Answer: Replacement of diazonium group by CN, Cl, or Br using CuCN or CuX.
- A Replacement of diazonium group by CN, Cl, or Br using CuCN or CuX
- B Reduction of the diazonium salt to the parent amine using H<sub>3</sub>PO<sub>2</sub>
- C Diazotisation of a primary amine using NaNO<sub>2</sub> and HCl at 0-5°C
- D Coupling of a diazonium salt with phenol to give an azo dye
Correct answer: A. Replacement of diazonium group by CN, Cl, or Br using CuCN or CuX
Explanation: Sandmeyer reaction replaces the diazonium group with CN, Cl, or Br using corresponding cuprous salts.
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.