Extraction ability of 4-benzoyl-3-phenyl-5-isoxazolone towards 4f-ions into ionic and molecular media

Abstract

The distribution constants of 4-benzoyl-3-phenyl-5-isoxazolone (HPBI) and deprotonated one (PBI-) between hydrophobic ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C 1 C 4 im][Tf 2 N]) and aqueous phases were determined, together with the acid-dissociation constant of HPBI. The solvent extraction of three selected lanthanoid ions (La 3+ , Eu 3+ , and Lu 3+ ) with HPBI from aqueous nitrate phase into [C 1 C 4 im][Tf 2 N] has been investigated. Application of the ionic liquid as the extracting phase greatly enhanced the extraction performance of HPBI for lanthanoid ions compared with that in the chloroform system. A slope analysis was conducted in order to compare the results of the solution 4f-ion coordination chemistry in ionic and molecular media. The composition of the extracted species was established to be anionic tetrakis entities, Ln(PBI) 4- , for light, middle, and heavy lanthanoid ions in an ionic environment (Ln denotes lanthanoid ion). Nevertheless, the typical neutral chelate lanthanoid complexes of the type Ln(PBI) 3 have been detected when the conventional molecular diluent chloroform was applied as an organic phase.