Crown Ethers as Synergists in the Extraction of Trivalent Lanthanides by 1 -Phenyl-3-methyl-4-trifluoroacetyl-pyrazolone-5

Abstract

Synergistic extraction of trivalent lanthanides such as Nd, Eu and Tm with mixtures of l-phenyl-3-methyl-4-trifluoroacetylpyrazolone-5 (HPMTFP) and 18-crown-6 or dibenzo-18-crown-6 or 15-crown-5 or monobenzo-15-crown-5 (CE) in chloroform has been investigated. Lanthanides are found to be extracted as Ln(PMTFP) 3 with HPMTFP alone and in the presence of crown ether (CE) as Ln(PMTFP) 3 · CE. The equilibrium constants of the above species are found to increase monotonically with decreasing ionic radii of these metal ions. The addition of a crown ether to the metal chelate system not only enhances the extraction efficiency but also improves the selectivities among these trivalent lanthanides.

Incorporating Size Selectivity into Synergistic Solvent Extraction: A Review of Crown Ether-Containing Systems

“…The stoichiometries of the trivalent lanthanide complexes extracted by B15C5 and HPMBP compare favorably with those observed in the HTTA/crown ether systems; however, an examination of the synergistic constants shows that there is a general discontinuity in the extraction of Gd(III) (i.e., unusually low in CCl 4 and unusually high in CHCl 3 ) compared to Pr(III) and Yb(III), which have larger and smaller ionic radii, respectively. No explanation is presented, although a similar discontinuity is observed for Eu(III) extraction compared to that of Nd(III) and Tm(III) by 15- and 18-membered macrocycles with 3-methyl-1-phenyl-4-(trifluoroacetyl)pyrazol-5-one (HPMTFP, Figure ) in CHCl 3 …”

“…No explanation is presented, although a similar discontinuity is observed for Eu(III) extraction compared to that of Nd(III) and Tm(III) by 15-and 18membered macrocycles with 3-methyl-1-phenyl-4-(trifluoroacetyl)pyrazol-5-one (HPMTFP, Figure 1) in CHCl 3 . 103 Tri-, tetra-, and hexavalent actinide extraction from ClO 4media into toluene solutions of 12C4, 15C5, 18C6, DCH18C6, or DB18C6 and HPMBP did not correlate with the macrocyclic cavity size but rather with the etheric oxygen donor basicity. 104 Each crown ether is reported to synergize extraction of Am(PMBP) 3 , Th(PMBP) 4 , or UO 2 (PMBP) 2 , as previously observed in the HTTA extraction systems.…”

“…108 Most interestingly, however, there is no significant synergistic enhancement of Eu(III) extraction by 18C6 compared to Nd(III) or Tm(III), as discussed previously for the extraction of Eu(III) by acylpyrazolones. 101,103 Based on these data, it is not yet clear how the different steric requirements of the isoxazolones and the acylpyrazolones influence synergistic effects.…”

Synergistic Efficiency of 2-[(1-Aza-15-crown-5)-1-ylmethyl)]-4-(phenyldiazenyl)-naphthalen-1-ol in the Liquid Extraction of Light Lanthanoid(III) Ions with 4-Benzoyl-3-phenyl-5-isoxazolone: The Role of Aza-Crown and Azo-Dye Fragments on the Extraction Ability

“…5,40 But the equilibrium concentration of 15C5 was calculated using the partition coefficient (log K D = 0.9) taken from the literature. 5 a The values of the equilibrium constants are calculated on the basis of the 42 experimental points; the statistical confidence is 95 %, and the standard deviation is less than ± 0.05.…”

Diazopyrazolones as weak solvent extractants for copper from ammonia leach solutions †

“…Acylpyrazolones (Fig. 1) also form neutral β-diketonate-type complexes suitable for extraction of a range of metals into organic solvents 11- 16 and have been considered 17 as alternatives to LIX54  for use in ammoniacal leach circuits. Although they are stronger copper extractants than LIX54  , the low solubility of their metal complexes limits 18 their usefulness.…”