CROWN-ETHERS AS SYNERGISTS IN THE EXTRACTION OF TRIVALENT LANTHANIDESBY 1-PHENYL-3-METHYL-4-TRIFLUOROACETYL-PYRAZOLONE-5

Synergistic extraction of trivalent lanthanides such as Nd, Eu and Tm with mixtures of 1-phenyl-3-methyl-4-trifluoroacetylpyrazolone-5 (HPMT FP) 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 fou nd to be extracted as Ln(PMTFP)(3) with HPMTFP alone and in the presen ce of crown ether (CE) as Ln(PMTFP)(3) . CE. The equilibrium constants of the above species are found to increase monotonically with decreas ing ionic radii of these metal ions. The addition of a crown ether to the metal chelate system not only enhances the extraction efficiency b ut also improves the selectivities among these trivalent lanthanides.