Nitrobenzene contains the nitro group, i.e. #-stackrel(+)N=O(-O^(-))#, i.e. the nitrogen centre is formally quaternized, and bears a formal positive charge. And thus the aryl ring is deactivated towards aromatic, electrophilic substitution. In fact, the lack of reactivity means that we can use nitrobenzene as a high boiling-point solvent in #"Friedel Crafts reactions"#.
When we try to make #"1,3-dinitrobenzene"#, or #"1,3,5-trinitrobenzene"# we must USE EXCESSIVELY potent electrophiles, i.e. concentrated nitric and hydrochloric acids to effect the reaction.
