Quinolinium Fluorochromate (QFC), C9H7NH: An Improved Cr(VI)-Oxidant for Organic Substrates

Article abstract of DOI:10.1246/bcsj.67.1894

Yellow-orange crystalline quinolinium fluorochromate (QFC) is easily prepared in a nearly quantitative yield by the interaction of quinoline with CrO3 and hydrofluoric acid in 1:1.5:1 molar ratio.The reagent is stable.Compared with pyridinium fluorochromate (PFC), the new reagent is more soluble in organic solvents and less acidic.QFC in CH2Cl2 readily oxidizes primary, secondary, and allylic alcohols to the corresponding carbonyls, benzoin to benzil, and anthracene and phenanthrene to anthraquinone and 9,10-phenanthrenequinone, respectively.Oxidations work well also in a variety of sensitive environments, e.g. isopropylidene functionality and trimethylsilyl ethers.Organic sulfides are transformed to sulfoxides at room temperature.The facile oxidation of triphenylphosphine to triphenylphosphine oxide by QFC in CH2Cl2 or CH3CN provides a clear evidence for an oxygen-transfer reaction.The reduced product of QFC, isolated after such reactions, has been ascertained to be C9H7NH, a chromium(IV) species.The advantages of QFC have been highlighted.