A2-Level Benzene, Aromatic Chemistry

Video Tutorial Electron Orbitals

Quick Notes Acylation of Benzene

Acylation of benzene involves the substitution of an acyl group onto a benzene ring:
Acyl chlorides are reacted with a halogen carrier (AlCl₃) to form an acyl ion, which acts as a strong electrophile and reacts with the benzene ring in an electrophilic substitution reaction.
The reaction requires warm conditions and HCl is formed as a product.

Full Notes Acylation of Benzene

Acylation of benzene refers to the substitution of an acyl group (RCO-) onto a benzene ring.

acylation of benzene reaction acyl chloride halide carrier a-level chemistry

In order to be substituted onto the ring, the acyl group must be an electrophile. Acyl chlorides provide an easy way to form an acyl group with a positive charge on the carbon atom. As with the alkylation of arenes (see Alkylation Reactions), a halogen carrier is used to break the bond between the carbon atom and the chlorine atom in an acyl chloride.

forming acyl ion acylation of benzene acyl chloride and halogen carrier AlCl3 a-level chemistry

The electrophile formed can then react with benzene in a standard electrophilic substitution reaction. See Benzene Reactions.

acylation of benzene mechanism electrophilic substitution

HCl is formed at the end of the reaction. The tetra ion formed from the halogen carrier reacts with the hydrogen ion (H⁺) released during the reaction, forming HCl and the original halogen carrier again.

reforming halogen carrier catalyst acylation of benzene