Solvent Effect on the Dissociation Constants of Aliphatic Carboxylic Acids

1991 ◽  
Vol 44 (8) ◽  
pp. 1077 ◽  
Author(s):  
H Bartnicka ◽  
I Bojanowska ◽  
MK Kalinowski
Keyword(s):  
Solvent Effect ◽  
Dimethyl Sulfoxide ◽  
General Formula ◽  
Carboxylic Acids ◽  
Potentiometric Titration ◽  
Dissociation Constants ◽  
Solvent Polarity ◽  
P Values ◽  
Reaction Constants ◽  
Aliphatic Carboxylic Acids

Dissociation constants of 10 aliphatic carboxylic acids, of general formula R-COOH, were measured by potentiometric titration in acetonitrile, propylene carbonate, acetone, N,N- dimethylformamide and dimethyl sulfoxide. The p* reaction constants of the Taft equation were found to depend on the solvent polarity, whereas the influence of the Lewis basicity and acidity is negligible. The p* values determined earlier in water, methanol and nitromethane also fulfil this rule.

Solvent Effect on the Hammett Reaction Constant of Substituted Benzoic Acids

1993 ◽  
Vol 46 (1) ◽  
pp. 31 ◽  
Author(s):  
H Bartnicka ◽  
I Bojanowska ◽  
MK Kalinowski
Keyword(s):  
Solvent Effect ◽  
Dimethyl Sulfoxide ◽  
Dissociation Constants ◽  
Benzoic Acids ◽  
Hammett Equation ◽  
P Values ◽  
Reaction Constant ◽  
Substituted Benzoic Acids ◽  
Reaction Constants ◽  
Solvent Acidity

Potentiometric titration has been used to measure dissociation constants of 13 monosubstituted benzoic acids in nitromethane, benzonitrile , acetonitrile , propylene carbonate, acetone, N,N-dimethylformamide, dimethyl sulfoxide, methanol and formamide. The reaction constants of the Hammett equation were found to depend on the solvent acidity and basicity expressed by the α and β parameters of Kamlet and Taft. The p values determined earlier in water and ethanol also obey this rule.

Solvent effect in dissociation of substituted benzenesulphonamides in dimethylformamide, dimethyl sulphoxide, and acetonitrile

1984 ◽  
Vol 49 (11) ◽  
pp. 2593-2601 ◽  
Author(s):  
Miroslav Ludwig ◽  
Oldřich Pytela ◽  
Miroslav Večeřa
Keyword(s):  
Factor Analysis ◽  
Solvent Effect ◽  
General Formula ◽  
Potentiometric Titration ◽  
Dissociation Constants ◽  
Dimethyl Sulphoxide ◽  
Short Cycle ◽  
Testing Method

Dissociation constants of fifteen substituted arenesulphonamides of general formula XC6H4.SO2NH2 (or X2C6H3SO2NH2) have been measured by potentiometric titration in dimethylformamide, dimethyl sulphoxide, and acetonitrile. The Hammett substitution correlations have been calculated and interpreted for these media. The pKHA values measured and the results published earlier for methanol, ethanol, and water have been treated by multiple linear regresion using the published set of the parameters characterizing solvents and by factor analysis using the short cycle and the target testing method.

Solvent effects on dissociation of substituted benzenesulphonamides in acetone, 1,2-dichloroethane, tetramethylene sulphone, pyridine and some aqueous organic solvent mixtures

1986 ◽  
Vol 51 (9) ◽  
pp. 1948-1957 ◽  
Author(s):  
Miroslav Ludwig ◽  
Oldřich Pytela ◽  
Miroslav Večeřa
Keyword(s):  
Organic Solvent ◽  
General Formula ◽  
Potentiometric Titration ◽  
Solvent Effects ◽  
Dissociation Constants ◽  
Dimethyl Sulphoxide ◽  
Organic Component ◽  
Solvent Mixtures

The potentiometric titration has been used to measure dissociation constants of fifteen substituted arenesulphonamides of general formula XC6H4SO2NH2 (or X2C6H3SO2NH2) in acetone, 1,2-dichloroethane, tetramethylene sulphone, pyridine, and mixtures water-ethanol (25, 50, 75, 90% by vol. of the organic component), water-dimethylformamide (25, 50, 75% by vol.), water-acetone (25% by vol.), and water-2-methoxyethanol (80% by wt.). The results are compared with those published earlier for water, methanol, ethanol, dimethylformamide, dimethyl sulphoxide, and acetonitrile.

