Contribution of air oxygen to photooxidation of alkanes by vanadium(V) and chromium(VI) oxocomplexes

In photochemical oxygenation of cyclohexane by KVO₃–CF₃COOH or K₂Cr₂O₇–Bu₄NBr–H₂O–CH₂Cl₂ in air the source of oxygen atoms in the product cyclohexanol and cyclohexanone is air dioxygen rather than a metal oxo-complex. In the absence of dioxygen the products of alkane oxygenation are not formed in either of the above systems. At pH=3, Cr(VI) does oxidize cyclohexane to cyclohexanol even in argon atmosphere.

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KVO₃–CF₃COOH K₂Cr₂O₇–Bu₄NBr–H₂O–CH₂Cl₂ , . . , pH=3, Cr(VI) .