BRAINCAKEFriedel-Crafts Alkylation
Friedel-Crafts reactions form a new carbon-carbon bond to a benzene ring. This is important in synthesis because it attaches a carbon chain to an aromatic ring, which most other reactions of benzene cannot do.
In Friedel-Crafts alkylation, benzene reacts with a haloalkane in the presence of a halogen carrier such as AlCl3, forming an alkylbenzene. Conditions must be anhydrous, because water reacts with aluminium chloride and destroys the catalyst.
Mechanism (electrophilic substitution)
1. The halogen carrier generates the electrophile, a carbocation:
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Key terms in this lesson
- carbocation
- A positively charged carbon-containing ion, formed when a carbon atom has only three bonds and a positive charge.
More in Benzene
- Nitration of Benzene
- Halogenation of Benzene
- Phenol
- Halogen Carriers
- Friedel-Crafts Acylation
- Reactivity of Phenol
- Phenol as a Weak Acid
- Bromination of Phenol
All 16 lessons in Benzene · All OCR A-level Organic Chemistry topics