Conductimetric and potentiometric investigation of effect of acidity on formation of homoconjugates in acetonitrile solvent

1990 ◽  
Vol 68 (5) ◽  
pp. 674-678 ◽  
Author(s):  
Turgut Gündüz ◽  
Esma Kiliç ◽  
Güleren Özkan ◽  
Muhammed F. Awaad ◽  
Mustafa Tastekin
Keyword(s):  
Carboxylic Acids ◽  
Potentiometric Titration ◽  
Major Part ◽  
Nitrogen Atmosphere ◽  
Nonaqueous Media ◽  
Potentiometric Titrations ◽  
End Point ◽  
Titration Curves ◽  
Aliphatic Carboxylic Acids ◽  
Conjugate Base

In the present work, 11 aromatic and nine aliphatic carboxylic acids, namely benzoic, 2-nitrobenzoic, 3-nitrobenzoic, 4-nitrobenzoic, 2,4-dinitrobenzoic, 3,5-dinitrobenzoic, 2-aminobenzoic, 3-aminobenzoic, 4-aminobenzoic, o-phthalic, salicylic, formic, acetic, monochloroacetic, dichloroacetic, trichloroacetic, propionic, n-butyric, caprylic, and myristic acids, were titrated conductimetrically and potentiometrically with triethylamine in acetonitrile solvent, under a nitrogen atmosphere, at 25 °C. Closer investigation of the conductimetric titration curves of these acids showed that the acidity of an acid, rather than the basicity of its conjugate base, plays a major part in the formation of homoconjugate ions, at least in acetonitrile solvent. If the acid is strong enough, there is a maximum before the experimental end point at about the half-neutralization point. To determine the minimum strength for an acid to show this maximum before the end point, all acids were also titrated potentiometrically. It was found that those acids which have half-neutralization potentials over −85 mV give a strong homoconjugation reaction and show a maximum before the experimental end point. Moreover, the acids that show maxima before the experimental end point in the conductimetric titration also show rather well-shaped potentiometric titration curves. Keywords: nonaqueous media, conductimetric titrations, potentiometric titrations, titration in acetonitrile, acidity and homoconjugation.

Solute–solvent effects in the dissociation of thymolsulfonephthalein (an uncharged acid) in aqueous mixtures of acetonitrile (ACN), urea, and dimethyl sulfoxide (DMSO)

1986 ◽  
Vol 64 (8) ◽  
pp. 1521-1526 ◽  
Author(s):  
A. L. De ◽  
A. K. Atta
Keyword(s):  
Solvent Effect ◽  
Dimethyl Sulfoxide ◽  
Solvent Effects ◽  
Mixed Solvent ◽  
Dissociation Constants ◽  
Aqueous Mixtures ◽  
Solvent Interactions ◽  
Gibbs Energies ◽  
Gibbs Energies Of Transfer ◽  
Solvent Systems

The thermodynamic first dissociation constants, [Formula: see text] of thymolsulfonephthalein (H2A), an uncharged acid, have been determined at 25 °C in aqueous mixtures of 10, 30, 50, 70, and 80 wt% acetonitrile (ACN), 11.52, 20.31, 29.64, and 36.83 wt% urea, 20, 40, 60, and 80 wt% dimethyl sulfoxide (DMSO) by spectrophotometric measurements. The solvent effect represented by ∂(ΔG0) = 2.303RT[p(sK)N − p(wK)N] is found to increase in ACN + H2O system as mol% ACN increases in the solvent. In contrast, the corresponding values in urea + H2O as well as DMSO + H2O solvent systems decrease with increase in proportion of organic component in the solvent, the decrease being sharp in urea + H2O. The results have been discussed in terms of the standard Gibbs energies of transfer of H+ from water to the mixed solvent, [Formula: see text] and the relative values of the standard Gibbs energies of transfer of HA−, [Formula: see text] and of [Formula: see text] in all the solvent systems. The overall dissociation behaviour of the acid (H2A) is found to be dictated by the specific solute-solvent interactions of the species participating in the dissociation equilibria.

Dissociation of substituted benzenesulphonamides in water, methanol and ethanol

1984 ◽  
Vol 49 (5) ◽  
pp. 1182-1192 ◽  
Author(s):  
Miroslav Ludwig ◽  
Oldřich Pytela ◽  
Karel Kalfus ◽  
Miroslav Večeřa
Keyword(s):  
Linear Regression ◽  
Multiple Linear Regression ◽  
Potentiometric Titration ◽  
Principal Components ◽  
Dissociation Constants ◽  
Benzoic Acids ◽  
Reaction Constant ◽  
The Media ◽  
Reaction Constants

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.

A Simple Method of Calculating Dissociation Constants of Carboxylic Acids and Phenols in Various Solvents

1979 ◽  
Vol 32 (11) ◽  
pp. 2561 ◽  
Author(s):  
B Poh
Keyword(s):  
Carboxylic Acids ◽  
Dissociation Constants ◽  
P Value ◽  
Hammett Equation ◽  
Simple Method ◽  
P Values ◽  
Related Series

The Hammett equation correlating the dissociation constants (K for the substituted acid and K0 for the unsubstituted acid) of members of a closely related series of acids is given by log(K/K0) = pσ. Previously, it has been shown that the p values in other solvents can be calculated from the p value in water. In this work it is shown that the pK0 values in other solvents can also be calculated from the pK0 value in water. Therefore, we can now calculate the pK values in various solvents.

Empirical method for consideration of solvent effect on the dissociation constants of carboxylic acids

2008 ◽  
Vol 44 (1) ◽  
pp. 52-61 ◽  
Author(s):  
Yu. E. Zevatskii ◽  
D. V. Samoilov
Keyword(s):  
Solvent Effect ◽  
Carboxylic Acids ◽  
Dissociation Constants ◽  
Empirical Method
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