Collect. Czech. Chem. Commun. 1986, 51, 1407-1410

Cyclovoltammetric study of the homogenous keto-enol equilibrium of dihydroxyfumaric acid in acid and neutral media

Dimitra Sazou, Pantelis Karabinas and Dimitrios Jannakoudakis

Laboratory of Physical Chemistry, Department of Chemistry, University of Thessaloniki, Thessaloniki, Greece


The keto-enol equilibrium of dihydroxyfumaric acid (DHF) was investigated in acid and neutral buffer solutions by cyclic voltammetry. The keto-form decreases with increasing pH, so that in neutral region (pH = 6 - 8) the equilibrium is totally shifted to the enol-form of the acid. The thermodynamic constant, Kk, of the equilibrium: enol-DHF ⇄ keto-DHF, was estimated at different pH and temperatures. The thermodynamic parameters ΔG, ΔH, and ΔS of the above equilibrium were also determined in 0.5 M-H2SO4 solution.