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.

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.

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.

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.

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.

Electronic and steric effects on the three-fold Scholl-type cycloheptatriene ring formation around a tribenzotriquinacene core

2017 ◽  
Vol 4 (5) ◽  
pp. 817-822 ◽  
Author(s):  
Ho-Wang Ip ◽  
Hak-Fun Chow ◽  
Dietmar Kuck
Keyword(s):  
Substituent Effects ◽  
Ring Formation ◽  
Steric Effects ◽  
Electronic And Steric Effects

Single and triple bay-bridging Scholl-type cyclizations of several 1,4,8-triaryl-substituted tribenzotriquinacenes are subject to pronounced electronic and steric substituent effects.

On the positional reactivity order in the sulfuric acid sulfonation of the two naphthalenesulfonic acids

1983 ◽  
Vol 61 (7) ◽  
pp. 1453-1455 ◽  
Author(s):  
Peter de Wit ◽  
Hans Cerfontain
Keyword(s):  
Sulfuric Acid ◽  
Sulfonic Acid ◽  
Steric Effects ◽  
Disulfonic Acid ◽  
Acid Mixture ◽  
Aqueous Sulfuric Acid ◽  
The Difference ◽  
Reactivity Order ◽  
Electronic And Steric Effects

The sulfonation in 98.5% H2SO4 at 25.0 °C of naphthalene-1-sulfonic acid yields 58% 1,5-, 32% 1,6-, and 10% 1,7-disulfonic acids and that of the 2-sulfonic acid 4% 1,3-, 74% 1,6-, 18% 1,7-, and 4% 2,6- + 2,7-disulfonic acids. Further sulfonation of the latter disulfonic acid mixture in 105.2% H2SO4 at 25.0 °C yields 78% 1,3,6- and 12% 1,3,5- + 1,3,7-trisulfonic acids. Reaction of naphthalene-1,5-disulfonic acid with 105.2% H2SO4 at 25 °C yields 5-sulfonaphthalene-1-sulfonic anhydride.Partial rate factors for the sulfonation of naphthalene-1- and -2-sulfonate in highly concentrated aqueous sulfuric acid (where the sulfonating entity is H2S2O7) are reported. They are discussed in terms of the difference in the reactivity of the α- and β-positions of the naphthalene skeleton and the electronic and steric effects of the sulfonate substituent already present.

Analysis of Substituent Effects in Naphthalene Skeleton

2004 ◽  
Vol 69 (12) ◽  
pp. 2297-2314
Author(s):  
Patrik Pařík ◽  
Miroslav Ludwig
Keyword(s):  
Dissociation Constants ◽  
Comprehensive Evaluation ◽  
Substituent Effects ◽  
Principal Component ◽  
Alternative Interpretation ◽  
Point Of View ◽  
Carboxylic Group ◽  
Resonance Effects ◽  
The Individual

The dissociation constants of 45 substituted 1- and 2-naphthoic acids in six organic solvents (methanol, ethanol, acetonitrile, dimethylformamide, dimethyl sulfoxide, pyridine) have been used to evaluate the substituent effects in the naphthalene skeleton. The dissociation constants data have been treated traditionally by using Dewar-Grisdale equation and the Taft DSP equation, and the alternative interpretation of substituent effects (AISE) method. Quantitative comparison of substituent effects and their transmission from different positions, combination of inductive and resonance effects from various positions, and effects of solvents are discussed. Best results are predominantly provided by the AISE. Substituent effects are stronger in the case of substituents affecting from ring of the naphthalene skeleton bearing carboxylic group than from ring not bearing carboxylic group, and there are no substantial differences between the individual positions of this ring. The contribution of resonance effects at 4α and 8β positions distinctly changes with the medium. Special quality of substituent H was found in comparison with other substituents presumably due their bulkier character. The principal component analysis (PCA) has been also applied to treat the mean dissociation constants using the single substituent property approach. The dissociation together with reactivity data for other naphthalene derivatives have been tested for comprehensive evaluation using PCA. There was found a large similarity of naphthalene reactivity data tested from the point of view of substituent effects.

