Method for synthesizing rare earth metal extractant

摘要

A rare earth metal extractant containing, as the extractant component, dialkyldiglycol amide acid which is excellent in breaking down light rare earth elements is reacted in diglycolic acid (X mol) and an esterification agent (Y mol) at a reaction temperature of 70° C. or more and for a reaction time of one hour or more such that the mol ratio of Y/X is 2.5 or more, and is subjected to vacuum concentration. Subsequently, a reaction intermediate product is obtained by removing unreacted products and reaction residue, and an aprotic polar solvent is added as the reaction solvent. Then, the reaction intermediate product is reacted with dialkyl amine (Z mol) such that the mol ratio of Z/X is 0.9 or more and the aprotic polar solvent is removed. As a consequence, a rare earth metal extractant is efficiently synthesized at a low cost and at a high yield without having to use expensive diglycolic acid anhydride and harmful dichloromethane.

主权项

1. A method for synthesizing a rare earth metal extractant comprising a dialkyl diglycol amic acid having the general formula (1): wherein R1 and R2 are each independently an alkyl group, at least one of R1 and R2 is a straight or branched alkyl group having at least 6 carbon atoms, as the active component, said method comprising the steps of:
reacting X mole of diglycolic acid with Y mole of an esterifying agent, with a molar ratio of Y/X being at least 2.5, at a reaction temperature of at least 70° C. for a reaction time of at least 1 hour, then concentrating in vacuum to remove unreacted reactant and reaction residue, thus obtaining a reaction intermediate product, the reaction intermediate product being obtained by concentrating so that the reaction intermediate product contains diglycolic anhydride having a purity of at least 90%, and further contains minor amounts of unreacted diglycolic acid and unreacted esterifying agent, and without further purification,adding a reaction solvent to the reaction intermediate product, the reaction solvent being an aprotic polar solvent,reacting the reaction intermediate product with Z mole of a dialkylamine, with a molar ratio of Z/X being at least 0.9, andremoving the aprotic polar solvent.