Deoxygenation

Deoxygenation is a chemical reaction involving the removal of oxygen atoms from a molecule. The term also refers to the removal molecular oxygen (O₂) from gases and solvents, a step in air-free technique and gas purifiers. As applied to organic compounds, deoxygenation is a component of fuels production as well a type of reaction employed in organic synthesis, e.g. of pharmaceuticals.

The main examples involving replacement of an oxo group by two hydrogen atoms (A=O → A) is hydrogenolysis. Typical examples use metal catalysts and H2 as the reagent. Conditions are typically more forcing than hydrogenation.

Stoichiometric reactions that effect deoxygenation include the Wolff-Kishner reduction for aryl ketones. The replacement of a hydroxyl group by hydrogen (A-OH → A-H) is the point of the Barton-McCombie deoxygenation and the Markó-Lam deoxygenation.

Oxygen groups can also be removed by reductive coupling of ketones, as illustrated by the McMurry reaction.

Epoxides can be deoxygenated using the oxophilic reagent produced by combining tungsten hexachloride and n-butyllithium generates the alkene. This reaction in effect is a de-epoxidation:

Phosphorus occurs in nature as oxides, so to produce elemental form of the element, deoxygenation is required. The main method involves carbothermic reduction (i.e., carbon is the deoxygenation agent).

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