Question

The correct order of reactivity in electrophilic substitution reaction of the following compounds is :

• A. \( B > C > A > D \)
• B. \( D > C > B > A \)
• C. \( A > B > C > D \)
• D. \( B > A > C > D \)

Answer 1

The Correct Option is D

Substituents on the benzene ring of aromatic compounds affect their reactivity in electrophilic substitution reactions. These substituents can either increase (activate) or decrease (deactivate) reactivity and direct the electrophile to particular ring positions.

Consider the following compounds:

1. Compound A: Benzene
2. Compound B: Toluene (methylbenzene)
3. Compound C: Chlorobenzene
4. Compound D: Nitrobenzene

Analysis:

• Toluene (B): The methyl group donates electrons, activating the benzene ring for electrophilic substitution, thus increasing its reactivity compared to benzene.
• Chlorobenzene (C): Chlorine is electronegative, withdrawing electrons. However, its lone pairs can participate in resonance. This leads to reduced reactivity compared to benzene, but it is less deactivating than nitrobenzene.
• Nitrobenzene (D): The nitro group strongly withdraws electrons, significantly deactivating the benzene ring for electrophilic substitution.

Consequently, the order of reactivity in electrophilic substitution is:

B > A > C > D

This indicates Toluene is the most reactive, followed by Benzene, then Chlorobenzene, and Nitrobenzene is the least reactive.