The acid dissociation constants of the benzimidazole-2-carboxaldoxime have been determinedpH-metrically in different proportions of aqueous methanol, ethanol, isopropanol, acetone and dioxane. The influence of ionic strength, temperature and solvent on the acid dissociation equilibria of −OH and$$ - \mathop N\limits^ + H$$ = groups has been studied. A comparison of ΔH and ΔS terms in different aquo-organic media reveals that the positive ΔS is probably the main driving force in the acid dissociation processes of these groups. The effect of solvent was discussed in the light of dielectric constants, solvent basicity, hydrogen bonding and solute solvent interactions that operate in various aquo-organic media.
