Oxidation of secondary alcohols to ketones
From Wikipedia, the free encyclopedia
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. The hydrogen from the hydroxyl group is lost along with the hydrogen bonded to the second carbon. The remaining oxygen then double bonds with the carbon. This leaves a ketone, as R1-CO-R2. Ketones cannot normally be oxidised any further because this would involve breaking a C-C bond, which requires too much energy [1].
The reaction can occur using a variety of oxidants.
Contents |
[edit] Potassium dichromate(VI)
 |
Please help improve this section by expanding it. Further information might be found on the talk page or at requests for expansion. |
A secondary alcohol can be oxidised into a ketone using acidified potassium dichromate(VI) and heating under reflux.
The orange dichromate(VI) ion, Cr2O72-, is reduced to the green Cr3+(aq) ion.
[edit] Dess-Martin oxidation
|
|
Please help improve this section by expanding it. Further information might be found on the talk page or at requests for expansion. |
The Dess-Martin Reagent is a mild oxidant for the conversion of alcohols to aldehydes or ketones.[2]
The reaction is peformed under stadard conditions, at room temperature, with either dichloromethane or trichloromethane. The reaction takes between half an hour and two hours to complete. The products are then separated from the byproduct, an idodo compound. [3]
[edit] Swern oxidation
Swern oxidation oxidises secondary alcohols into ketones using oxalyl chloride and dimethyl sulphoxide. It also produces an organic base, such as triethylamine.
The by-products are dimethyl sulphide (Me2S), carbon monoxide (CO), carbon dioxide (CO2) and - when triethylamine is used as base — triethylammonium chloride (C6H15NHCl). Dimethyl sulphide and carbon monoxide are very toxic and volatile compounds, so the reaction and the work-up needs to be performed in a fume cupboard.
[edit] Oppenauer oxidation
[edit] See also
[edit] References
- ^ Burton, George et al (2000). Salters Advanced Chemistry: Chemical Ideas (2nd ed.). Heinemann. ISBN 0-435-63120-9
- ^ Dess, D. B.; Martin, J. C. J. Am. Chem. Soc. 1991, 113, 7277-7287.
- ^ 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, 2131-2135
 |
This chemical reaction article is a stub. You can help Wikipedia by expanding it. |
