Comparing extraction, synergism and separation of lanthanoids using acidic and neutral compounds in chloroform and one ionic liquid: is the latter always “better”?

Abstract

Five lanthanoid ions were extracted with 3-methyl-1-phenyl-4-(4-trifluoromethylbenzoyl)-pyrazol-5-one alone and in combination with partially substituted calix[4]arenes as synergistic agents using CHCl3 and one IL.

Coordination Chemistry of Europium(III) Ion Towards Acylpyrazolone Ligands

“…In our recent work, it was shown that La(III) was extracted with 3-methyl-1-phenyl-4-(4-trifluoromethylbenzoyl)-pyrazol-5-one in 1-butyl-3-methylimidazolium-bis(trifluoromethanesulfonyl)-imide, ([C1C4im][Tf2N]), as neutral LaL3 chelate but at the same time, the composition of the extracted species was established as LaL3·HL in CHCl3. 14 In ILs, it has been shown that lanthanoids maintain the usual coordination number they display in molecular diluents. 25 It is well known that hydrophobic ILs have higher water dissolving ability than conventional organic hydrophobic diluents.…”

“…ii) Formation of self-adduct species LnL3·HL including one unprotonated acidic ligand. 11,14,31 Albinsson has established that in the organic phase (C6H6) at least two complexes exist, LnAa3 and the self-aduct LnAa3·HAa as well as for the lower lanthanoids (especially La) a second self-adduct, LnAa3(HAa)2 was supposed to be extracted with acetylacetone (HAa). 32 The solvent extraction behavior of all 4f-elements has been investigated in aqueous-benzene medium using 3-methyl-1-phenyl-4-benzoyl-5-pyrazolone (HP) and the composition of the species has been determined as LnP3·HP.…”

“…Furthermore, depending on the IL nature, the Tf2N -transfer may be below the detection limits of the NMR technique. 29 Another way that is different from the classical slope analysis 11,14,22,23 to determine the stoichiometry of the extracted species and can give insight into the first coordination sphere, is EXAFS. Distinction between oxygen atoms arising from H2O or Tf2N -or the ligand could be made provided model compounds with known X-ray structure and EXAFS spectra.…”

“…In a fundamental view, this prompted us to synthesize two new europium(III) complexes with different or similar architecture as those formed in solution 11,14 during the liquid-liquid extraction process by applying two acylpyrazolones possessing methyl (+I) or Ph (±M) substituent at the 4-position of the aroyl group. Their structure may be a hint for the determination of the extraction mechanism in ionic liquids (ILs).…”

Alkylation and pre-organisation of diglycolamide ligands on flexible platforms for nuclear waste treatment

“…229 In general the substituent on the benzoyl ring in pyrazolone derivatives had low influence on the extraction efficiency (only 4-trifluoromethyl had a noticeable impact on the D values, Chart 2.43). 230 This topic has also been discussed in a recent review. …”