Question

What is the product obtained on the reaction of chlorobenzene with concentrated HNO3?

• A. Para nitro chloro benzene
• B. Ortho nitro chloro benzene
• C. Mixture of ortho and para nitro benzene
• D.

Hint:

When working with aromatic substitution reactions, remember that the position of substitution is influenced by the nature of the substituent on the ring. Chlorine, being an electron-donating group, directs substitution to the ortho and para positions.

Answer 1

The Correct Option is C

When chlorobenzene is reacted with concentrated nitric acid (HNO3), a nitration reaction takes place. This is an electrophilic aromatic substitution reaction, where the nitronium ion (\( \text{NO}_2^+ \)) generated from the nitric acid acts as the electrophile. The nitration occurs predominantly at the positions that are ortho and para to the chlorine atom. Chlorine, being an electron-donating group via resonance, activates the benzene ring towards electrophilic substitution. However, the electron-donating nature of chlorine causes the reaction to occur more readily at the ortho and para positions relative to the chlorine group. Thus, the product of this reaction is a mixture of ortho and para nitro chloro benzene.
Step 1: Reaction mechanism - The nitronium ion (\( \text{NO}_2^+ \)) attacks the benzene ring. - The chlorine group directs the attack to the ortho and para positions relative to itself due to its electron-donating resonance effect.
Step 2: Conclusion The reaction of chlorobenzene with concentrated nitric acid gives a mixture of ortho and para nitro chloro benzene. Thus, the correct answer is \( \boxed{\text{Mixture of ortho and para nitro benzene}} \).