Answer: Primary aromatic amine reacts with NaNO 2 /HCl at 0-5°C.
- A Primary aromatic amine reacts with NaNO<sub>2</sub>/HCl at 0-5°C
- B A reduction of the nitro group to the corresponding amine
- C An oxidation of the amine nitrogen to a nitroso group
- D A free radical chain substitution on the aromatic ring
Correct answer: A. Primary aromatic amine reacts with NaNO<sub>2</sub>/HCl at 0-5°C
Explanation: Diazotisation must be performed at 0-5°C; higher temperatures cause decomposition of the diazonium salt.
In aniline, the nitrogen's lone pair is pulled into the benzene ring through resonance, leaving less electron density available to accept a proton - which is why aniline is a much weaker base than methylamine, where the lone pair is fully available.
Concept context
Nitrogen-containing organic compounds. Covers classification (primary, secondary, tertiary), basicity comparison, preparation methods, and reactions including diazotization and coupling, key for understanding dyes and pharmaceuticals.