The gibbs energies of transfer of nicotinamide from water to water-ethanol mixtures and formation of the nicotinamide-silver(I) complex

The distribution coefficients of nicotinamide (NicNH₂) and solubility products of nicotinamide-silver perchlorate were determined by the distribution and solubility methods over a wide range of water-ethanol (EtOH) solvent compositions. The Gibbs energies of transfer of NicNH₂ and the AgNicNH ₂ ⁺ complex cation from water into water-ethanol mixtures were calculated. The influence of H₂O-EtOH solvent compositions on the stability of the nicotinamide-Ag⁺ complex was studied potentiometrically at a 0.25 ionic strength of the medium (NaClO₄) and 25.0 ± 0.1°C. The stability of complexes increased as the concentration of ethanol in mixtures grew. Reagent solvation contributions to complex formation equilibrium shifts were analyzed.