dehydrogenate

Dehydrogenate is a chemical term describing the removal of hydrogen from a molecule. In most contexts it refers to reactions that create a new unsaturation, such as a double bond or a carbon–carbon triple bond, with hydrogen gas released as a byproduct. The reverse process is hydrogenation.

Most dehydrogenation reactions involve organic substrates and two main themes: converting alkanes or saturated compounds to more unsaturated products, and converting alcohols to carbonyl compounds. Examples include propane dehydrogenation to propene (C3H8 → C3H6 + H2), cyclohexane becoming benzene (C6H12 → C6H6 + 3H2), and ethanol to acetaldehyde (C2H5OH → CH3CHO + H2). Another industrial example is ethylbenzene dehydrogenation to styrene (C8H10 → C8H8 + H2).

Industrial dehydrogenation is typically endothermic and conducted at high temperatures under low hydrogen partial pressure to shift equilibrium toward products. Catalysts on solid supports, such as platinum- or chromium-based systems, are commonly used to increase rates and selectivity. Non-oxidative dehydrogenation relies on heat and catalysts to remove hydrogen, whereas some processes employ oxidants in oxidative dehydrogenation to aid hydrogen removal.

Applications of dehydrogenation include the production of alkenes and aromatics that serve as building blocks in petrochemicals and fine chemicals. It also plays a role in the processing of fuels and in synthetic chemistry workflows where converting saturated substrates to more reactive unsaturated forms is desirable. The term encompasses both laboratory-scale transformations and large-scale industrial processes, each governed by considerations of thermodynamics, kinetics, and hydrogen management.