Shin-etsu Chemical Co., Ltd.

Japan Atomic Energy Agency

Nissin Chemical Industry Co., Ltd.

Kojiro Shimojo

Hirochika Naganawa

Kazuaki Sakaki

Hiroto Sugahara

Tetsuya Kume

Masaki Ohashi

Tetsuya Ohashi

Masahiko Ikka

Takehisa Minowa

In synthesis of a compound represented by the General Formula (1) or a salt thereof, nitrilotriacetic acid as its raw material is reacted with a dehydrating agent to allow dehydration, and the resulting nitrilotriacetic acid anhydride is reacted with a dialkylamine to obtain a reaction intermediate product. The reaction intermediate product is then similarly reacted with a dehydrating agent to allow dehydration, and the resulting reaction intermediate anhydride is reacted with a dialkylamine to synthesize a tetraalkylnitriloacetic acid diacetamide compound. In Formula (1), R, R, Rand Rindependently represent the same or different hydrocarbon group, with the proviso that the total number of carbon atoms in the hydrocarbon groups R, R, R, and Ris 8 to 64.

Method for synthesizing tetraalkylnitriloacetic acid diacetamide compound

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&#xb0; 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. Then a nonpolar or low-polar solvent which is an organic solvent for forming an organic phase during solvent extraction of the rare earth metal and which is capable of dissolving dialkyldiglycol amide acid is added as the reaction solvent, and the reaction intermediate product is reacted with dialkyl amine (Z mol) such that the mol ratio of Z/X is 0.9 or more.

Method for synthesizing rare earth metal extractant

A rare earth metal extractant in the form of a dialkyl diglycol amic acid is synthesized by reacting diglycolic anhydride with a dialkylamine in an aprotic polar solvent, with a molar ratio of dialkylamine to diglycolic anhydride being at least 1.0, and removing the aprotic polar solvent.

Synthesis of rare earth metal extractant

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&#xb0; 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.

A rare earth metal extractant in the form of a dialkyl diglycol amic acid is synthesized by reacting diglycolic anhydride with a dialkylamine in a synthesis medium. A molar ratio (B/A) of dialkylamine (B) to diglycolic anhydride (A) is at least 1.0. A non-polar or low-polar solvent in which the dialkyl diglycol amic acid is dissolvable is used as the synthesis medium.

Solvent extraction from an aqueous phase containing first and second rare earth elements is carried out by contacting an organic phase containing a diglycolamic acid as an extractant and a hydrocarbon or a low-polar alcohol as a solvent, with the aqueous phase below pH 3 for extracting the first rare earth element into the organic phase, back-extracting from the organic phase with an aqueous acid solution for recovering the first rare earth element, and recovering the second rare earth element which has not been extracted into the organic phase and has remained in the aqueous phase.

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Ibaraki, Japan

Kojiro Shimojo