Synthesis of Macrocyclic Ligands and their Application in the Separation of Rare Earths

Summary

New macrocyclic and macroacyclic Schiff bases have been obtained by condensation of 2,6-diformyl-4Z-phenols (Z = Cl, CH₃, (CH₃)₃C) with the polyamines, 1,5-diamino-3-azapentane, 1,5-diamino-3-thiapentane and octadecylamine or 4-N-dodecyldiethylenetriamine. Their interaction with lanthanide(III) (Ln(III) = La, Ce, Sm, Eu, Tb, Dy, Yb) and the uranyl(VI) ions have been studied. The presence of aliphatic chains in the periphery of the coordination moiety of these ligands considerably enhances the solubility of the related complexes in organic solvents. The complexes, formulated as Ln(H₂L)(X)₃.nH₂O or UO₂L (H₂L — unionized macrocyclic or macroacyclic ligands; X = NO³⁻, CI⁻¹ n = 1, 0) have been synthesized by template procedure or by reaction of the appropriate metal salt with the preformed ligands. A study of the phase transfers of trivalent rare earths from nitrate and/or chloride media through an organic membrane to a receiving aqueous solution by the macrocyclic compounds has been undertaken and the results obtained for the extraction, transport and stripping of dysprosium (III) and lanthanum (III) ions are reported.