The oxidation of secondary alcohols to ketones is an important oxidation reaction in organic chemistry. When a secondary alcohol is oxidised, it is converted to a

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bo ...

. The hydrogen from the hydroxyl group is lost along with the hydrogen bonded to the carbon attached to oxygen. The remaining oxygen then forms double bonds with the carbon. This leaves a ketone, as R₁–COR₂. Ketones are quite resistant to further oxidation as it would require breaking an adjacent C–C bond, but with strong oxidants this may occur and produces esters or

carboxylic acids In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic ...

. The reaction can occur using a variety of oxidants.

Potassium dichromate

A secondary alcohol can be oxidised into a ketone using acidified potassium dichromate and heating under reflux. The orange-red dichromate ion, Cr₂O₇²⁻, is reduced to the green Cr³⁺ ion. This reaction was once used in an alcohol breath test.

PCC (Pyridinium chlorochromate)

Pyridinium chlorochromate (PCC), when used in an organic solvent, can be used to oxidise a secondary alcohol into a ketone. It has the advantage of doing so selectively without the tendency to over-oxidise.

Dess–Martin oxidation

The

Dess–Martin periodinane Dess–Martin periodinane (DMP) is a chemical reagent used in the Dess–Martin oxidation, oxidizing primary alcohols to aldehydes and secondary alcohols to ketones. This periodinane has several advantages over chromium- and DMSO-based oxidants ...

is a mild oxidant for the conversion of alcohols to aldehydes or ketones. The reaction is performed under standard conditions, at room temperature, most often in

dichloromethane Dichloromethane (DCM or methylene chloride, methylene bichloride) is an organochlorine compound with the formula . This colorless, volatile liquid with a chloroform-like, sweet odour is widely used as a solvent. Although it is not miscible with ...

. The reaction takes between half an hour and two hours to complete. The product is then separated from the spent periodinane. J. S. Yadav, et al. "Recyclable 2nd generation ionic liquids as green solvents for the oxidation of alcohols with hypervalent iodine reagents", ''Tetrahedron'', 2004, ''60'', 2131–35

Swern oxidation

Swern oxidation oxidises secondary alcohols into ketones using oxalyl chloride and dimethylsulfoxide. It also requires an organic base, such as triethylamine. The by-products are

dimethyl sulfide Dimethyl sulfide (DMS) or methylthiomethane is an organosulfur compound with the formula (CH3)2S. Dimethyl sulfide is a flammable liquid that boils at and has a characteristic disagreeable odor. It is a component of the smell produced from cook ...

(Me₂S), carbon monoxide (CO), carbon dioxide (CO₂) and – when triethylamine is used as base – triethylammonium chloride (C₆H₁₅NHCl). Dimethyl sulfide and carbon monoxide are very toxic and malodorous compounds, so the reaction and the work-up needs to be performed in a fume hood or outdoors.

Oppenauer oxidation

Fétizon oxidation

Silver carbonate on celite oxidizes alcohols through single electron oxidation by the silver cations.

References

{{Reflist Organic oxidation reactions