Oxidation of Iron(II) during Solvent Extraction with Benzoyltrifluoroacetone into Carbon Tetrachloride in the Absence and Presence of Tetrabutylammonium Ion or Trioctylphosphine Oxide

Abstract

Abstract The solvent extraction of iron(II) in aqueous 0.1 mol dm−3 sodium nitrate solutions containing ascorbic acid with benzoyltrifluoroacetone (Hbfa) into carbon tetrachloride was studied in the absence and presence of tetrabutylammonium ion (tba+) or trioctylphosphine oxide (TOPO). By the addition of tba+, the tba+Fe(bfa)3− species, and by the addition of TOPO, the Fe(bfa)2TOPOn (n = 1 or 2) species were extracted in addition to the Fe(bfa)2 species and the extraction was greatly enhanced. The iron(II) in the benzoyltrifluoroacetonate complex extracted in the organic phase was oxidized rather quickly and the rate of this oxidation was also studied. An addition of tba+ or TOPO to the system slowed down the oxidation reaction, and the reason for the effects of tba+ and TOPO on the rate of oxidation is discussed.