Abstract
A direct method for the determination of the pK a values of acids conjugated to substituted pyridine N-oxides has been proposed which is based on the pH measurement of the solution of the basic salt. It has been experimentally shown that the method is reliable when applied to N-oxides of not too low basicity (pK a >5). Correlation has been performed between the pK a values in aqueous and aprotic media solutions which shows the great influence of the solvation effect on the acid-base equilibria. The good correlation between the pK a values in aqueous and non-aqueous solutions enables the pK a values in water to be estimated with sufficient accuracy, even in the cases when the experimental limitations make the determination impossible which is shown on the basis of selected examples.
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References
H. H. Jaffe,J. Am. Chem. Soc. 77, 4445 (1955).
J. N. Gardner and A. R. Katritzky,J. Am. Chem. Soc. 4375 (1957).
C. Klotufar, F. Krasovec, and M. Kusar,Croat. Chim. Acta 40, 23 (1968).
B. A. Korolev, K. A. Osmolovskaya, and K. M. Dumaev,Zh. Obschch. Khim. 49, 898 (1977).
L. Chmurzyński, A. Wawrzynów, and Z. Pawlak,Electrochim. Acta 35, 665 (1990).
L. Chmurzyński, A. Wawrzynów, and Z. Pawlak,J. Chem. Soc. Faraday Trans. I 85, 4269 (1989).
L. Chmurzyński,Pol. J. Chem. (in press).
A. Liwo, K. Sokolowski, A. Wawrzynów, and L. Chmurzyński,J. Solution Chem. 19, 1113 (1990).
M. Jaskólski, M. Gdaniec, and Z. Kosturkiewicz,Pol. J. Chem. 56, 297 (1982).
D. Hadži,J. Chem. Soc. 5128 (1962).
M. Szafran,Pol. J. Chem. 53, 2491 (1979).
M. Szafran and Z. Dega-Szafran,J. Mol. Struct. 99, 189 (1983).
L. Chmurzyński, Z. Pawlak, and H. Myszka,Pol. J. Chem. 59, 639 (1985).
L. Chmurzyński, A. Liwo, A. Wawrzynów, and A. Tempczyk,J. Mol. Struct. 143, 375 (1986).
A. Wawrzynów, K. Sokolowski, L. Chmurzyński, and A. Liwo,J. Mol. Struct. 174, 235 (1986).
I. M. Kolthoff and M. K. Chantooni, Jr.,J. Am. Chem. Soc. 87, 4428 (1965).
L. Chmurzyński,J. Chem. Thermodyn. (submitted).
J. Kostrowicki and A. Liwo,Comput. Chem. 8, 91 and 101 (1984).
J. Kostrowicki and A. Liwo,Comput. Chem. 11, 195 (1987).
L. Chmurzyński, Z. Pawlak, and H. Myszka,J. Mol. Struct. 80, 235 (1982).
L. Chmurzyński, Ph.D. Thesis, University of Gdańsk (1986).
J. F. Coetzee, G. P. Cunningham, D. K. McGuire, and G. R. Padmanabhan,Anal. Chem. 32, 1139 (1962).
R. A. Abramovich and E. M. Smith,Pyridine and its Derivatives (Wiley, New York, 1974).
D. D. Perrin,Dissociation Constants of Organic Bases in Aqueous Solutions (Butterworths, London 1965).
J. J. Christensen, L. D. Hansen, and R. M. Izatt,Handbook of Proton Ionization Heats and Related Thermodynamic Quantities (Brigham Young University, Provo, Utah, 1976).
L. Chmurzyński,J. Chem. Soc. Faraday Trans I (in press).
A. Wawrzynów, Ph.D. Thesis, University of Gdańsk (1985).
L. Chmurzyński, A. Liwo, and A. Tempczyk,Z. Naturforsch. 44b, 1263 (1989).
H. L. Friedmann,Pure Appl. Chem. 53, 1277 (1981).
E. M. Kosower,J. Chim. Phys. Phys.-Chim. Biol. 61, 230 (1964).
M.-C. Justice and J.-C. Justice,J. Solution Chem. 5, 543 (1976);6, 819 (1977).
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Chmurzyński, L., Liwo, A. Simple methods for the estimation of ionization constants of substituted pyridine N-oxides in polar aprotic solvents and water. J Solution Chem 20, 731–738 (1991). https://doi.org/10.1007/BF00650719
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DOI: https://doi.org/10.1007/BF00650719