Patent ID: 8841482

Claim:
A method for synthesizing a rare earth metal extractant comprising a dialkyl diglycol amic acid having the general formula (1): wherein R 1 and R 2 are each independently an alkyl group, at least one of R 1 and R 2 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, and removing the aprotic polar solvent.