scholarly journals Effect of Temperature and Solvent Composition on the Acid Dissociation Constants of 2-Pyrrol and 2-Thiophene Aldehyde Phenyl Sulphonyl Hydrazones

2016 ◽  
Vol 08 (10) ◽  
pp. 442-449
Author(s):  
Refaat I. Nessim ◽  
Imad E. Albalaa ◽  
Mona Abu Assi
Keyword(s):  
Dissociation Constants ◽  
Solvent Composition ◽  
Acid Dissociation ◽  
Effect Of Temperature ◽  
Acid Dissociation Constants

Re-examination of the Kirkwood–Westheimer theory of electrostatic effects. III. Dissociation constants of cis-3- and trans-4-substituted cyclohexanecarboxylic acids in water–dimethyl sulfoxide mixtures

1978 ◽  
Vol 56 (8) ◽  
pp. 1130-1133 ◽  
Author(s):  
Jitka Kirchnerova ◽  
Patrick G. Farrell ◽  
John T. Edward ◽  
Jean-Claude Halle ◽  
Robert Schaal
Keyword(s):  
Dimethyl Sulfoxide ◽  
Dissociation Constant ◽  
Dissociation Constants ◽  
Solvent Composition ◽  
Potentiometric Method ◽  
Acid Dissociation ◽  
Electrostatic Effects ◽  
Acid Dissociation Constants ◽  
Cyclohexanecarboxylic Acid

Acid dissociation constants of two cis-3- and of four trans-4-substituted cyclohexanecarboxylic acids in water – dimethyl sulfoxide mixtures of varying composition were determined by a potentiometric method. Results have been analyzed according to the model of Kirkwood and Westheimer, and shown to differ from calculated values because of certain oversimplifications built into the model. Dissociation constant differences between cyclohexanecarboxylic acid and the compounds studied vary only slightly with changing solvent composition.

scholarly journals The equilibrium constant of the phosphoglyceromutase reaction

1974 ◽  
Vol 139 (3) ◽  
pp. 491-497 ◽  
Author(s):  
John B. Clarke ◽  
Michael Birch ◽  
Hubert G. Britton
Keyword(s):  
Ionic Strength ◽  
Equilibrium Constant ◽  
Dissociation Constants ◽  
Ph Dependence ◽  
Binding Constants ◽  
Acid Dissociation ◽  
Effect Of Temperature ◽  
Acid Dissociation Constants ◽  
The Difference ◽  
Low Ionic Strength

The equilibrium constant of the phosphoglyceromutase reaction was determined over a range of pH (5.4–7.9), in solutions of different ionic strength (0.06–0.3) and in the presence of Mg2+, at 30°C and at 20°C. The values obtained (8.65–11.65) differ substantially from previously published values. The third acid dissociation constants were redetermined for 2- and 3-phosphoglycerate, and in contrast with previous reports the pK values (7.03 and 6.97 respectively at zero ionic strength) were closely similar. The Mg2+-binding constants were measured spectrophotometrically and the values, 286mm-1 and 255mm-1 for 2- and 3-phosphoglycerate at pH7 and ionic strength 0.02, were also very similar. From the relative lack of effect of temperature, pH and ionic strength it is concluded that the equilibrium constant differs from unity largely because of entropic factors. At low ionic strength, in the neutral region, the pH-dependence can be attributed to the small difference in the acid dissociation constants, but the difference in dissociation constants does not explain the pH-dependence in the acid region or at high ionic strength. Within physiological ranges of pH, Mg2+ concentration and ionic strength there will be little variation in equilibrium constant.

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