Question

Which of the following compounds will not give azo coupling reaction with benzene diazonium chloride?

• A. Nitrobenzene
• B. Aniline
• C. o-Toluidine
• D. Phenol

Hint:

Azo coupling reactions require electron-donating groups on the benzene ring. Electron-withdrawing groups, like -NO₂, inhibit the reaction.

Answer 1

The Correct Option is A

In the azo coupling reaction, the presence of an electron-donating group on the aromatic ring is necessary for the coupling to occur with the diazonium ion. Nitrobenzene is an electron-withdrawing group, which inhibits the coupling reaction.
Step 1: Understanding Azo Coupling.
Azo coupling typically occurs when an electron-donating group, such as -NH₂ or -OH, is present on the benzene ring. These groups make the ring more reactive towards the electrophilic diazonium ion.
Step 2: Evaluate the compounds.
- Nitrobenzene: Nitro groups (-NO₂) are electron-withdrawing and will not participate in the coupling reaction.
- Aniline: Aniline has an amino group (-NH₂), an electron-donating group, and will participate in the reaction.
- o-Toluidine: o-Toluidine has a methyl group (-CH₃), which is electron-donating, and will also undergo the reaction.
- Phenol: Phenol has a hydroxyl group (-OH), which is also electron-donating, and will undergo coupling with the diazonium ion.
Step 3: Conclusion.
Thus, nitrobenzene will not give the azo coupling reaction.
Final Answer: \[ \boxed{\text{The correct answer is Nitrobenzene.}} \]