Chemometrical Analysis of Substituent Effects. XIII. Comparison of Substituent Effects on Dissociation and Chemical Shift in 13C NMR Spectra of Mono- and Disubstituted Benzoic Acids

2000 ◽  
Vol 65 (1) ◽  
pp. 106-116 ◽  
Author(s):  
Jiří Kulhánek ◽  
Oldřich Pytela ◽  
Antonín Lyčka
Keyword(s):  
Chemical Shift ◽  
Latent Variable ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Principal Component ◽  
Data Matrix ◽  
Steric Effects ◽  
Benzoic Acids ◽  
Indicator Variable ◽  
Substituted Benzoic Acids

The 13C chemical shifts have been measured of the carboxyl carbon atoms for all the 2-, 3-, and 4-substituted benzoic acids with H, CH3, CH3O, F, Cl, Br, I, and NO2 substituents, as well as for all 3,4-, 3,5-, and 2,6-disubstituted benzoic acids with combinations of CH3, CH3O, Cl (or Br), NO2 substituents and for symmetrically 2,6-disubstituted derivatives with Et, EtO, PrO, i-PrO, and BuO substituents. The chemical shifts of carboxylic group carbon atoms of the 3- and 4-substituted derivatives show correlation only with the substituent constants σI. For the 2-substituted derivatives was found the dependence only on σI and on the υ constant describing steric effects (s = 0.122, R = 0.996, without the CH3 derivative which has a distinct anisotropic effect). The substituent effects on the carboxylic carbon chemical shift show additivity with 3,4-, 3,5-, and 2,6-substituents, and the 2,6-disubstituted derivatives show a linear synergic effect of substituents due obviously to the steric hindrance to resonance. Application of the principal component analysis to the data matrix involving all the combinations of mono- and disubstitution involving the above-mentioned substituents has proved an identical substituent effect from all the positions on the chemical shift described by one latent variable, steric effects and anisotropic behaviour of methyl at the 2 and 2,6 positions being predominantly described by the second latent variable (with the total explained variability of 99.5%). Comparison of substituent effects on the chemical shift of carboxylic carbon with that on the dissociation constant measured in the same solvent has confirmed the anisotropy due to ortho methyl group, the ortho halogen substituents in monosubstituted derivatives also having a different effect. The dependence of chemical shift on pKa was not very close for the derivatives studied (s = 1.005, R = 0.690). The inclusion of anisotropy of ortho alkyl group by means of an indicator variable improved the correlation (s = 0.533, R = 0.925), and omitting of 2-F, 2-Cl, 2-Br, and 2-I substituents gave a regression without deviating points (s = 0.352, R = 0.968).

Multivariate micropollutants analysis in marine waters

1995 ◽  
Vol 32 (9-10) ◽  
pp. 341-348
Author(s):  
V. Librando ◽  
G. Magazzù ◽  
A. Puglisi
Keyword(s):  
Multivariate Data Analysis ◽  
Partial Least Squares Regression ◽  
Environmental Chemistry ◽  
Sampling Site ◽  
Principal Component ◽  
Least Squares Regression ◽  
Organic Micropollutants ◽  
Suspended Material ◽  
The Difference

The monitoring of water quality today provides a great quantity of data consisting of the values of the parameters measured as a function of time. In the marine environment, and especially in the suspended material, increasing importance is being given to the presence of organic micropollutants, particularly since some are known to be carcinogenic. As the number of measured parameters increases examining the data and their consequent interpretation becomes more difficult. To overcome such difficulties, numerous chemometric techniques have been introduced in environmental chemistry, such as Multivariate Data Analysis (MVDA), Principal Component Analysis (PCA) and Partial Least Squares Regression (PLSR). The use of the first technique in this work has been applied to the interpretation of the quality of Augusta bay, by measuring the concentration of numerous organic micropollutants, together with the classical water pollution parameters, in different sites and at different times. The MVDA has highlighted the difference between various sampling sites whose data were initially thought to be similar. Furthermore, it has allowed a choice of more significant parameters for future monitoring and more suitable sampling site locations.

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