Hello aspirant, the answer to your question lies in the delocalized electron on benzene ring. Due to the presence of electron cloud of delocalised electron onbenzeneringnucleophilicattack is difficult and thus normally doesnotundergonucleophilic substitutionreaction . Thus preferrably electrophilicsubstitutionoccurs.

Hello!!

There is a basic concept behind this  Due to the presence of electron cloud of delocalised electron on benzene ring nucleophilic attack is difficult ,because elextrons are negarively charged and nucleophiles are also negativelt charged and thus normally does not undergo nucleophilic substitution reaction . Thus preferrably electrophilic substitution occurs.

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