Abstract
The acid dissociatioin constants of certain Schiff bases derived from isatin with p-substituted benzoyl hydrazines and somee amino acids of glycine, β- and α-alanine, valine, β-phenyl-α-alanine and anthranilic acid have been determined potentiometrically at different temperatures in different aquo-organic solvent mixtures (ethanol, dioxane, ddimethyl formamide, methanol, acetone and tetrahydrofurance). The pKa values were demonstrated on the light of the different electronic and steric effects of the substituents and the solvent characteristics. In all the mixed media used, ionization of the compounds decreased by increasing the mole fraction of the organic cosolvent. Theermodynamic parameters (ΔH°, ΔG°, ΔS°) were evaluated. The structural effects of the investigated compounds on these parameters were reported and discussed.
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Hassaan, A.M.A., Quenawy, M.T.A. Temperature, medium and structural effects on the acid dissociation constants of certain Schiff bases derived from isatin with some amino acids and aroylhydrazines. Arch. Pharm. Res. 16, 180–185 (1993). https://doi.org/10.1007/BF02974479
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DOI: https://doi.org/10.1007/BF02974479