Journal of Solution Chemistry

, Volume 42, Issue 2, pp 412–427 | Cite as

Protonation Equilibria of Some Selected α-Amino Acids in DMSO–Water Mixture and Their Cu(II)-Complexes

  • Ahmed A. El-Sherif
  • Mohamed M. Shoukry
  • Mohamed M. A. Abd-Elgawad


The protonation constants of some α-amino acids (glycine (Gly), l-alanine (Ala), l-valine (Val), l-serine (Ser), l-leucine (Leu) and l-isoleucine (Ile)) were studied in water and DMSO–water solution mixtures containing 30, 50 and 70 vol-% DMSO; in addition the complex formation equilibria of their copper(II) complexes were studied by potentiometric technique using a combined pH electrode system calibrated in concentration units of the hydrogen ion at 25 ± 0.1 °C under a nitrogen atmosphere, and at an ionic strength of 0.10 mol·dm−3 NaNO3. The protonation constants and the overall stability constants of copper(II) complexes were influenced by changes in solvent composition, and their variations are discussed in terms of solvent and structural properties.


Amino acids Protonation equilibria Potentiometry DMSO–water mixtures Speciation Copper(II) 



















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Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  • Ahmed A. El-Sherif
    • 1
  • Mohamed M. Shoukry
    • 1
  • Mohamed M. A. Abd-Elgawad
    • 1
  1. 1.Department of ChemistryFaculty of Science, Cairo UniversityCairoEgypt

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