Adduct formation in the extraction of zinc oxinate into various organic solvents

The extraction of zincoxinate into 10 different organic solvents was investigated. By studying the dependence of the distribution upon pH, reagent concentration, and solvent concentration (in an inert medium), the species were identified and the extraction constants estimated. Correlations between the species type and the efficiency of extraction are postulated. The species extracting into 4-methyl-2-pentanone, I-butanol, and 4-methyl-2-pentanol is ZnR₂S₂, that extracting into benzene and chloroform is ZnR₂(HR)S, that extracting into butyl and pentyl ethers is ZnR₂S, that extracting into carbon tetrachloride is ZnR₂(HR), and that extracting into hexane and cyclohexane is ZnR₂(H₂O)₂. In these formulas, R is the oxinate ion, HR is oxine, and S is the organic solvent. It is suggested that the extraction behavior can be explained by assuming a water molecule to be attached to the ZnR₂S and ZnR₂(HR) species.