Hydration

Overview

Catalytic hydration converts alkenes into alcohols.

Transformation

Alkenes → Alcohols

Equation

RCH=CH2 + H2O -> RCH(OH)-CH3

Reagents

steam

Environment

H3PO4 catalyst, high temperature and pressure

Reaction class

addition

Mechanism

electrophilic addition / hydration

Evidence level

textbook core

Scope and limitations

Scope

Alkenes react with steam under catalytic conditions to form alcohols.

Limitations

Regiochemistry and industrial catalyst details depend on substrate and process conditions.

Related reactions

• Chlorination: Alcohols → Chloroalkanes

  Alcohols can be converted into chloroalkanes to create a better leaving group for downstream substitution.

• Chlorination with thionyl chloride: Alcohols → Chloroalkanes

  Thionyl chloride converts alcohols into chloroalkanes with sulfur dioxide and hydrogen chloride as by-products.

• Bromination: Alcohols → Bromoalkanes

  Bromide and acid conditions convert alcohols into bromoalkanes.

• Iodination: Alcohols → Iodoalkanes

  Iodine and red phosphorus conditions convert alcohols into iodoalkanes.

• Hydrochlorination: Alkenes → Chloroalkanes

  Addition of hydrogen chloride across an alkene can form a chloroalkane.

• Hydrobromination: Alkenes → Bromoalkanes

  Addition of hydrogen bromide across an alkene can form a bromoalkane.

• Hydroiodination: Alkenes → Iodoalkanes

  Addition of hydrogen iodide across an alkene can form an iodoalkane.

• Hydrolysis: Chloroalkanes → Alcohols

  The C-Cl bond can be displaced by hydroxide to form an alcohol.

• Elimination: Chloroalkanes → Alkenes

  Base-promoted elimination removes HCl to form an alkene.

• Hydrolysis: Bromoalkanes → Alcohols

  The C-Br bond can be displaced by hydroxide to form an alcohol.

• Hydrolysis: Iodoalkanes → Alcohols

  The C-I bond can be displaced by hydroxide to form an alcohol.

• Elimination: Bromoalkanes → Alkenes

  Base-promoted elimination removes HBr to form an alkene.

• Elimination: Iodoalkanes → Alkenes

  Base-promoted elimination removes HI to form an alkene.

• Oxidation: Alcohols → Aldehydes

  Controlled oxidation of a primary alcohol gives an aldehyde.

• Oxidation: Alcohols → Ketones

  Oxidation of a secondary alcohol gives a ketone.

• Oxidation: Alcohols → Carboxylic acids

  Full oxidation of a primary alcohol gives a carboxylic acid.

References

1. Organic Chemistry: Hydration of AlkenesJohn McMurry · OpenStax Organic Chemistry · 2023

   Supports acid-catalysed hydration of alkenes to alcohols by alkene protonation, water attack on the carbocation, and deprotonation of the protonated alcohol.