Estimation of acid dissociation constants from potentiometric titration curves

1977 ◽  
Vol 8 (2) ◽  
pp. 127-136
Author(s):  
John A. Farrington
Keyword(s):  
Potentiometric Titration ◽  
Dissociation Constants ◽  
Acid Dissociation ◽  
Acid Dissociation Constants ◽  
Titration Curves

Solution speciation in the aqueous Na(I)–EDTA and K(I)–EDTA systems

1993 ◽  
Vol 71 (5) ◽  
pp. 763-768 ◽  
Author(s):  
Min Chen ◽  
R. Stephen Reid
Keyword(s):  
Potentiometric Titration ◽  
Ethylenediaminetetraacetic Acid ◽  
Dissociation Constants ◽  
Equilibrium Constants ◽  
Acid Dissociation ◽  
Equilibrium Models ◽  
Acid Dissociation Constants ◽  
Aqueous Sodium ◽  
Ph Values ◽  
Solution Speciation

Speciation in the aqueous sodium(I) – ethylenediaminetetraacetic acid and potassium(I) – ethylenediaminetetraacetic acid equilibrium systems was investigated by automated gravimetric potentiometric titration. It was found that in both cases, particularly below neutral pH values, speciation includes a previously uncharacterized diprotonated complex. All formation and acid dissociation constants were measured for the full systems. The validity of previous literature equilibrium constants, which are based on incomplete equilibrium models, is discussed.

Nuclear magnetic resonance studies of the acid–base chemistry of amino acids and peptides. III. Determination of the microscopic and macroscopic acid dissociation constants of α,ω-diaminocarboxylic acids

1976 ◽  
Vol 54 (21) ◽  
pp. 3392-3400 ◽  
Author(s):  
Thomas L. Sayer ◽  
Dallas L. Rabenstein
Keyword(s):  
Chemical Shift ◽  
Dissociation Constants ◽  
Nonlinear Least Squares ◽  
Acid Dissociation ◽  
Acid Base ◽  
Acid Dissociation Constants ◽  
Ammonium Group ◽  
Titration Curves ◽  
Chemical Shift Titration ◽  
The Difference

The acid–base chemistry of 2,3-diaminopropionic acid (dap), 2,4-diaminobutyric acid (dab), ornithine (orn), and lysine (lys) has been studied by 13C and proton nmr spectroscopy. Macroscopic acid dissociation constants for titration of the two ammonium groups of each molecule have been calculated from the 13C chemical shift titration curves for the alkyl carbon atoms by nonlinear least squares curve fitting methods. Microscopic acid dissociation constants for the simultaneous titration of the two ammonium groups of protonated orn and lys have been obtained from their proton chemical shift titration curves and from the 13C titration curves for orn and dap. The results indicate that the α-ammonium group of each of these α,ω-diaminocarboxylic acids is more acidic than its ω-ammonium group, but that the difference decreases as the number of carbons separating the ammonium groups decreases so that the acidities of the two ammonium groups of dap are almost identical. Results of pmr studies of the acid–base chemistry of glycyl-L-lysine and L-lysylglycine also are reported.

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