of conjugated deviations revealed two statistically significant latent variables. The first one explains 91.5% of the variability of data and is connected with the substituent effects transmitted through the aromatic skeleton. The second one explains 7.5% of variability of data and predominantly reflects the steric effects of substituents.

Effects of Medium and Substituents on Dissociationof 4,4'-Disubstituted Bis(benzenesulfon)imides

1996 ◽  
Vol 61 (8) ◽  
pp. 1205-1214 ◽  
Author(s):  
Miroslav Ludwig ◽  
Pavel Štverka
Keyword(s):  
Latent Variables ◽  
Dissociation Constants ◽  
Substituent Effects ◽  
Principal Component ◽  
H Nmr ◽  
Base Process ◽  
Elemental Analyses ◽  
Substituent Constants ◽  
Model Substances ◽  
Strong Acids

Ten 4,4'-disubstituted bis(arenesulfon)imides of the general formula XC6H4SO2NHSO2C6H4X have been synthesized and their structures confirmed by their 1H NMR spectra. Elemental analyses are presented for the compounds not yet described. The dissociation constants of these model substances have been measured potentiometrically in pyridine, dimethylformamide, methanol, ethanol, propylene carbonate, acetone, acetonitrile, 1,2-dichloroethane and tetramethylene sulfone. The pKHA values obtained have been correlated with three sets of the Hammett substituent constants and the results have been used to discuss the solvent and substituent effects on the dissociation of the compounds studied. Sulfonimides with electron-acceptor substituents behave as rather strong acids in some solvents (pyridine, dimethylformamide, methanol and ethanol), whereas normal substituent dependences are found in other solvents. The experimental data have also been interpreted with the help of the statistical methods based on latent variables. From the calculations it follows that only the first principal component, which correlates well with the substituent constant sets adopted, is statistically significant in describing the substituent effect on the acid-base process studied.

A Study of Transmission Effects of Sulfonyl and Carbonyl Groups

1995 ◽  
Vol 60 (5) ◽  
pp. 841-850 ◽  
Author(s):  
Miroslav Ludwig ◽  
Patrik Pařík ◽  
Jiří Kulhánek
Keyword(s):  
Latent Variables ◽  
Dissociation Constants ◽  
Substituent Effects ◽  
Principal Component ◽  
Carbonyl Groups ◽  
H Nmr ◽  
Deviation Analysis ◽  
Substituent Constants ◽  
The Difference ◽  
Latent Structures

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 pKHA 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.

Acid-Base Properties of Substituted Naphthoic Acids in Nonaqueous Media

1997 ◽  
Vol 62 (11) ◽  
pp. 1737-1746 ◽  
Author(s):  
Patrik Pařík ◽  
Miroslav Ludwig
Keyword(s):  
Experimental Data ◽  
Linear Regression ◽  
Latent Variables ◽  
Latent Variable ◽  
Dissociation Constants ◽  
Substituent Effects ◽  
Acid Base ◽  
Nonaqueous Media ◽  
Substituent Constants ◽  
Substituted 1

Thirteen substituted 1-naphthoic acids have been prepared and their dissociation constants, along with those of twenty-five substituted 2-naphthoic acids, have been measured potentiometrically in methanol, N,N-dimethylformamide, pyridine, and acetonitrile. The pKHA values obtained have been treated by linear regression using four sets of substituent constants. The experimental data have also been interpreted by statistical methods using latent variables. The first latent variable calculated by these methods can be used as a new set of substituent constants for describing substituent effects in naphthalene skeleton.

The Hammett substituent constants and effects of medium

1986 ◽  
Vol 51 (10) ◽  
pp. 2143-2150 ◽  
Author(s):  
Oldřich Pytela ◽  
Miroslav Ludwig ◽  
Miroslav Večeřa
Keyword(s):  
Factor Analysis ◽  
Principal Components Analysis ◽  
Excellent Agreement ◽  
Principal Components ◽  
Solvent Effects ◽  
Dissociation Constants ◽  
Benzoic Acids ◽  
Substituent Constants ◽  
Components Analysis ◽  
Substituted Benzoic Acids

The dissociation constants measured earlier for 35 substituted benzoic acids in seven solvents (water, methanol, ethanol, dimethylformamide, acetonitrile, sulfolane, and acetone) have been submitted to the principal components analysis and the factor analysis to produce sets of the Hammett substituent constants. The solvent effects have been evaluated on the dissociation constants of the substituted benzoic acids and, hence, also on the respective substituent constants. He differences have been compared between the substituent constants determined by the principal components analysis and by the factor analysis, the latter being found to be more suitable. The obtained sets of substituent constants have been confronted with literature data, and an excellent agreement has been found between the σ constants derived from the measurements in water with the sets of primary substituent constants and some other sets.

