Other neutral donor extractants

Moyer, B.A., Caley, C.E. 1988. Hydration and aggregation of monofunctional sulfoxide and other neutral oxygen-donor extractants The di(2-ethylhexyl)sulfoxide, dodecane, water system. Solvent Extr. Ion Exch. 6 (5) 785-817. 

The organic phase formation constants of adducts between metal chelate and the neutral donor, in the extraction with combinations of acid chelates and neutral extractants, have also been used as a measure of synergism19. When extended to other combinations of extractants such equilibria may not give a complete picture of synergism in view of many other competing equilibria. 

The equilibria usually encountered in the extraction of metal ions with combinations of betadiketones and neutral donors have been more widely investigated as compared with other systems and hence a detailed account of the same is given below. 

The equilibria involved in the extraction of the actinide ions by neutral donor combinations with chelating extractants such as betadiketones is better understood compared to those when other combinations are used. This is primarily due to the limited number... 

Although this makes the quantitative extraction of the rare earths possible in a single extraction it does not necessarily improve the selectivity of the extraction method because many other elements are also quantitatively extracted. Sieck (197 L) reported that the rare earths were quantitatively extracted in a single stage operation by various fluorinated -diketones and dibutylsulfoxide (the neutral donor). These ternary complexes were sufficiently volatile that several individual rare earths could be separated by gas-liquid chromatography. 

Beta-diketones have been used as efficient extractants for actinides from weakly acidic medium (Manchanda et al., 2009). In view of being acidic extractants, an increase in the feed acidity decreases the metal ion extraction. On the other hand, the presence of neutral donor ligands leads to S5mergism and hence to higher metal ion extraction compared to the beta-diketone alone at a given acidity. 

There are other versions of a similar principle. For the extraction of anionic surfactants [59], which are permanently charged, trihexyl amine was used as a carrier. The carrier is added to the sample in the donor. In the acidic donor this amine is charged, and can form ion-pair with the analytes, while in the alkaline acceptor, the amine is neutralized, thus killing the ion-pair. 

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