Extraction Properties of Bis(diphenylphosphinylethyl)phosphinic Acid in Nitric Acid Solutions

Abstract

Extraction of microamounts of U(VI), Th(IV), Sc(III), and Ln(III) from HNO 3 solutions with solutions of bis(diphenylphosphinylethyl)phosphinic acid in dichloroethane was studied. The stoichiometry of the extractable complexes was determined, and the effect of the inorganic anion and organic diluent on the extraction of rare-earth elements was examined. An increase in the number of phosphoryl groups in the extractant molecule and replacement of ethylene bridges between the phosphorus atoms by methylene bridges enhance the extraction of metal ions from nitric acid solutions.The interest in extraction properties of polyfunctional organophosphorus acids increased recently, because of the prospects for using these agents in radiochemical practice for the recovery of transplutonium, rare-earth (Ln), and other elements from nitric acid solutions [1]. It was shown that dibasic P, P`-di-(2-ethylhexyl)methylenediphosphonic acid [2, 3] and monobasic (diphenylphosphinylmethyl)phenylphosphinic [4] and bis(diphenylphosphinylmethyl)phosphinic (I) [5] acids exhibit extremely high extractive power toward Th(IV), U(VI), Am(III), and Ln(III) in nitric acid solutions. It was suggested that the high extractive power of acid I is due to the possibility of formation of six-membered chelate rings with metal ions, since the phosphoryl groups in this agent are linked with methylene bridges. In this connection, it is interesting to study how the length of the alkylene bridge between the P(O)OH and P(O) fragments and the number of phosphoryl groups in the extractant molecule affect its extractive power.To this end, we studied the extraction of U(VI), Th(IV), Sc(III), and Ln(III) from aqueous solutions of HNO 3 with solutions of bis(2-diphenylphosphinylethyl)phosphinic (II) and 2-phenylethyl-(2-diphenylphosphinylethyl)phosphinic (III) acids in dichloroethane. For comparison, we also studied the extraction with a neutral analog of II, pentaphenyldiethylenetriphosphine trioxide IV [6], and with diphenylphosphinic acid V.

Direct Regio- and Diastereoselective Diphosphonylation of Cyclic Enamines: One-Pot Synthesis of α,α′-Bis(diphenylphosphoryl)- and α,α′-Bis(diphenylphosphorothioyl)cycloalkanones

“…An important area in the chemistry of organophosphorus compounds is the design of new types of P-ligands containing, along with the phosphoryl or thiophosphoryl moieties, one or more other functional groups (keto, amino, hydroxy, etc.). The interest for these compounds is due to their well-known useful applications, such as in the high-performance extraction of various metals including uranium (VI), thorium (IV), and rare earths (III), [1][2][3][4][5][6][7] in the preparation of ion-selective electrodes, [8][9][10] or as ligands for transitionmetal-catalyzed cross-coupling reactions and asymmetric synthesis. [11][12][13][14][15][16] Some of their fluorescent complexes with lanthanum-group metals are also used as light-emitting components in organic light-emitting diodes.…”