Question

What happens when chlorine is passed in boiling toluene in the presence of sunlight?

Answer 1

When benzene diazonium chloride is treated with an aqueous solution of potassium iodide:

1. The diazonium group \[\ce{(-N^+_2Cl^-)}\] is replaced by the iodide ion (I⁻) from potassium iodide.
2. This reaction is a type of Sandmeyer reaction involving nucleophilic substitution.
3. Benzene iodide (iodobenzene) is formed, and nitrogen gas (N₂) is released.
4. The overall reaction can be represented as:
   \[\mathrm{C_6H_5N_2^+Cl^- + KI \rightarrow C_6H_5I + KCl + N_2 \uparrow}\]
5. The released nitrogen gas escapes as bubbles, confirming the reaction.
6. This method is used to prepare aryl iodides from diazonium salts.