Aminophosphonic acid mono-esters as reagents for solvent extraction of metals

Abstract

N-substituted mono-esters of α-aminophosphonic acid have been examined as complexing agents for the extraction of metal from solutions. It was established that N-alkyl substituted derivatives did not form salts or complexes with metals because of a strong betaine like structure. On the contrary, N-aryl substituted derivatives exhibited well pronounced extractive properties. The examination of easy accessible mono-esters of α-anilinobenzylphosphonic acid showed that octyl α-anilinobenzylphosphonate dissolved in ligroin can be successfully used for extraction of manganese, cobalt, nickel, iron, antimony, bismuth and uranium from aqueous sulphuric acid solutions. The conditions are described in which a separation of manganese from cobalt or nickel, as well as a separation of antimony (or bismuth) from arsenic is quantitatively achieved. Some extractable metal complexes with ethyl- or octyl α-anilinobenzylphosphonic acid have been identified spectrophotometrically or isolated and determined by chemical analysis.