Use of convolutive potential sweep voltammetry in the calculation of hydration equilibrium constants of α-dicarbonyl compounds

The applicability of the convolution potential sweep voltammetry to the calculation of hydration equilibrium constants K_H for a series of α-dicarbonyl compounds is demonstrated. K_H values for glyoxal, methylglyoxal, acetylbenzoyl, 1,2-cyclohexanedione, diacetyl and 3,4-hexanedione are obtained as functions of the temperature. The values of apparent ΔH and ΔS are calculated from these constants. The consistency of the K_H values is tested by showing the occurrence of an enthalpy—entropy compensation effect. Hydration reactions are shown to be enthalpy controlled.