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 involves the reaction of aniline with nitrous acid (generated in situ from sodium nitrite and hydrochloric acid). This reaction occurs at temperatures between 0-5°C, not 273-278 K (which corresponds to much higher temperatures, typically above room temperature). Hence, Statement I is incorrect.
- Statement II: The insertion of iodine into the benzene ring is indeed difficult as iodine does not react readily under normal conditions with the benzene ring. However, iodobenzene can be prepared effectively by reacting benzene diazonium salt with KI (Potassium iodide), which leads to the formation of iodobenzene. This is a typical reaction, known as the Sandmeyer reaction.
Therefore, Statement II is correct.

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