Question

Nitrobenzene on reaction with conc. HNO₃/H₂SO4 at 80-100°C forms which one of the following products ?

• A. 1, 2-Dinitrobenzene
• B. 1, 3-Dinitrobenzene
• C. 1,4-Dinitrobenzene
• D. 1, 2, 4-Trinitrobenzene

Answer 1

The Correct Option is B

Nitrobenzene undergoes nitration under the action of concentrated nitric acid (HNO₃) and sulfuric acid (H₂SO₄) at high temperatures, typically between 80-100°C. The reaction introduces an additional nitro group (-NO₂) onto the benzene ring.

Mechanism and Reasoning:

1. The nitro group already present on nitrobenzene directs the incoming nitronium ion (generated from the nitric acid and sulfuric acid mixture) to the meta position due to its strong electron-withdrawing nature.
2. Electron-withdrawing groups, such as the nitro group, deactivate the benzene ring and direct electrophilic substitutions to the meta position because they make the ortho and para positions electron-deficient and less reactive.

Conclusion:

Therefore, the nitration of nitrobenzene under these conditions results in the formation of 1,3-dinitrobenzene, where the nitro group attaches to the meta-position relative to the original nitro group.

Correct Answer: 1, 3-Dinitrobenzene

This concludes that among the given options, 1,3-Dinitrobenzene is accurately the product formed under the specified conditions.