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

For azo coupling to occur with a diazonium ion, the aromatic ring must possess an electron-donating group. Nitrobenzene, featuring an electron-withdrawing nitro group, will therefore not undergo this coupling reaction.
Step 1: Understanding Azo Coupling.
Azo coupling is facilitated by the presence of electron-donating groups, such as -NH₂ or -OH, on a benzene ring, increasing its reactivity towards electrophilic diazonium ions.
Step 2: Evaluate the compounds.
- Nitrobenzene: The electron-withdrawing nitro group (-NO₂) prevents participation in the coupling reaction.
- Aniline: The electron-donating amino group (-NH₂) enables participation.
- o-Toluidine: The electron-donating methyl group (-CH₃) allows participation.
- Phenol: The electron-donating hydroxyl group (-OH) permits coupling with the diazonium ion.
Step 3: Conclusion.
Consequently, nitrobenzene will not yield the azo coupling reaction.

Final Answer: \[\boxed{\text{The correct answer is Nitrobenzene.}}\]