What is substitution reaction? Explain any two substitution reaction of benzene.

Explanation

Substitution reaction: Reaction in which an atom or group present in a compound is replaced by another atom or group are known as substitution reactions.
Substitution reactions of Benzene:
(a) Benzene reacts with bromine or chlorine in presence of `AlCl_(3)` to given the corresponding halo benzene.
`C_(6)H_(5)+Cl_(2) overset(AlCl_(3))to underset("Chlorobenzene")(C_(6)H_(5)Cl)+HCl`
(b) Benzene on heating with nitration mixture below `60^(@)C` gives nitrobenzne.
`C_(6)H_(5)+HONO_(2) underset(H_(2)SO_(4))overset( lt 60^(@)C)to underset("Nitrobenzene")(C_(6)H_(5)NO_(2))+H_(2)O`