An easily accessed class of recyclable hypervalent iodide reagents for functional group oxidations: bis(trifluoroacetate) adducts of fluorous alkyl iodides, CF₃(CF₂)ₙ₋₁I(OCOCF₃)₂
2005
Tesevic, Verona | Gladysz, J. A.
Reactions of commercial fluorous alkyl iodides RfₙI (1-Rfₙ; Rfₙ = CF₃(CF₂)ₙ₋₁; n = 7, 8, 10, 12) with 80% H₂O₂ and trifluoroacetic anhydride give RfₙI(OCOCF₃)₂ (2-Rfₙ; 89–97%). These rapidly oxidize 1,4-hydroquinones in methanol. Subsequent additions of CF₃C₆F₁₁ or FC-72 give liquid/liquid biphase systems. The product quinones are generally isolated in ≥95% yields from the methanol phases, and 1-Rfₙ in ≥95% yields from the fluorous phases. Alternatively, the very low solubilities of 1-Rf₁₀ in 10 ∶ 1 v/v methanol ∶ water or 1-Rf₁₂ in methanol allow efficient recovery via solid/liquid phase separations without recourse to fluorous solvents. The recovered 1-Rfₙ may be reoxidized to 2-Rfₙ and reused.
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