Application of Methylphosphonic Acid Monoalkyl Esters to the Extraction of Some Metals

Abstract

The distribution between aqueous nitric acid and benzene was examined for methylphosphonic acid monoalkyl esters where the alkyl was a methyl, propyl, butyl, isobutyl, pentyl, 2-methylbutyl, cyclohexyl or 1,2,2-trimethylpropyl group. The extraction of complexes of these reagents with Ag, Co, Zn, Sc, Yb, Eu and Hf was also investigated. The esters do not dimerize in benzene. The pK_a and K_D values of the reagents and the corresponding extraction constants were determined. Derivatives containing five and more carbon atoms in the alkyl groups were found practically applicable to the extraction.