2,2'-(Methylimino)bis(N,N-dioctylacetamide) (MIDOA), A New Tridentate Extractant for Technetium(VII), Rhenium(VII), Palladium(II), and Plutonium(IV)

2,2'-(Methylimino)bis(N,N-dioctylacetamide) (MIDOA) was developed as a new extractant for technetium. MIDOA has a similar backbone to TODGA, N,N,N',N'-tetraoctyldiglycolamide, where the nitrogen atom bearing a methyl group replaces the ether oxygen in TODGA. MIDOA is highly lipophilic and ready to use in the HNO3-n-dodecane extraction system. The distribution ratio (D) for Tc(VII) is extremely high. In addition, Cr(VI), Re(VII), Mo(VI), W(VI), Pd(II), and Pu(IV) are well extracted by MIDOA. MIDOA has high selectivity toward certain oxometallates. The D(Tc) values decrease gradually with HNO3, H+, and NO3 - concentrations, and the log D vs log [MIDOA] dependence indicates the species extracted to be the 1:1 metal-ligand complex. It is clear that MIDDA [2,2'-(methylimino)bis(N,N-didodecylacetamide)] and IDDA [2,2'-(imino)bis(N,N-didodecylacetamide)], which have structures analogous to MIDOA, have similar extraction behavior to that of MIDOA.