4-acylbis(1-phenyl-3-methyl-5-pyrazolones) as extractants for f-elements

The liquid-liquid extraction of early actinides such as thorium(IV) and ura nium(VI) and trivalent lanthanoids such as neodymium(III), europium(III) an d lutetium(III) from nitrate solutions was studied using 4-sebacoylbis(1-ph enyl-3-methyl-5-pyrazolone) (H2SP) and 4-dodecandioyl-bis(1-phenyl-3-methyl -5-pyrazolone) (H(2)DdP) in chloroform as extractants. The results demonstr ate that these metal ions are extracted into chloroform as Th(SP)(2), Th(Dd P)(2), UO2(HSP)(2), UO2(HDdP)(2), Ln(SP)(HSP) and tn(DdP)(HDdP) with H2SP o r H2DdP. The equilibrium constants of the above species were deduced by non -linear regression analysis. The results clearly highlight that thorium(IV) can be selectively separated from uranium(VI) and trivalent lanthanoids wh en extracted from 0.2 mol/dm(3) nitric acid solutions using 4-acylbis(1-phe nyl-3-methyl-5-pyrazolones). Thorium(IV), uranium(VI) and lutetium(III) com plexes of H2SP were synthesised and characterised by IR and H-1 NMR spectra l data to further clarify the nature of the complexes.