Dehydrogenation

Dehydrogenation is a chemical reaction that involves the elimination of hydrogen (H₂). It is the reverse process of hydrogenation. Dehydrogenation reactions may be either large scale industrial processes or smaller scale laboratory procedures.

Classes of the reaction

There are a variety of classes of dehydrogenations:

• Aromatization — Six-membered alicyclic rings can be aromatized in the presence of hydrogenation catalysts, the elements sulfur and selenium, or quinones (such as DDQ).
• Oxidation — The conversion of alcohols to ketones or aldehydes can be effected by metal catalysts such as copper chromite. In the Oppenauer oxidation, hydrogen is transferred from one alcohol to another to bring about the oxidation.
• Dehydrogenation of amines — amines can be converted to nitriles using a variety of reagents, such as Iodine pentafluoride (IF₅).
• Dehydrogenation of paraffins and olefins — paraffins like n-pentane and isopentane can be converted to pentene and isoprene using chromium (III) oxide as a catalyst at 500 degree C.

Dehydrogenation converts saturated fats to unsaturated fats. Enzymes that catalyze dehydrogenation are called dehydrogenases. Dehydrogenation processes are used extensively to produce styrene in the fine chemicals, oleochemicals, petrochemicals, and detergents industries.

Feed stocks

Likely feed stocks to be used in this dehydrogenation process include hydrocarbons, such as:

• Ethylbenzene
• Methanol
• Butane
• Butene
• Cyclohexane

Inorganic compounds, such as hydrogen sulfide or hydrogen iodide, are also used.

References

• Advanced Organic Chemistry, Jerry March, 1162-1173.
• http://www.firstprincipals.com/DeHydrogenation.htm