Oxygen of alcohols

Hydrogen abstraction from a position a to the oxygen of alcohols and ethers provides a simple route to a-oxyalkyl radicals. Resonance stabilization and polar factors have been used to explain the ease of radical attack on these substrates. Recent studies appear to exclude the possibility that the oxygen atom in position a to the free C-radical may cause stabilization by resonance. The ease of hydrogen abstraction Avould be determined only by polar factors, arising with electrophilic radicals (X ) in contributions from the polar forms 13-15 to the transition state. 

Oxygenation of alcohols.1 Primary and secondary alcohols are converted into the corresponding aldehydes or ketones by 02, visible light, and H2PtCl6—CuCl2 in the ratio 1 2. Yields are almost quantitative, but rates are reduced by steric factors. 

The mechanism of the aerobic oxidation of alcohols depends on the particular catalyst used. Two general mechanisms can be considered (1) the direct oxygenation of alcohols by 02 through a free-radical chain process initiated by the catalyst, and (2) the direct oxidation of the alcohol by the catalyst, which is then regenerated by 02. Both mechanisms are well illustrated [6] by the aerobic oxidations catalyzed by the persistent tetramethylpiperidine-N-oxyl (TEMPO) radical 1 and the nonpersis-tent phthalimide-N-oxyl (PINO) radical 2. 

Oxidation Adjacent to Oxygen of Alcohols by Chromium Reagents... 

Oxidation A acent to Oxygen of Alcohols by Other Methods OH (ll).Cua2.CaH2.MeCN OH... 

Oxidation Adjacent to Oxygen of Alcohols by Chromium Reagents Table 2 Oxidation of Alcohols with Ci03 py2 (Collins Oxidation)... 

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