Answer: Diazonium salt coupling with activated aromatic compound.
- A Diazonium salt coupling with activated aromatic compound
- B Catalytic reduction of a nitro compound to the corresponding amine
- C Oxidation of an aliphatic amine to a nitroso compound
- D Acid hydrolysis of an amide to the carboxylic acid
Correct answer: A. Diazonium salt coupling with activated aromatic compound
Explanation: Azo dyes are made by coupling an electrophilic diazonium ion with a nucleophilic (electron-rich) aromatic ring.
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.