In this study, stoichiometric protonation constants of L-tyrosine, L-cysteine, L-tryptophane, L-lysine, and L-histidine, and their methyl and ethyl esters in water and ethanol–water mixtures of 30, 50, and 70% ethanol (v/v), were determined potentiometrically using a combined pH electrode system calibrated as the concentration of hydrogen ion. Titrations were performed at 25∘C and the ionic strength of the medium was maintained at 0.10 mol⋅L−1 using sodium chloride. Protonation constants were calculated by using the BEST computer program. The effect of solvent composition on the protonation constants is discussed. The log10 K2 values of esters generally decreased with increasing ethanol content. However, the log10 K1 values of the esters of L-tyrosine, L-cysteine, and L-tryptophane were found to increase with increasing ethanol content in contrast those of L-lysine and L-histidine esters.
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References
S. Fiol, I. Brandariz, and M. Sasrte de Vicente, The Ionization Constants of Alanine in NaCl at 25 ∘C. Effect of the Ionic Strength Based on Three Models, Talanta 42, 797–801 (1995).
I. J. Partanen, Calculation of the First and Second Stoichiometric Dissociation Constants of Glycine in Aqueous Sodium Chloride Solutions at 298.15 K, Ber. Bunsenges. Phys. Chem. 102, 855–864 (1998).
D. L. Hughes, J. J. Bergan, and E. J. J. Grabowski, Amino Acid Chemistry in Dipolar Aprotic Solvents; Dissociation Constants and Ambident Reactivity, J. Org. Chem. 51, 2579–2585 (1986).
J. Crosby, R. Stone, and G. E. Lienhard, Mechanisms of Thiamine-catalyzed Reactions. Decarboxylation of 2-(1-carboxy-1-hydroxyethyl)-3,4-dimethylthiazolium Chloride, J. Am. Chem. Soc. 92, 2891–2900 (1970).
N. Nishi, S. Takahashi, M. Matsumoto, A. Tanaka, K. Muraya, T. Taramuku, and T. Yamaguchi, Hydrogen-bonded Cluster Formation and Hydrophobic Solute Association in Aqueous Solutions of Ethanol, J. Phys. Chem. 99, 462–468 (1995).
H. Rossotti, The Study of Ionic Equilibria (Longman, London, 1978).
A. E. Martell and M. Calvin, Chemistry of the Metal Chelate Compounds (Prentice-Hall Inc., New York, 1952).
F. C. Rossotti and H. Rossotti, The Determination of Stability Constant (McGraw–Hill Inc., New York, 1961).
R. G. Bates, Determination of pH, Theory and Practice (John Wiley and Sons, New York, 1973).
D. D. Perrin and W. Armerego, Purification of Laboratory Chemicals (Pergamon Press, Oxford, 1966).
G. Gran, Determination of the Equivalent Point in Potentiometric Titrations, Part I. Acta Chem. Scand. 4, 559–577 (1950).
G. Gran, Determination of the Equivalent Point in Potentiometric Titrations, Part II, Analyst 77, 661–671 (1952).
A. E. Martell and R. J. Motekaitis, The Determination and Use of Stability Constants (VCH, Weinheim, 1988).
M. Meloun, J. Havel, and H. Högfelt, Computation of Solution Equilibria (Wiley, New York, 1988).
E. P. Serjeant, Potentiometry and Potentiometric Titrations (Wiley, NY, 1984).
E. M. Woolley, D. G. Hukot, and L. G. Hepler, Ionization Constants for Water in Aqueous Organic Mixtures, J. Phys. Chem. 74, 3908–3913 (1970).
S. Rondinini, T. Mussini, and P. R. Mussini, Autoprotolysis Constants in Nonaqueous Solvents and Aqueous Organic-solvent Mixtures, Pure Appl. Chem. 59, 1693–1702 (1987).
R. J. Motekaitis and A. E. Martell, Program PKAS: A Novel Algorithm or the Computation of Successive Protonation Constants, Can. J. Chem. 60, 1681–1689 (1982).
R. J. Motekaitis and A. E. Martell, Best—A New Program for Rigorous Calculation of Equilibrium Parameters of Complex Multi-component Systems, Can. J. Chem. 60, 2403–2409 (1982).
R. F. Jameson and M. F. Wilson, Thermodynamics of the Interactions of Catechol with Transition Metals. Part I. Free Energy, Enthalpy, and Entropy Changes for the Ionisation of Catechol at 25,∘C. Comparison of the Temperature-coefficient Method with Direct Calorimetry, J. Chem. Soc. Dalton Trans. 2507–2610 (1972).
