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.

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.

Ortho Effect in Dissociation of Substituted N-Phenylbenzenesulfonamides

2001 ◽  
Vol 66 (9) ◽  
pp. 1380-1392 ◽  
Author(s):  
Jiří Nádvorník ◽  
Miroslav Ludwig
Keyword(s):  
Experimental Data ◽  
Latent Variables ◽  
Dissociation Constants ◽  
Substituent Effects ◽  
Principal Component ◽  
Steric Effects ◽  
Deviation Analysis ◽  
Acid Base Equilibrium ◽  
The Difference ◽  
Electronic And Steric Effects

Twenty-five 2,2'-disubstituted N-phenylbenzenesulfonamides (2-X-C6H4SO2NHC6H4-Y-2') were synthesised and their purity checked by elemental analysis. This set of model substrates involved all possible combinations of methoxy, methyl, hydrogen, chloro, and nitro substituents. The dissociation constants of the sulfonamides were determined by potentiometric titration in methanol, pyridine, dimethyl sulfoxide, N,N-dimethylformamide, acetone, and acetonitrile. The dissociation constants pKHA obtained were correlated with various sets of substituent constants describing electronic and steric effects of the substituents, and the statistically treated data were used to discuss the contribution of the substituent effects in the dissociation and the difference between the effects transmitted from the two rings. A linear regression model explaining 99% of the variability of experimental data in all the solvents has been found and discussed. Moreover, the experimental data were also interpreted by the methods using latent variables, the principal component analysis (PCA) and conjugated deviation analysis (CDA), and two latent variables were shown to be statistically significant in the description of dissociation. The first obviously describes common action of electronic and steric effects of substituents; the other probably concerns a combined effect of substituent and solvent on the position of acid-base equilibrium.

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.

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.

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.

Chemometrical analysis of substituent effects on 13C and 15N NMR chemical shifts in 1-aroyl-3-substituted thioureas

1989 ◽  
Vol 54 (9) ◽  
pp. 2399-2407 ◽  
Author(s):  
Oldřich Pytela ◽  
Josef Jirman ◽  
Antonín Lyčka
Keyword(s):  
Latent Variables ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
The Other ◽  
15N Nmr ◽  
Nmr Chemical Shifts ◽  
Additional Constant ◽  
Substituent Constants ◽  
Derivatives Of ◽  
C Nmr

The methods of conjugated deviations and regression analysis have been used to study the substituent effects on 13C and 15N NMR chemical shifts of 12 derivatives of 1-aroyl-3-phenylthiourea and 1-aroyl-3-methylthiourea. The 13C NMR chemical shifts can be described by two latent variables, one univocally correlated with the Hammett substituent constants (r = 0.993) and the other reflecting the increased shielding of the nuclei due to overlap of the adjacent bond electrons as a consequence of electron-donor or electron-acceptor character of the substituents.This effect is less pronounced with the 15N nuclei. Application of dual substituent constants σR, σF with the additional constant σα describing the polarization has failed in giving sufficiently close correlations and explanation of the substituent effect found.

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.

scholarly journals Infrared and 13C NMR Spectral Studies of some Aryl Hydrazides: Assessment of Substituent Effects

2014 ◽  
Vol 32 ◽  
pp. 88-94 ◽  
Author(s):  
Ganesamoorthy Thirunarayanan ◽  
K.G. Sekar ◽  
R. Lakshmi Narayanan
Keyword(s):  
Regression Analysis ◽  
Statistical Analysis ◽  
Linear Regression ◽  
Linear Regression Analysis ◽  
Substituent Effects ◽  
Spectral Studies ◽  
Substituent Constants ◽  
Multi Linear Regression ◽  
Spectral Group ◽  
C Nmr

A series of some aryl hydrazides have been synthesized. These hydrazides purities were analyzed by physical constants and spectral data. The assigned spectral group frequencies were correlated with Hammett substituent constants and Swain-Lupton parameters using single and multi-linear regression analysis. From the results of statistical analysis, the effect of substituents on the spectral group frequencies has been discussed

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