Question

What is the major product formed when phenol reacts with bromine water?

• A. Bromobenzene
• B. 2-bromophenol
• C. 2,4-dibromophenol
• D. 2,4,6-tribromophenol

Hint:

Phenol is highly activating toward electrophilic substitution. With bromine water, it undergoes rapid substitution at the ortho and para positions, producing \(2,4,6\)-tribromophenol as a white precipitate.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
This is a chemical reaction question involving the electrophilic aromatic substitution of phenol in a highly polar solvent (water).
Step 2: Detailed Explanation:
The \( -OH \) group in phenol is a very strong activating group. It increases electron density on the benzene ring through the \( +R \) effect, particularly at the ortho and para positions.
When bromine is used with water (a highly polar solvent), the bromine molecule is easily polarized, and phenol becomes even more reactive because it can lose a proton to form a phenoxide ion in water.
The phenoxide ion is even more activating than the hydroxyl group.
As a result, electrophilic substitution occurs rapidly at all available ortho (2 and 6) and para (4) positions simultaneously.
This leads to the formation of a white precipitate known as 2,4,6-tribromophenol.
Step 3: Final Answer:
The major product is 2,4,6-tribromophenol.