Solvent Extraction of Selenium(IV) with 2-Thenoyltrifluoroacetone

Thenoyltrifluoroacetone: Preferable Molecule for Solvent Extraction of Metals—Ancient Twists to New Approaches

“…As a whole, the larger synergistic effect with phenanthroline is probably due to its stronger donor properties [128]. Moreover, the obtained SC values in the cited study (Table 8) are much higher than those in the cases when diphenylsulfoxide [115], crown ethers [110], or calix [4]arenes [13,60,133] were used as a second extractant for the synergistic extraction of Ln 3+ with a β-diketone. In conclusion, the stability of these mixed-ligand adducts in organic diluents (as a rule, they are insoluble in water) depends on many factors, including the terminal groups of the β-diketone, its acidity and steric hindrance, the basicity of the donor atom(s) in the organic base and its structure, and the size of the metal atom too [134].…”

“…The very-high synergistic enhancement shows that the possible interaction between the extractants in the organic phase can be neglected; otherwise, an antagonistic effect would occur [109,110]. The SC values obtained in this case of acidic/neutral coupling are approximately two times higher than the case when HPBI (4-benzoyl-3-phenyl-5-isoxazolone) was used as a chelating extractant instead of HTTA in combination with the same synergist [60], as well as in comparison with the combination of HTTA and another calixarene, 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis-(dimethylphosphinoylmethoxy)calix [4]arene [13] (see Figure 2).…”

“…In fact, HTTA (pK a = 6.2) is less basic and, hence, yields more stable chelates; (ii) secondly, HTTA chelates are, of course, insoluble in neutral and to some extent in acidic aqueous solutions, but are soluble in neutral aromatic hydrocarbons or similar non-polar organic diluents; (iii) thirdly, HTTA chelates are stable in highly acidic media and are non-volatile at room temperature. Therefore, this attractive chelating compound has been widely used over the years for the solvent extraction of s- [3], p- [4], d-ions [5], lanthanoids [6][7][8], and actinoids [9,10]. In general, the scientific investigations in the field have been carried out using a variety of organic diluents and different ionic media and ionic strengths in the aqueous phase.…”

“…Moreover, the data found in the study show that the linearity of the four segments to form "inclined W" is preserved in order to address the effect of L (the total angular momentum) [108] (Figure 8). For instance, the addition of a calixarene tert-butylcalix [4]arene tetrakis(N,N-dimethylacetamide) (S) to the chelating extractant HTTA improves the extraction efficiency of the all Ln (III) ions in 4f-series and produces large synergistic effects, up to 10 6 . The very-high synergistic enhancement shows that the possible interaction between the extractants in the organic phase can be neglected; otherwise, an antagonistic effect would occur [109,110].…”

“…Note: S1: 5,11,17,23-tert-butyl-25,26,27,28-tetrakis(dimethylphosphinoylmethoxy)calix[4]arene; S7: tertbutylcalix[4]arene tetrakis(N,N-dimethylacetamide); S8: 4-tert-butylcalix[4]arene-tetraacetic acid tetraethyl ester.…”