Structure Activity Relationship Approach toward the Improved Separation of Rare-Earth Elements Using Diglycolamides.

The separation of adjacent lanthanides continues to be a challenge worldwide because of the similar physical and chemical properties of these elements and a necessity to advance the use of clean-energy applications. Herein, a systematic structure-performance relationship approach toward understanding the effect of -alkyl group characteristics in diglycolamides (DGAs) on the separation of lanthanides(III) from a hydrochloric acid medium is presented. In addition to the three most extensively studied DGA complexants [,,','-tetra(-octyl)diglycolamide, TODGA; ,,','-tetra(2-ethylhexyl)diglycolamide, TEHDGA; ,'-dimethyl-,'-di(-octyl)diglycolamide, DMDODGA], 12 new extracting agents with varying substitution patterns were designed to study the interplay of steric and electronic effects that control rare-earth element extraction.