Question

Why only chlorine and bromine gives substitution reaction?

Answer 1

The electrophilic substitution reaction between benzene and chlorine or bromine. Benzene reacts with chlorine or bromine in an electrophilic substitution reaction, but only in the presence of a catalyst. ... These compounds act as the catalyst and behave exactly like aluminum chloride in these reactions.

Answer 2

Because bromine stick and replaces H2, where as other one can't