Solvent Extraction of Lanthanides(III) with N‐Cinnamoyl‐N‐phenylhydroxylamine and Its Trifluoromethyl Derivative

Abstract N‐m‐Trifluoromethylcinnamoyl‐N‐phenylhydroxylamine (CF3‐CPHA) was synthesized. The acid‐dissociation constant and distribution constant between chloroform and water of CF3‐CPHA and N‐cinnamoyl‐N‐phenylhydroxylamine (CPHA), which was the mother compound of CF3‐CPHA, were determined spectrophotometrically. The extraction behavior of tervalent lanthanides (Ln), Pr, Eu, and Yb into chloroform solution containing CPHA or CF3‐CPHA was studied. They are extracted as self‐adduct chelates, LnL3(HL)3, where L and HL denote the ligand anion and neutral ligand, respectively. The extraction constants and separation factors for the lanthanides with CPHA and CF3‐CPHA were evaluated. The extraction constant with CPHA are smaller than that obtained with CF3‐CPHA. However, it is observed that CPHA possesses higher selectivity than CF3‐CPHA.