Distribution of Co(II) between immiscible phases formed in water + 1-butanol system

Heterogeneous equilibria for the distribution of Co2+ between the two layers formed in water + 1-butanol (1-BuOH) system have been investigated at ambient conditions. The study (confined to only 28 °C) reveals an interesting feature of the distribution equilibrium for the system whereby Co2+ has been found to exist in both the phases as the same species namely its aqua-complex thus directly demonstrating strong selective solvation of Co2+ by the water molecules. Almost constant values of refractive indices and densities were exhibited by the two layers regardless in which ratio the component liquids were mixed together. However, relative volumes of the layers varied smoothly on gradually changing the ratio of the two liquids in the overall “solvent system”. Also the Co2+ distribution coefficient (KD) changed appreciably on going to alcohol-richer “solvent systems” but KD remained fairly constant on adding different amounts of cobalt dichloride to any given “solvent system”.