Electrostatic effects on ionization equilibria: Solvent dependence

1984 ◽  
Vol 49 (1) ◽  
pp. 179-189 ◽  
Author(s):  
Karel Kalfus ◽  
Zdeněk Friedl ◽  
Otto Exner
Keyword(s):  
Gas Phase ◽  
Carboxylic Acids ◽  
Dissociation Constants ◽  
Aprotic Solvents ◽  
Benzoic Acids ◽  
Cavity Model ◽  
Electrostatic Effects ◽  
Solvent Dependence ◽  
Ionization Equilibria ◽  
Substituted Benzoic Acids

Apparent dissociation constants of 3-substituted bicyclo[2,2,2]-octane-1-carboxylic acids I-III and of several substituted benzoic acids were measured in four pure solvents. The results - together with numerous literature data concerning dissociation in other solvents and in the gas phase - were compared with the prediction of the electrostatic theory. The theory fails to reproduce the essential features of the solvent dependence as it predicts generally too small effects and does not differentiate between protic and aprotic solvents. The mentioned goal cannot be achieved by any more sophisticated cavity model or by any other theory as far as it characterizes the solvent only through its bulk permittivity.

scholarly journals Analysis of the Gas Phase Acidity of Substituted Benzoic Acids Using Density Functional Concepts

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1631
Author(s):  
Jorge A. Amador-Balderas ◽  
Michael-Adán Martínez-Sánchez ◽  
Ramsés E. Ramírez ◽  
Francisco Méndez ◽  
Francisco J. Meléndez
Keyword(s):  
Gas Phase ◽  
Density Functional ◽  
Chemical Potential ◽  
Fukui Function ◽  
Ortho Position ◽  
Benzoic Acids ◽  
Functional Theory ◽  
Resonance Effects ◽  
Gas Phase Acidity ◽  
Substituted Benzoic Acids

A theoretical study of the effect of the substituent Z on the gas phase acidity of substituted benzoic acids ZC6H4COOH in terms of density functional theory descriptors (chemical potential, softness and Fukui function) is presented. The calculated gas phase ΔacidG° values obtained were close to the experimental ones reported in the literature. The good relationship between the ΔacidG° values and the electronegativity of ZC6H4COOH and its fragments, suggested a better importance of the inductive than polarizability contributions. The balance of inductive and resonance contributions of the substituent in the acidity of substituted benzoic acids showed that the highest inductive and resonance effects were for the -SO2CF3 and -NH2 substituents in the para- and ortho-position, respectively. The Fukui function confirmed that the electron-releasing substituent attached to the phenyl ring of benzoic acid decreased the acidity in the trend ortho > meta > para, and the electron-withdrawing substituent increased the acidity in the trend ortho < meta < para.

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.

Dissociation constants of substituted benzoic acids in water and in organic solvents

1986 ◽  
Vol 51 (10) ◽  
pp. 2135-2142 ◽  
Author(s):  
Miroslav Ludwig ◽  
Václav Baron ◽  
Karel Kalfus ◽  
Oldřich Pytela ◽  
Miroslav Večeřa
Keyword(s):  
Potentiometric Titration ◽  
Organic Solvents ◽  
Solvent Effects ◽  
Dissociation Constants ◽  
Point Of View ◽  
Benzoic Acids ◽  
Hammett Equation ◽  
Substituent Constant ◽  
Reaction Constant ◽  
Substituted Benzoic Acids

Potentiometric titration has been used to measure dissociation constants of 38 monosubstituted benzoic acids in water and in 6 organic solvents (methanol, ethanol, dimethylformamide, acetonitrile, sulfolane, acetone). The results have been analyzed and interpreted from the point of view of substituent and solvent effects on the dissociation of the title substrates. It has been proved that solvents affect not only the reaction constant but also the substituent constant of the Hammett equation.

Oxidative C-H Acyloxylation of Acetone with Carboxylic Acids under Iodine Catalysis

Synthesis ◽  
2020 ◽  
Author(s):  
Xiao-Yu Zhou ◽  
Xia Chen
Keyword(s):  
Carboxylic Acids ◽  
Sodium Chlorite ◽  
Benzoic Acids ◽  
Aromatic Carboxylic Acids ◽  
Substituted Benzoic Acids

Iodine catalyzed oxidative C(sp3)-H acyloxylation of acetone with carboxylic acids has been developed. The method employs an iodide as catalyst and sodium chlorite as oxidant. Substituted benzoic acids, naphthoic acids and hetero-aromatic carboxylic acids can be used, and 2-oxopropyl carboxylates are obtained with good to excellent yields.

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