Question

Nitrobenzene on reaction with conc. $ {HNO_3/H_2SO_4 }$ at $ {80-100^{\circ} C}$ forms which one of the following products ?

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

Answer 1

The Correct Option is C

Nitrobenzene is an aromatic compound where a nitro group (-\text{NO}_2) is attached to a benzene ring. When nitrobenzene undergoes nitration using concentrated nitric acid (HNO_3) and sulfuric acid (H_2SO_4) at high temperatures, the nitro group directs additional nitro groups to specific positions on the benzene ring due to its electron-withdrawing nature.

Step 1: Understanding the Reaction

The reaction in question is the nitration of nitrobenzene. In the presence of concentrated HNO_3/H_2SO_4, an additional nitro group is introduced to the benzene ring. Nitro groups are meta-directing due to their strong electron-withdrawing character through resonance and inductive effects, which means that the incoming nitro group preferentially attaches to the meta position relative to the existing nitro group.

Step 2: Reaction Mechanism

When nitrobenzene is treated with concentrated HNO_3/H_2SO_4 at 80-100^{\circ} C, the nitration process leads to the formation of a dinitrobenzene product:

• The nitro group on nitrobenzene directs the incoming nitro group to the meta position.

Step 3: Product Formation

Given the directing effects of the existing nitro group, the bombarded nitro group occupies the meta position to the original nitro group. As such, the product formed is 1,3-dinitrobenzene.

Conclusion: The correct product of the reaction of nitrobenzene with concentrated HNO_3/H_2SO_4 at 80-100^{\circ} C is 1,3-dinitrobenzene.