Solvent Extraction of Silver(I) as Anionic Metal Complexes with 2-Thenoyltrifluoroacetone and 4-Isopropyltropolone into Chloroform in the Presence of Tetrabutylammonium Ions

The solvent extraction of silver(I) in aqueous 0.1mol dm-3 sodium nitrate solutions with 2-thenoyltrifluoroacetone (Htta) and 4-isopropyltropolone (β-isopropyltropolone, Hipt) into chloroform was studied in the absence and presence of tetrabutylammonium ions (tba+), and the results were compared. Although extraction with Htta was poor, it was very much enhanced and nearly quantitative extraction was achieved by the addition of tba+. This was assumed to be due to the fact that the complex, Ag(tta), was hydrophilic due to its hydration, but tba+Ag(tta)2-, which was extracted in the presence of tba+, was very weakly hydrated and bulkier. Both Ag(ipt) and Ag(ipt)(Hipt) were extracted; extraction with Hipt was not very effective in the absence of tba+. By the addition of tba+, the anionic complex, tba+Ag(ipt)2-, was also extracted, and nearly quantitative extraction was also achieved. Since the formation of this anionic complex is made by an exchange of ipt- with Hipt of the Ag(ipt)(Hipt) species, the enhancement of extraction was impaired by the dissociation of Hipt from the self-adduct.