Derivatives of (2-Carbamoylethyl)diphenylphosphine Oxides: Synthesis and Extraction Properties toward Actinides and Lanthanides

A series of (2-carbamoylethyl)diphenylphosphine oxides (CEPO) has been synthesized from commercially available reagents: chlorodiphenylphosphine and acrylamides. Effect of coordinating fragments Ph₂P(O)(CH₂)₂C(O), nature of oligoyl group that binds these fragments, and the presence of additional coordinating centers in CEPO on extraction properties toward actinides and lanthanides has been studied. It has been found that N,N′-methylene-bis[3-(diphenylphosphoryl)propionamide] (III) containing two diphenylphosphorylpropionyl fragments bound by rigid HNCH₂NH linker shows the highest efficiency in extraction of actinides (recovery extent is ∼73% for U(VI) and ~85% for Th(IV)), whereas ligand V containing the maximum number of such phosphorylcarbonyl groups in conformationally non-rigid nitrogen heterocyclic matrix and CEPO (II) containing additional C=O group in the alkyl fragment at the nitrogen atom of carbamoyl fragment exhibit considerable preference in the extraction of lanthanides (extraction of gadolinium with this compound is close to 92%). Obtained data display that highly efficient and selective extractants for both 4f and 5f elements can be constructed on the basis of (2-carbamoylethyl)diphenylphosphine oxides.