Question

Given below are two statements:
Statement I: Benzendiazonium salt is prepared by the reaction of aniline with nitrous acid at 273-278 K. It decomposes easily in the dry state.
Statement II: Insertion of iodine into the benzene ring is difficult and hence iodobenzene is prepared through the reaction of benzendiazonium salt with KI.
In the light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement I and Statement II are incorrect.
• B. Statement I is correct but Statement II is incorrect.
• C. Statement I is incorrect but Statement II is correct.
• D. Both Statement I and Statement II are correct.

Hint:

The Sandmeyer reaction is a key method for introducing halogen atoms (like iodine) into the aromatic ring. It involves using a diazonium salt and the corresponding halide ion (KI for iodine).

Answer 1

The Correct Option is C

- Statement I: The preparation of benzene diazonium salt requires the reaction of aniline with nitrous acid (generated in situ from sodium nitrite and hydrochloric acid) at 0-5°C. The temperature range 273-278 K signifies significantly higher temperatures, above room temperature. Therefore, Statement I is incorrect.
- Statement II: Direct iodination of the benzene ring is challenging due to iodine's low reactivity under standard conditions. However, iodobenzene can be efficiently synthesized by reacting benzene diazonium salt with potassium iodide (KI), a process known as the Sandmeyer reaction. Consequently, Statement II is correct.

Thus, the correct option is (3) Statement I is incorrect but Statement II is correct.