Question

Phenol on reaction with aqueous solution of bromine gives

• A. o-Bromophenol
• B. m-Bromophenol
• C. p-Bromophenol
• D. 2,4,6-tribromophenol

Hint:

Phenol reacts with bromine water very easily because the \(-\text{OH}\) group strongly activates the ring. So bromination usually gives: \[ \text{2,4,6-tribromophenol} \] as the major product.

Answer 1

The Correct Option is D

Concept:
Phenol contains the \(-\text{OH}\) group attached to a benzene ring. The \(-\text{OH}\) group strongly activates the benzene ring and directs incoming electrophiles to the ortho and para positions. Because of this strong activating effect, bromination of phenol with bromine water occurs very easily and leads to substitution at all the activated positions. ip

Step 1: Understand the effect of the \(-\text{OH}\) group in phenol.
The lone pair of electrons on oxygen gets involved in resonance with the benzene ring. As a result, electron density increases mainly at the ortho and para positions. Therefore, bromine attacks these positions very easily. ip

Step 2: See what happens with bromine water.
When phenol reacts with aqueous bromine solution, bromination is very fast and does not stop at only one substitution. The three positions activated strongly are: \[ 2,\ 4,\ \text{and}\ 6 \] So the product formed is: \[ \text{2,4,6-tribromophenol} \] ip

Step 3: Write the final product clearly.
The reaction can be represented as: \[ \text{Phenol} + 3\text{Br}_2 \rightarrow \text{2,4,6-tribromophenol} + 3\text{HBr} \] ip Hence, the correct answer is:
\[ \boxed{(D)\ \text{2,4,6-tribromophenol}} \]