Moreover, in the
strongly acidic medium, aniline is protonated to form the
anilinium ion which is meta directing That is why besides the
ortho and para derivatives, significant amount of meta derivative
is also formed However, by protecting the –NH2 group by acetylation reaction
with acetic anhydride, the nitration  reaction can be controlled
and the p-nitro derivative can be obtained as the major product (c) Sulphonation:  Aniline reacts with concentrated sulphuric acid
to form anilinium hydrogensulphate which on heating with
sulphuric acid at 453-473K produces p-aminobenzene sulphonic
acid, commonly known as sulphanilic acid, as the major product