Hydration
Ethene gives ethanol through hydration.
- Reagents
- Steam; phosphoric acid catalyst
- Conditions
- Industrial vapour-phase catalytic hydration
- Reaction class
- Hydration
- Equation
- C2H4 + H2O <=> C2H6O
Overview
Ethene gives ethanol through hydration.
Transformation
- Equation
- C2H4 + H2O <=> C2H6O
- Reactants
- Ethene + Water
- Products
- Ethanol
- Reagents
- Steam; phosphoric acid catalyst
- Environment
- Industrial vapour-phase catalytic hydration
- Reaction class
- Hydration
- Mechanism
- hydration
- Evidence level
- source-backed molecular example
Reference procedure
Industrial hydration of ethene
Ethene + steam → ethanol (reversible)
Materials and quantities
- Ethene and steam
- Phosphoric(V) acid supported on silica catalyst
Apparatus
- Pressurised catalytic reactor
- Cooling and condensation equipment
- Fractional distillation equipment and gas recycle
Procedure
- Pass ethene and steam over the supported phosphoric acid catalyst at about 300 °C and 60–70 atm.
- Cool the reactor outlet to condense ethanol and water.
- Separate unreacted ethene and return it to the reactor feed.
Work-up and isolation
- Separate ethanol from the condensed ethanol–water mixture by fractional distillation.
Critical controls
- The reaction is reversible: per-pass conversion and overall conversion with recycling are different quantities.
- These are industrial conditions, not instructions for assembling a laboratory pressure experiment.
Scope and limitations
- Scope
- Named ethene example; not a class-wide route prediction.
- Limitations
- Reversible reaction with product separation and recycle.
Related reactions
- Iodoform reaction: Ethanol → Triiodomethane products
Ethanol is oxidised and cleaved by alkaline iodine to give triiodomethane and methanoate.
- Partial oxidation: Ethanol → Ethanal
Ethanol is oxidised to ethanal.
- Oxidation: Ethanol → Ethanoic acid
Ethanol is oxidised to ethanoic acid.
- Reduction: Ethanal → Ethanol
Ethanal is reduced to ethanol.
- Esterification: Ethanol → Ethyl acetate
Ethanoic acid and ethanol combine reversibly to form ethyl acetate and water.
- Acid hydrolysis: Ethyl acetate → Ethanol
Ethyl acetate and water react reversibly to form ethanoic acid and ethanol.
- Dehydration: Ethanol → Ethene
Ethanol gives ethene through dehydration.
- Intermolecular dehydration: Ethanol → Diethyl ether
Protonation turns one ethanol OH group into a better leaving group. The oxygen of another ethanol molecule displaces water, and deprotonation gives diethyl ether; stronger dehydration conditions instead favour ethene.
- Hydrolysis: Bromoethane → Ethanol
Hydroxide attacks the saturated carbon bearing bromine while the C-Br bond breaks. This primary-substrate SN2 route replaces bromide with OH and preserves both carbon atoms; aqueous conditions favour this branch over elimination.
- Elimination: Bromoethane → Ethene
The base removes a hydrogen from the carbon next to bromine. The C-H electrons form the C=C pi bond as bromide departs, so elimination removes H and Br without changing the two-carbon skeleton.
- Acid hydrolysis: Ethyl butyrate → Ethanol
Water attack and proton transfers permit the ethoxy fragment to leave as ethanol. Re-forming the carbonyl produces butanoic acid on the other branch.
References
- Direct hydration of alkenesJim Clark · Chemguide · 2015
Named molecular transformation examples, checked 2026-09-08.
- Ethene hydration: industrial conditions and separationJim Clark · Chemguide
Catalyst and temperature/pressure checked 2026-09-29; separation and recycle from https://www.chemguide.co.uk/organicprops/alkenes/hydration.html.