"Fluorination" redirects here. For the addition of fluoride to drinking water, see water fluoridation.

Halogenation is a chemical reaction that incorporates a halogen atom into a molecule. More specific descriptions exist that specify the type of halogen: fluorination, chlorination, bromination, and iodination.

In a Markovnikov addition reaction, a halogen like bromine is reacted with an alkene which causes the π-bond to break forming an haloalkane. This makes the hydrocarbon more reactive and bromine as it turns out, is a good leaving group in further chemical reactions such as nucleophilic aliphatic substitution reactions and elimination reactions.

Several main types of halogenation exist, including:

• Free radical halogenation
• Ketone halogenation
• Electrophilic halogenation
• Halogen addition reaction

Likewise in dehalogenation a halogen atom is removed from a molecule as a result of a reaction.

[edit] Examples

The formation of Gold(III) chloride by the chlorination of gold.

Specific halogenation methods are the Hunsdiecker reaction (from carboxylic acids) and the Sandmeyer reaction (arylhalides).

An example of halogenation can be found in the organic synthesis of the anesthetic halothane from trichloroethylene which involves a high temperature bromination in the second step ^[1]:

[edit] See also

• Haloalkane (Alkyl halide)
• Halogenoarene (Aryl halide)
• Free radical halogenation
• Haloketone
• Electrophilic substitution

[edit] References

1. ^ Synthesis of essential drugs, Ruben Vardanyan, Victor Hruby; Elsevier 2005 ISBN 0-444-52166-6