Question

Identify the product formed when phenol reacts with bromine water.

• A. Bromobenzene
• B. \(o\)-Bromophenol
• C. \(2,4,6\)-Tribromophenol
• D. Chlorobenzene

Hint:

Phenol reacts with bromine water without any catalyst due to the strongly activating \(-OH\) group. The reaction gives \(2,4,6\)-tribromophenol as a white precipitate and is often used as a test for phenol.

Answer 1

The Correct Option is C

Topic: Organic Chemistry - Phenols
Step 1: Understanding the Question:
We are examining the electrophilic aromatic substitution of phenol. The reagent is bromine water (\(Br_2\) in \(H_2O\)).
Step 2: Key Formula or Approach:
Phenol is highly reactive due to the \(+R\) effect of the \(-OH\) group. In aqueous media, phenol ionizes to the phenoxide ion, which is even more reactive.
Step 3: Detailed Explanation:
1. The \(-OH\) group is an ortho and para directing activator.
2. In the presence of water (a polar solvent), the activation is so strong that substitution occurs at all available ortho and para positions simultaneously.
3. The reaction involves three moles of bromine:
\[ C_6H_5OH + 3Br_2 \xrightarrow{H_2O} C_6H_2(Br)_3OH + 3HBr \]
4. The product \(2,4,6\)-tribromophenol forms as a distinct white precipitate.
Step 4: Final Answer:
The product is \(2,4,6\)-tribromophenol.