When aniline is treated with a mixture of concentrated and (direct nitration), a surprisingly large — Aromatic Hydrocarbons Chemistry Question

💡 Solution & Explanation

The free amino group is a strong ortho/para director. However, in the highly acidic nitrating mixture, the basic amino group accepts a proton to form the anilinium ion ($Ph-NH_3^+$). The anilinium ion has a full positive charge on nitrogen and no free lone pairs for resonance, exerting a powerful $-I$ effect. This makes it strongly deactivating and meta-directing, leading to the large yield of the meta isomer.