The product obtained when 4-hydroxybenzene sulphonic acid is treated with an excess of bromine water is

Options

A. 2-bromo-4-hydroxybenzene sulphonic acid
B. 2,3-dibromo-4-hydroxybenzene sulphonic acid
C. 2,6-dibromo-4-hydroxybenzene sulphonic acid
D. 2,4,6-Tribromophenol

Answer

To determine the product obtained when 4-hydroxybenzene sulfonic acid is treated with an excess of bromine water, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Structure of 4-Hydroxybenzene Sulfonic Acid**:
- The compound has a benzene ring with a hydroxyl group (-OH) at the para position (4-position) and a sulfonic acid group (-SO3H) also attached to the benzene ring.
- The structure can be represented as:
```
OH
|
C6H4-SO3H
```

2. **Understand the Reactivity with Bromine Water**:
- Bromine water contains Br2, which can dissociate into bromine electrophiles (Br+ and Br-).
- The hydroxyl group (-OH) is an electron-donating group that activates the benzene ring, increasing the electron density at the ortho and para positions relative to the -OH group.

3. **Identify the Positions for Electrophilic Substitution**:
- The activated positions for electrophilic substitution are the ortho (2-position) and para (4-position) relative to the hydroxyl group.
- The sulfonic acid group (-SO3H) is a deactivating group, but since the -OH group is more activating, bromination will preferentially occur at the ortho and para positions.

4. **Perform the Bromination Reaction**:
- When treated with excess bromine water, the -OH group will direct bromination to the ortho and para positions.
- The final product will have bromine atoms substituted at the 2, 4, and 6 positions of the benzene ring.

5. **Draw the Final Structure**:
- The final structure will have three bromine atoms attached to the benzene ring at the 2, 4, and 6 positions, along with the hydroxyl group.
- The structure can be represented as:
```
Br
|
Br-C6H2(OH)-Br
```

6. **Name the Product**:
- The compound is named 2,4,6-tribromophenol, indicating the presence of three bromine substituents on the phenol ring.

### Final Answer:
The product obtained when 4-hydroxybenzene sulfonic acid is treated with an excess of bromine water is **2,4,6-tribromophenol**.

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