Synergic solvent extraction of lanthanides with mixtures of aliphatic fluorinated β-diketones and organophosphorus donors

Abstract

The extraction of lanthanides from an aqueous acetatechloride medium into cyclohexane solutions of trifluoroacetylacetone, hexafluoroacetylacctone, 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione and tri-n-butyl phosphate was studied. The extraction properties of other fluorinated aliphatic β-diketones and fluoroorganophosphates were also investigated. The efficiency of the extraction of the lanthanides, the composition of the complexes transferred to the organic phase and the extraction and stability constants for the synergic reactions were determined. Synergic extraction, as a technique for the preparation of lanthanide species, was evaluated for compatibility with subsequent gas chromatography. The lanthanides were found to be rapidly and quantitatively transferred into organic phases containing mixtures of fluorinated aliphatic β-diketones and TBP. The resulting mixed complexes that contained fully fluorinated β-diketones had a distinct stoichiometry and were thermodynamically more stable dan similar mixed complexes of partially fluorinated β-diketones. These properties of the synergic systems allow precise control of the formation of anhydrous complexes in the organic phase and are compatible with the use of these systems for gas chromatography.