Chemistry of Diglycolamides: Promising Extractants for Actinide Partitioning

The historical perspective and recent advances on the fascinating chemistry of diglycolamides, with special emphasis on their proposed applications in radioactive waste management, is presented. Stephan et al. studied the extraction of various metal ions with multidentate amido podands. The open-chain ether dicarboxylic acid diamides (diglycolamides) exhibited very high D values for rare earth ions, viz. La(III) and Yb(III) from picrate and nitrate media at pH 5. Elsewhere, tripodal chelates bearing three DGA units precisely arranged on a triphenoxymethane platform were synthesized to mimic the preferred TTP geometry favored by lanthanides coordinating through oxygen donor atoms. Yaita et al. and Nave et al. reported the presence of N, N,N',N'-tetraoctyl diglycolamide (TODGA) aggregates dispersed in nonpolar diluents. Wilden et al. proposed a 1-cycle SANEX process for the direct selective extraction of trivalent actinides from a simulated PUREX raffinate using a mixture of CyMe4BTBP and TODGA.