The behavior of yttrium- and lanthanum-complexes containing thenoyltrifluoroacetone in organic solvents

Abstract

In order to clarify synergistic effect of organic bases in solvent extraction of rare earth metals, the stability of complexes, HPi+[M(TTA)4]- (HPi+:γ-picolinium cation, TTA : thenoyltrifluoroacetonate anion, M: Y and La) in basic acetone and in basic dichloromethane was studied by PMR spectroscopy. The La-complex dissociated into a tris-complex in acetone as follows: HPi+[M(TTA)4]-→M(TTA)3+ HTTA+Pi…(I) It was the same reaction that had been proposed by the authors for the Y-complex in acetone. In dichlorometane, both complexes were more stable and the reaction (I) could not be observed. With addition of tributylphosphate (TBP) to acetone solution of the La-complex and to dichloromethane solutions of both complexes, the following reaction, also already proposed for the Y-complex in acetone, occured: HPi+[M(TTA)4]-+nTBP →M (TTA)3nTBP+HTTA+Pi…(II) Effect of metals or solvents on the equilibrium constant of the reaction (II) could be estimated. The La-complex has a larger constant than the Y-complex, and as for each complex, a larger constant was obtained in acetone than in dichloromethane. © 1976, The Japan Society for Analytical Chemistry. All rights reserved.