Halogen Substitution or Free Radical Halogenation
Halogen substitution, also known as free radical halogenation, is a type of halogenation reaction in which a halogen atom replaces a hydrogen atom in an organic compound. This reaction is typical of alkanes and alkyl-substituted aromatics and proceeds by a free-radical chain mechanism.
Electrophilic Substitution Reaction or Halogenation of Aromatic Compounds
Halogenation of aromatic compounds is a type of electrophilic substitution reaction in which a hydrogen atom on an aromatic ring is replaced by a halogen atom. This reaction is typical of benzene and its derivatives and requires a Lewis acid catalyst, such as AlCl3, FeCl3, FeBr3, or ZnCl2, to activate the halogen and make it a strong electrophile.
The reaction proceeds through three steps:
- Activation of the electrophile by the catalyst.
- Attack of the activated electrophile on the aromatic ring.
- Deprotonation to regenerate the aromatic ring.
Halogenation of Benzene
Halogenation of benzene is an electrophilic substitution reaction that occurs in the presence of a catalyst, such as aluminum chloride or iron (III) bromide. Benzene reacts with chlorine or bromine, replacing one of the hydrogen atoms on the ring with a chlorine or bromine atom. The reactions happen at room temperature. Iron is usually used as a catalyst because it is cheaper and more readily available.
Halogenation Mechanism Benzene involves the formation of an electrophile, which attacks the benzene ring. The halogenation of methylbenzene can result in substitution into the ring or the methyl group, depending on the conditions.
Halogenation of Benzene:
C6H6 + X2 (MX3) → C6H5X + HX
where,
- X is Halogen (Chlorine or Bromine)
- MX3 is Catalyst (FeBr3 or AlCl3).
This reaction results in substitution of one of hydrogen atoms on benzene ring by a halogen atom, with the formation of hydrogen halide as a byproduct. The specific halogen used will determine the halogenated product.
Halogenation
Halogenation is a chemical process that involves adding halogen atoms into compounds. This reaction is common in organic chemistry and has diverse applications, from making drugs to flame retardants.
In this article, we will discuss about Definition of Halogenation, Types of Halogenation Reactions, Examples, and Others in detail.
Table of Content
- What is Halogenation?
- Types of Halogenation Reactions
- Mechanism of Halogenation
- Halogenation of Different Organic Compounds
- Factors Affecting Halogenation
- Applications of Halogenation