Chemometrical Analysis of Substituent Effects. IV. Additivity of Substituent Effects in Dissociation of 3,5-Disubstituted Benzoic Acids in Organic Solvents

1994 ◽  
Vol 59 (7) ◽  
pp. 1637-1644 ◽  
Author(s):  
Oldřich Pytela ◽  
Jiří Kulhánek ◽  
Miroslav Ludwig
Keyword(s):  
Organic Solvents ◽  
Dissociation Constants ◽  
Quantitative Description ◽  
Substituent Effects ◽  
Benzoic Acids ◽  
Hammett Equation ◽  
Specific Solvation ◽  
Reaction Constant ◽  
Substituent Constants ◽  
The Individual

Ten 3,5-disubstituted benzoic acids have been synthesized containing all possible combinations of the following substituents: CH3O, CH3, Cl/Br, NO2. The dissociation constants of these acids have been measured in seven organic solvents (methanol, acetone, dimethyl sulfoxide, dimethylformamide, acetonitrile, pyridine, 1,2-dichloroethane). It has been found that the effect of disubstitution is smaller than that due to interaction of substituents or their solvation and represents only about 0.2% of the effect caused by the individual substituents. The additivity in 3,5-disubstitution is about 2 - 3 times as good as that in 3,4-disubstitution. The quantitative description of substituent effects at the 3 and 5 positions is additive within the range of validity of the Hammett equation irrespective of the type of the substituent constants adopted, the addition of the multiplicative term being statistically insignificant. The solvent effect on 3,4- and 3,5-disubstituted derivatives is somewhat different at the same value of the reaction constant, due predominantly to the specific solvation of the 4-CH3O and 4-NO2 groups.

Reparametrization and/or Determination of Hammett, Inductive, Mesomeric and AISE Substituent Constants for Five Substituents: N+(CH3)3, CH2N+(CH3)3, CH2Py+, CH2SO2CH3 and PO(OCH3)2

2004 ◽  
Vol 69 (12) ◽  
pp. 2239-2252 ◽  
Author(s):  
Jan Pícha ◽  
Radek Cibulka ◽  
František Liška ◽  
Patrik Pařík ◽  
Oldřich Pytela
Keyword(s):  
Nonlinear Regression ◽  
Latent Variables ◽  
Dissociation Constants ◽  
Least Square Method ◽  
Partial Least Square ◽  
Least Square ◽  
Benzoic Acid Derivatives ◽  
Correlation Models ◽  
Substituent Constants ◽  
Substituted Benzoic Acids

Ten meta- and para-substituted benzoic acids with substituents N+(CH3)3, CH2N+(CH3)3, CH2Py+, CH2SO2CH3 and PO(OCH3)2 were synthesized. Dissociation constants of these acids were determined in five solvents (water, ethanol, methanol, N,N-dimethylformamide, dimethyl sulfoxide) at 25 °C. Dissociation constants of benzoic acid derivatives with other substituents H, CH3, NHCOCH3, OCH3, F, Cl, Br, I, COCH3, CN, NO2, SO2CH3 were taken from the literature (calibration set). Substituent constants σm, σp, σI, σR, and σi for substituents N+(CH3)3, CH2N+(CH3)3, CH2Py+, CH2SO2CH3, and PO(OCH3)2 were calculated by nonlinear and PLS (partial least-square method with latent variables) calibration in three correlation models using the calibration set. Nonlinear regression appears more suitable and more universal than PLS calibration. The advantage of nonlinear regression is its independence on possibly missing data in the given solvent, evaluation of precision (standard deviation), the accessibility of necessary software, and easy calculation. However, in contrast to PLS calibration, this procedure fails in calculation of substituent constants with description of properties of substituents (substituent constants σI, σR). The obtained values of substituent constants are in good agreement with those published in the literature.

