Question

Give plausible explanation for the following: (a) Diazonium salts of aromatic amines are stable.
(b) Aniline does not undergo Friedel–Crafts reaction.
(c) Aniline on nitration gives a substantial amount of meta product.

Hint:

Amine group becomes protonated under acid, changing its directive influence and reactivity.

Answer 1

(a) Stability due to resonance and delocalization of \(\ce{N_2^+}\) over benzene ring. (b) Aniline forms a Lewis acid–base complex with AlCl\(_3\) → deactivates ring. (c) In acidic medium, aniline gets protonated to \(\ce{Ph–NH3^+}\), a meta-directing group. \[ \boxed{\text{Acidic conditions lead to meta product due to protonation}} \]