Question

Under what reaction conditions does the electrophilic bromination of aromatic compounds usually occur?

Answer 1

Bromination of an aromatic compound by electrophilic substitution requires a Lewis acid catalyst to polarise a bromine to bromine bond,

Explanation:

A bromine molecule needs a Lewis acid catalyst such as Iron (III) bromide to polarise the halogen bond so one bromine atom is electron deficient and the bromine near the Lewis acid is electron rich. A pair of electrons from the six delocalised pi electron system forms a bond by donating them to the electron deficient bromine atom which breaks down the benzene rings aromacity which therefore leads to the ejection of the proton to reform the aromacity of the benzene ring and the proton bonds with the bromide ion to form HBr the product is bromobenzene.