Oxidation of Other Saturated Hydrocarbons

Oxidation with Stoichiometric Oxidants. Certain peracids reacting with alkanes yield alcohols. Peracetic acid,68 69 perbenzoic acid,70 m-CPBA,71,72 and nitroper-benzoic acids may be used. Alcohols or an equilibrium mixture of the alcohol and the trifluoroacetate77 are formed on the action of pertrifluoroacetic acid. A high degree of regioselectivity (better than 97%), specifically, preferential attack at the tertiary C—H bonds, is usually observed  

Regioselectivities of tertiary vs. secondary attack are in the order 90-500. The oxidation is also stereoselective ensuring a high degree of retention in the transformation of epimeric cycloalkanes73,75 and optically active acyclic alkanes74,75 [Eq. (9.30)]. 

When nonactivated peracids such as peracetic acid or perbenzoic acid are used in oxidation of alkanes, the formation of methane and benzene, respectively, as well as evolution of C02 are observed. This indicates a radical mechanism 68,78 

Since formation of the alcohol is highly stereospecific under such conditions as well, a rapid reaction between the alkyl radical and the reagent in the productdetermining step [Eq. (9.35)] was suggested.78 

Studies with p-ni troperbenzoic acid, a reactive peracid, favor a different mechanism. The high degree of retention observed in oxidation of epimeric cycloalkanes and (—)-2,6-dimethyloctane [Eq. (9.30)], as well as substituent and solvent effects, agree with a cyclic transition state (3) originally suggested by Bartlett79 to interpret epoxidation by peracids  

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