Kinetics and mechanism of the oxidation of alcohols by pyridinium fluorochromate

Abstract

Pyridinium fluorochromate, C₅H₅NHCrO₃F, oxidizes benzyl alcohol, ethanol, and cyclohexanol to benzaldehyde, acetaldehyde, and cyclohexanone, respectively. While each of the oxidation, studied in acetonitrile-nitrobenzene (1 : 1, v/v) medium, is first order with respect to the oxidant, the rate is almost independent of the substrate concentration. The reactions are catalyzed by acid, the acid-catalyzed reactions being very fast, precluded determination of their order in acid medium. The effects of temperatures and solvent compositions were studied and activation parameters evaluated. Probable mechanisms are discussed.