Question
Account for the following:
Although amino group is o- and p-directing for aromatic electrophilic substitution reaction, aniline on nitration gives a substantial amount of m-nitro aniline.
Solution
The nitration of aniline is carried out using conc. HNO3 and H2SO4. However, in the presence of conc. H2SO4, aniline forms aniline hydrogen sulphate in which the anilinium ion, C6H5NH3+ is meta directing because the positive charge on the nitrogen attracts electrons from the benzene ring.
