Nitration results in the substitution of a H atom with a -NO2 (nitro) group.

The electrophile is a nitronium ion (O=N+=O) which is generated as follows from the sulfuric acid and nitric acid.

The overall mechanism is the same as we reviewed for halogenation except a nitronium ion behaves as the electrophile.

Reduction of Nitrobenzene

Nitrobenzene and other aromatic nitro compounds can be easily reduced to the corresponding amino (-NH2).  There are numerous methods to achieve this, but Pd/C is often employed on larger scale.

Various metals (Sn, Fe or Zn) in combination with HCl will also reduce nitroarenes to anilines.