Alpha-substituted oxime extractants—I Extraction of Cu(II), Ni(II), Co(II) and Fe(III) by aliphatic alpha-hydroxyoximes

Abstract

Several aliphatic α-hydroxyoximes (H 2A) not previously characterized are described. The extractability by solutions of these reagents in toluene from 1 M (Na, NH 4)NO 3 media decreases in the order Fe(III) > Cu(II) > Co(II) ∼ Ni(II). Copper complexes of the types Cu(HA) 2 and CuA are formed, the latter being polymeric in the organic phase. The nickel(II) and iron(III) complexes have the compositions Ni(HA) 2 and Fe(HA) 3 respectively. Extraction of cobalt(II) proceeds irreversibly; cobalt(III) is not extracted. The order of pH values at which different α-hydroxyoximes extract a given metal parallels the expected order of steric hindrance offered by the substituent alkyl groups to the formation of the metal complex.