Extraction of copper(II) from acid chloride solutions by N-dodecyl- and N,N-dihexylpyridinecarboxamides

N-dodecyl- and N,N-dihexylpyridinecarboxamides with amide group at 2, 3 or 4 position were synthesized. Model individual amides were used to recover c opper(II) from chloride solutions at constant water activity and constant t otal concentration of dissolved species in aqueous solution. It was found t hat pyridine-2-carboxamide forms with copper complexes (CuCl2)(x)(Ext)(2). Remaining amides form with copper complexes CuCl2(Ext)(2). Monoallcylamides are not suitable for extraction because they and their complexes are sligh tly soluble in the hydrocarbon diluents. N,N-dialkylpyridinecarboxamides an d their copper complexes are sufficiently soluble in the hydrocarbon phase to carry our extraction. However, they are strong extractants and extract e fficiently copper already from dilute chloride solutions ([Cl-] = 0.1 M). T hey extract also significant amounts of copper from concentrated (3 - 4 M) nitrate solutions.