Oxidation of Cerium(III) during Solvent Extraction with Benzoyltrifluoroacetone into Carbon Tetrachloride in the Absence and Presence of Tetrabutylammonium Ions

抄録

Cerium(III) in aqueous 0.1mol dm^-3 sodium nitrate solutions was extracted with benzoyltrifluoroacetone (Hbfa) into carbon tetrachloride in the absence and presence of tetrabutylammonium (tba⁺). In the absence of tba+, only the Ce(bfa)₃ was extracted; in its presence, however, not only was the ternary complex (Ce(bfa)₄-tba⁺) also extracted, and the extraction was much better. When the two-phase agitation was continued, the organic phase gradually changed from colorless to brown in the absence of tba⁺ due to the oxidation of the metal ions in the complex in the organic phase to the cerium(IV). However, in the presence of tba⁺, the organic phase remained colorless for a long time and, thus, oxidation of the cerium(III) was negligible. The rate of oxidation of cerium(III) in the Ce(bfa)₃ complex in carbon tetrachloride to the cerium(IV) by forming the Ce(bfa)₄ complex was measured by spectrophotometry. The rate of this oxidation was found not to be affected by the ligand concentration.