Chemometric Analysis of Substituent Effects. II. Relation Between Hammett Substituent Constants σm and σp and a New Model for Quantitative Description of Substituent Effects

1994 ◽  
Vol 59 (2) ◽  
pp. 381-390 ◽  
Author(s):  
Oldřich Pytela
Keyword(s):  
Dissociation Constants ◽  
General Relation ◽  
Quantitative Description ◽  
Substituent Effects ◽  
Data Series ◽  
Reaction Centre ◽  
Substituent Constant ◽  
New Model ◽  
Resonance Effects ◽  
Substituent Constants

The paper presents values of 25 substituent constants σi obtained by optimizing 46 data series of dissociation constants of substituted benzoic acids in various media. The constants σi fulfil the general relation between the substituent constants of the Hammett type in meta and para positions enabling the description of substituent effects from both positions at the same time by a single constant. The Hammett substituent constants are interpreted by means of the σi constants with an accuracy better than 0.03 units. In addition to it, the validity of general relationship between σp and σm was verified on a set of 56 substituents with the prediction accuracy of 0.06 units for σp, and after excluding the probably incorrectly parametrized substituents NHCOC6H5, CH3S, and F the accuracy has improved to 0.05 units (98% of interpreted variability). The given relationship has served as a basis for suggesting a new model of transfer of substituent effects to a reaction centre: the model involves both the Hammett equation and the Yukawa-Tsuno equation and explains their background. The suggested model uses generalized transmission coefficients to separately describe the transformation of a single primary substituent effect - depending on its structure - into one inductive and two resonance effects which are transmitted through two independent channels to the reaction centre and here transformed into the resulting observable effect. From the model it follows that the substituent constant σp is not a substituent constant in the true sense of the word since it involves the characteristics of skeleton and of reaction centre.

Chemometrical Analysis of Substituent Effects. V. ortho Effect

1994 ◽  
Vol 59 (9) ◽  
pp. 2005-2021 ◽  
Author(s):  
Oldřich Pytela ◽  
Josef Liška
Keyword(s):  
Dissociation Constants ◽  
Substituent Effects ◽  
Reaction Centre ◽  
Benzoic Acids ◽  
Electronic Effects ◽  
Substituent Constant ◽  
Zero Values ◽  
Substituent Constants ◽  
Substituted Benzoic Acids ◽  
Intramolecular Hydrogen

The dissociation constants of nineteen ortho substituted benzoic acids have been determined in eight organic solvents (methanol, ethanol, acetone, dimethyl sulfoxide, dimethylformamide, acetonitrile, pyridine, 1,2-dichloroethane). The correlation between the σI, σR, and υ constants were unsuccessful due to neglecting the description of intramolecular hydrogen bond effect. The method of conjugated deviations has been applied to the results obtained and to those given in literature for ortho substituted benzoic acids (the dissociation constants, the reaction with diphenyldiazomethane, 33 sets), and values of three types of substituent constants have been determined for 29 substituents. The first of these substituent constants, σoi, describes the electronic effects and was adjusted with the application of the isoparameter relation (σoi as a function of σmi) suggested in previous communications. This constant (after excluding the substituents NHCOCH3 and OCOCH3) correlates very well (R = 0.993) with the σI and σR constants. The second substituent constant, σHGi, describes the interaction of the reaction centre (the oxygen atom of carboxylate anion) with the substituent, and it has non-zero values for the substituents OH, SH, NH2, NHCH3, NHCOCH3, COOH, CONH2, and SO2NH2. The third substituent constant, σSi, describes the steric effects and is not significantly related to any of the known quantities of this type. The set given was tested together with the triad of σI, σR, and υ on the definition set and on a set extended by other 28 sets of processes with ortho substituted compounds. On the whole, the set of substituent constants suggested explains 94.6% of variability of data, whereas only 66.0% are explained with the use of σI, σR, and u constants. Moreover, the tests have shown that the σoi constant is not suitable for interpretations of processes involving direct conjugation between the reaction centre and substituent.

Synthesis and Antituberculotic Activity of Some Substituted 3-Arylamino-5-cyano-2-pyrazinecarboxamides

1995 ◽  
Vol 60 (7) ◽  
pp. 1236-1241 ◽  
Author(s):  
Martin Doležal ◽  
Jiří Hartl ◽  
Antonín Lyčka ◽  
Vladimír Buchta ◽  
Želmíra Odlerová
Keyword(s):  
Nucleophilic Substitution ◽  
Elemental Analysis ◽  
Nmr Spectra ◽  
Substituted Anilines ◽  
H Nmr

Nucleophilic substitution of 3-chloro-5-cyano-2-pyrazinecarboxamide by substituted anilines afforded substituted 3-arylamino-5-cyano-2-pyrazinecarboxamides I-X. The structures of compounds were confirmed by elemental analysis, UV, IR and 1H NMR spectra. The assessment of in vitro antimycotic and antimycobacterial activities of the compounds was carried out. The highest antituberculotic activity against M. tuberculosis in this series was shown by 3-anilino- 5-cyano-2-pyrazinecarboxamide (I), whose efficacy was the same as that of pyrazinecarboxamide.

Sign in / Sign up

Export Citation Format

Share Document