Halogenation of benzene is a chemical reaction where a hydrogen atom on the benzene ring is replaced by a halogen atom (like chlorine, bromine, or iodine). This reaction happens through a process called electrophilic aromatic substitution.
In this process:
- A halogen atom is first activated by a catalyst, usually a metal halide like iron(III) chloride or iron(III) bromide, to make it more reactive.
- The activated halogen then attacks the benzene ring, temporarily disturbing its stable electron arrangement.
- A hydrogen atom on the ring is removed, restoring the ring’s aromatic stability, with the halogen now attached to the benzene.
Key points:
- Benzene needs a catalyst for halogenation; it doesn’t react directly with halogens.
- The reaction keeps the benzene ring aromatic, meaning its stable electron cloud is preserved.
- This is commonly used to produce compounds like chlorobenzene or bromobenzene.