Extraction selectivity of diphenyl(dialkylcarbamoylmethyl)phosphine oxideswith different substituents at the phosphorus atom

The effect of substituent at the nitrogen atom in diphenyl[dialkylcarbamoyl methyl]phosphine oxides (CMPOs) on their extractive power toward actinides and lanthanides and on the separation factors Am(III)/lanthanides(III), Pu( IV)/Am(III), U(VI)/Am(III), and Pu(IV)/U(VI) was studied. The nature of sub stituent at the nitrogen atom affects to a small but a different extent the distribution factors of the elements and hence their separation factors. T he highest selectivity is exhibited by the reagents with a long or branched alky) chain of the substituent at nitrogen. Introduction of octyl radicals as substituents at nitrogen increases the separation factors Pu(IV)/Am(III ) and U(VI)/Am(VI) by an order of magnitude compared to other CMPOs studied . The use of CMPOs with octyl and iso-amyl substituents at nitrogen ensures the Am/Ln separation factor greater than 2, which principally allows separ ation of trivalent actinides and lanthanides by liquid chromatography with a free stationary phase.