Question

Which one of the following reactions is NOT possible?

• A.
• B.
• C.
• D.

Answer 1

Answer: (B)

Answer 2

Step 1: Analyze each reaction
1. Reaction (1):
The reaction involves the cleavage of the ether bond ($\text{C} - \text{OCH}_3$) by $\text{HBr}$, producing phenol ($\text{C}_6\text{H}_5 - \text{OH}$). This reaction is possible due to the nucleophilic substitution mechanism.
2. Reaction (2):
The reaction involves the conversion of phenol ($\text{C}_6\text{H}_5 - \text{OH}$) to chlorobenzene ($\text{C}_6\text{H}_5 - \text{Cl}$) by $\text{HCl}$. However, this reaction is \textbf{NOT} possible because the hydroxyl group in phenol is directly attached to the benzene ring, and it does not undergo nucleophilic substitution to form $\text{C}_6\text{H}_5 - \text{Cl}$. The lone pair on oxygen in phenol makes the $-\text{OH}$ group resistant to substitution by $\text{HCl}$.
3. Reaction (3):
The reaction involves the hydrolysis of chlorobenzene ($\text{C}_6\text{H}_5 - \text{Cl}$) under high temperature and pressure in the presence of $\text{NaOH}$. This reaction is possible via nucleophilic aromatic substitution, producing phenol ($\text{C}_6\text{H}_5 - \text{OH}$).
4. Reaction (4):
The reaction involves the electrophilic substitution of anisole ($\text{C}_6\text{H}_5 - \text{OCH}_3$) with chlorine in the presence of $\text{AlCl}_3$. This reaction is possible, producing a mixture of ortho and para substituted products.
Step 2: Conclusion
Among the given reactions, only Reaction (2) is not possible because phenol does not undergo nucleophilic substitution with $\text{HCl}$ to form chlorobenzene.
Final Answer: (2).