E. Kiliç and N. Arslan, Determination of Autoprotolysis Constants of Water-Organic Solvent Mixtures by Potentiometry. Microchim Acta, 151, 89–92 (2005).
H. A. Azab, A. M. El-Nady, S. A. El-Shatoury, and A. Hassan, Potentiometric Determination of the Dissociation Constants of l-Histidine, Proline and Tryptophane in Various Hydroorganic Media, Talanta, 41, 1255–1259 (1994).
A. Dogan, F. Köseoglu, and E. Kiliç, Studies on the Macroscopic Protonation Constants of Some α-Amino Acids in Ethanol–Water Mixtures, Anal. Biochem. 309, 75–78 (2002).
F. Apruzzese, E. Bottari, and M. R. Festa, Protonation Equilibria and Solubility of l-Cystine, Talanta 56, 459–469 (2002).
B. Nowak and Z. Pawlak, Dissociation of Some Phenols in Acetone + Water Mixtures, J. Chem. Soc., Faraday Trans. 1 78, 2693–2700 (1982).
A. A. Mohamed, F. M. Bakr, and A. K. Abd El-Fattah, Thermodynamic Studies on the Interaction Between Some Amino Acids with Some Rare Earth Metal Ions in Aqueous Solutions, Thermochim. Acta 405, 235–253 (2003).
D. V. Jahagirdar, B. Arbad, T. K. Chondhekar, and S. U. Pankanti, Thermodynamics of Transfer of Amino-Acids from Water to Ethanol–Water Mixtures, Ind. J. Chem. 28A, 366–370 (1989).
A. K. Chattopadhyay and S. C. Lahiri, Studies on the Solvation of Amino Acids in Ethanol and Water Mixtures, Electrochim. Acta27, 269–272 (1982).
P. G. Daniele, P. Amico, and G. Ostacoli, Binary and Ternary Cu(II) Complexes with Malonic Acid and Glycine in Water and Water-1-propanol Mixtures, J. Inorg. Nucl. Chem. 43, 2183–2187 (1981).
F. Köseoglu, E. Kiliç, and A. Dogan, Studies on the Protonation Constants and Solvation of α-Amino Acids in Dioxan-water Mixtures, Anal. Biochem. 277, 243–246 (2000).
A. Dogan and E. Kiliç, Potentiometric Studies on the Protonation Constants and Solvation of Some α-Amino Acid Benzyl- and t-Butyl-esters in Ethanol–Water Mixtures, Turk. J. Chem. 29, 41–47 (2005).
A. Dogan, F. Köseoglu, and E. Kiliç, The Stability Constants of Copper(II) Complexes with Some α-Amino Acids in Dioxan–Water Mixtures, Anal. Biochem. 295, 237–239 (2001).
J. T. Edsall and M. H. Blanchard, The Activity Ratio of Zwitterions and Uncharged Molecules in Ampholyte Solutions. The Dissociation Constants of Amino Acid Esters, J. Am. Chem. Soc. 55, 2337–2353 (1937).
C. De Stefano, C. Foti, A. Gianguzza, and S. Sammartano, Chemical Speciation of Amino-Acids in Electrolyte Solutions Containing Major Components of Natural Fluids, Chem. Speciation Bioavailability 7, 1–8 (1995)
A. E. Martel and R. M. Smith, Critical Stability Constants, Vol. 1, (Plenum Press, New York, 1989).
E. Bottari and M. R. Festa, On the Behaviour of Cysteine as Ligand of Cadmium(II), Talanta 4, 1705–1718 (1997).
C. L. Sharma and S. S. Narvi, Thermochemistry for the Formation of Cysteinate Complex of Rhodium(III), Thermochim. Acta 90, 1–8 (1985).
R. H. Garrett and C. M. Grisham, Biochemistry (Harcourt Brace College Publishers, USA, 1999).
S. H. Hilal, Y. Shabrawy, L. A. Carreira, and S. W. Karickhoff, Estimation of Microscopic, Zwitterionic Ionization Constants, Isoelectric Point and Molecular Speciation of Organic Compounds, Talanta 50, 827–840 (1999).
M. S. K. Niazi and J. Mollin, Dissociation Constants of Some Amino Acids and Prydinecarboxylic Acids in Ethanol–Water Mixtures, Bull. Chem. Soc. 60, 2605–2610 (1987).
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Canel, E., Gültepe, A., Doğan, A. et al. The Determination of Protonation Constants of Some Amino Acids and Their Esters by Potentiometry in Different Media. J Solution Chem 35, 5–19 (2006). https://doi.org/10.1007/s10953-006-8934-3
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DOI: https://doi.org/10.1007/s10953-006-8934-3