JEE Chemistry 2023 Question with Solution

Step-by-step solution

Standard Method

Given: o-Phenylenediamine is treated with $HNO_3$.

Find: The major product formed.

The provided solution scheme shows that o-phenylenediamine first reacts with nitric acid to form an intermediate, followed by cyclization and loss of water. The final product shown is a benzofused ring containing three nitrogen atoms, which matches option C.

The conclusion in the source solution is that the product is the cyclic nitrogen-containing structure shown in option C.

Therefore, the correct option is C.

Common mistakes

• Assuming simple nitration of the benzene ring. That is incorrect here because the provided solution shows reaction of the amine functionality followed by cyclization. Follow the reaction pathway indicated by the reagent and intermediate formation.

• Choosing a structure with only substitution and no ring closure. That is wrong because the extracted solution image clearly indicates intramolecular cyclization to a fused nitrogen heterocycle. Check whether a new ring is formed.

• Relying only on the textual explanation mentioning nitration and imine language. That wording is inconsistent with the final reaction scheme. Use the final structure shown in the solution image and the declared correct option as the deciding evidence.