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We describe here the full synthesis of a novel family of bifunctional ligands and present a complete study of their extraction properties in regards to an aqueous phosphoric acid solution containing uranium. We developed a high yielding synthesis of amido phosphonate ligands and focused our investigation on the effect of steric hindrance on the methylene bridge between the two functions. These new bifunctional ligands were found to extract selectively hexavalent uranium U(VI) with high distribution coefficient (D) and selectivity towards iron Fe (III) in 5 M phosphoric acid solution. From a structure-activity approach a specific ligand called DEHCNPB has been put forward in regard to the outstanding results obtained for the selective extraction, and quantitative recovery of uranium compared to the URPHOS reference system. [ABSTRACT FROM PUBLISHER]

Ligand systems containing amido-phosphonic acid moieties were synthesized for subsequent U(VI) extraction from phosphoric acid solutions. Studies have shown that the efficiency of extraction (distribution ratios and selectivity of U(VI) over Fe(III)) is influenced by the nature of the N-dialkyl substituents and the length and nature of the spacer. A structure-activity approach resulted in the identification of a specific ligand called DEHCBPA that exhibited larger D-values than the corresponding URPHOS reference system. The distribution ratios for U(VI) extraction increased considerably with a branched N-dialkyl chain when a steric hindrance was introduced into the methylene bridge of the amido-phosphonic acid ligands. [ABSTRACT FROM AUTHOR]