Outer-sphere Amidopyridyl Extractants For Zinc(Ⅱ) And Cobalt(Ⅱ) Chlorometallates

摘要

Protonated amidopyridyl ligands show high selectivity for the extraction of [CoCl_4]~(2-) or [ZnCl_4]~(2-) over chloride ion into organic media via the formation of N-H and C-H hydrogen-bond donors to the outer coordination spheres of the chlorometallates.rnExtraction of chlorometallates into organic media from acidic chloride feed solutions to achieve concentration and separation of metal values is used extensively in the extractive metallurgy of the precious metals.Stripping the precious metal chlorometallate back into a basic aqueous solution for downstream processing can be readily achieved if these complexes show high kinetic stability, and substitution of chloride ions by hydroxide or extractant molecules is slow.