Question

What is the necessary condition for halogenation in benzene?

Answer 1

Necessary conditions for halogenation in benzene:

• Benzene reacts with halogens such as bromine/chlorine in an electrophilic substitution reaction only in the presence of a catalyst that is Ferric chloride $\left({\mathrm{FeCl}}_3\right)$.
• Iron is not a catalyst so it reacts with bromine or chlorine depending upon the reaction and leads to the formation of Ferric bromide $\left({\mathrm{FeBr}}_3\right)$ or Ferric chloride $\left({\mathrm{FeCl}}_3\right)$ respectively.
• Iron is used as a catalyst in halogenation reactions as it is cheaper and readily available.

Halogenation reaction is depicted below:

• Benzene reacts with halogens such as bromine/chlorine in an electrophilic substitution reaction only in the presence of a catalyst that is Ferric chloride $\left({\mathrm{FeCl}}_3\right)$ it yields chlorobenzene and hydrochloric acid.
• The chemical reaction for chlorination can be depicted as: