ISSN:
0020-7608
Keywords:
Computational Chemistry and Molecular Modeling
;
Atomic, Molecular and Optical Physics
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
pKa(NH3+) values of N,N-dihydroxyethylglycine (bicine) and N-[tris(hydroxymethyl)methyl]-glycine (tricine) have been determined by the Irving-Rossotti method in an aqueous medium at 25, 30, 35, 40, 45, and 50°C and at different ionic strengths (I = 0.1, 0.5, and 1.0). Plots between pKa(NH3+) and 1/T for various ionic strengths have been obtained and the values of slopes have been used to calculate the ΔH, ΔS, and ΔG for the dissociation reactions of bicine and tricine. The ΔH, ΔS, and ΔG values for bicine were found to be 10.6 ± 0.6 kcal mol-1, -1.9 ± 1.8 e.u., and 11.1 ± 0.06 kcal mol-1, respectively, and for tricine 11.2 ± 0.6 kcal mol-1, 1.6 ± 1.6 e.u., and 10.7 ± 0.06 kcal mol-1, respectively. The pKa(NH3+) values decrease with rise in temperature but the influence of ionic strength is not significant.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/qua.560200211
