Halogenation
Halogenation is a chemical reaction that involves the reaction of a compound with a halogen and results in the halogen being added to the compound. Organic compounds undergo halogenation much more readily than inorganic compounds. Dehalogenation is the reverse of halogenation and results in the removal of a halogen from a molecule. The pathway and stoichiometry of halogenation depends on the structural features and functional groups of the organic substrate, as well as on the specific halogen. Inorganic compounds such as metals also undergo halogenation.
Organic chemistry
Halogenation by reaction type
There are several processes for the halogenation of organic compounds, including free radical halogenation, ketone halogenation, electrophilic halogenation, and halogen addition reaction. The determining factors are the functional groups.
Free radical halogenation
Saturated hydrocarbons typically do not add halogens but undergo free radical halogenation, involving substitution of hydrogen atoms by halogen. The regiochemistry of the halogenation of alkanes is usually determined by the relative weakness of the available C-H bonds. The preference for reaction at tertiary and secondary positions results from greater stability of the corresponding free radicals and the transition state leading to them.
Free radical halogenation is used for the industrial production of chlorinated methanes:
