Question

Benzene diazonium chloride on treatment with reagent 'X' gives iodobenzene. The reagent ‘X’ is

• A. Cu\(_2\)I\(_2\)
• B. AgI
• C. I\(_2\)
• D. HI
• E. KI

Hint:

In the Sandmeyer reaction, KI is used to form iodobenzene by replacing the diazonium group with an iodine atom.

Answer 1

Answer: (E)

In the Sandmeyer reaction, benzene diazonium chloride reacts with reagents like copper(I) halides to form halogenated benzene compounds. The specific halogen that is introduced into the benzene ring depends on the reagent used. - Option (A): Cu\(_2\)I\(_2\) is used in the Sandmeyer reaction to introduce an iodine atom into the benzene ring. This is a correct reagent, but the molecular structure of the halide is more specific to KI. - Option (B): AgI is not typically used to introduce iodine into the benzene ring in the Sandmeyer reaction.
- Option (C): I\(_2\) is not typically used in the Sandmeyer reaction directly. Iodine alone does not react as efficiently with benzene diazonium chloride.
- Option (D): HI (Hydroiodic acid) can react with diazonium salts to give iodobenzene, but KI is generally used in this reaction to specifically produce iodine as a halogen.
- Option (E): KI (Potassium iodide) is the correct reagent. Potassium iodide (KI) reacts with benzene diazonium chloride to form iodobenzene. This is a well-known Sandmeyer reaction that produces iodobenzene efficiently.
Thus, the correct answer is (E) KI, which reacts with benzene diazonium chloride to produce iodobenzene.