Which one of the following reactions does not occur?

Solution

Chemistry ma’am · 3 steps

Aniline's -NH₂ lone pair grabs AlCl₃ first, so Friedel–Crafts never gets started.

1. Lewis acid meets base. The nitrogen of aniline has a lone pair, so it is a Lewis base. AlCl₃ is a Lewis acid, so the two combine into a salt, C₆H₅NH₂⁺-AlCl₃⁻.
2. Ring gets deactivated. Nitrogen now carries a positive charge and pulls electron density out of the ring. The ring can no longer attack the weak electrophile from CH₃Cl, so no toluidine forms.

   Option	Reagent	What happens	Occurs?
   (a)	(CH₃CO)₂O / pyridine	-NH₂ is acetylated to acetanilide; pyridine removes the acid formed	Yes
   (b)	H₂SO₄, then heat	Anilinium hydrogensulphate forms and rearranges on heating to sulphanilic acid	Yes
   (c)	CH₃Cl / AlCl₃	AlCl₃ binds to N; ring is deactivated	No
   (d)	HNO₃ / H₂SO₄	Nitration gives a mixture of nitroanilines, with para about 51%	Yes

3. So. Aniline does not undergo Friedel–Crafts alkylation, so reaction (c) does not occur.

The idea to keep. Aniline never undergoes Friedel–Crafts alkylation or acylation. The -NH₂ group bonds to AlCl₃ and the positive nitrogen deactivates the ring.

Answer from the NTA final answer key. Solution by PrepWiser.