Synthesis and Complexing Properties of Three Aminopolyphosphonic Acids with Rare Earth Ions

摘要

Three white crystalline aminopolyphosphonic acids, DTHMP、 TTHMP and TPHMP were synthesized by a modified Mannich reaction under gentle conditions. The products were isolated and purified with a SP Sephadex C 25 column. The acid base and complexing properties of three aminopolyphosphonic acids with rare earth ions were investigated by means of potentiometric titration in aqueous medium at (25±0 1)℃ and ionic strength I =0.1 mol/L KNO 3. The successive protonation constants of ligands and the formation constants of complexes with rare earth elements were obtained. The results show a double double effect for lgK MH iL against atomic number of lanthanide. The properties are advantageous for the separation of the rare earth elements.