A Regularity of the Liquid-Liquid Partition Coefficients of Tris(acetylacetonato) Rare Earth(III) Chelates

Abstract

The extraction of La(III), Nd(III), Sm(III), Tb(III) and Lu(III) with acetylacetone in benzene has been studied. The partition coefficients of these tris- (acetylacetonato) rare earth(III) chelates do not show the same value but increase as the atomic number of rare earth increases. From comparison of the experimental partition coefficient with the theoretical partition coefficient for the tris-acetylacetonato metal(III) chelate estimated from the regular solution concept and the cavity formation energy, this tendency is ascribed to the gradual decrease of the hydration of the neutral chelate in the aqueous phase.