The solvent extraction of europium and barium with 1-aryl-3-methyl-4-aroyl-5-pyrazolones

Abstract Eleven 1-aryl-3-methyl-4-aroyl-5-pyrazolone derivatives were synthesized. Their acid dissociation constants were determined spectrophotometrically; there was a linear relationship between them and Hammett's σ values. Europium and barium ions were readily extracted into benzene and n-octyl alcohol, respectively, at very low pH.