Which of the following can be prepared from Sandmeyer's reaction? (A)…

The correct answer is Option (4) → (A) and (B) only

Sandmeyer reaction is used to replace the diazonium group (–N₂⁺) in an aromatic diazonium salt with chlorine, bromine, or cyanide using copper(I) salts.

General reaction:

Ar–N₂⁺X⁻ → (CuCl / CuBr) → Ar–Cl or Ar–Br + N₂

Thus, Sandmeyer reaction is commonly used to prepare:

• Chlorobenzene (using CuCl)
• Bromobenzene (using CuBr)

Chlorobenzene

Prepared by reacting benzene diazonium chloride with CuCl.

C₆H₅N₂⁺Cl⁻ → CuCl → C₆H₅Cl + N₂

Bromobenzene

Prepared by reacting benzene diazonium salt with CuBr.

C₆H₅N₂⁺Cl⁻ → CuBr → C₆H₅Br + N₂

Iodobenzene

Iodobenzene is formed by treating benzene diazonium salt with KI. This reaction does not require copper salts, so it is not a Sandmeyer reaction.

Fluorobenzene

Fluorobenzene is prepared by the Balz–Schiemann reaction, not by the Sandmeyer reaction.