Mesitylene is prepared from :

Options

A. `CH_(3)CHO` and conc. `HNO_(3)`
B. `CH_(3)COCH_(3)` and conc. `H_(2)SO_(4)`
C. `CH_(3)COCH_(3)` and conc. `HCl`
D. `CH_(3)CHO` and conc. `H_(2)SO_(4)`.

Explanation

To prepare mesitylene, we start with acetone and use sulfuric acid as a catalyst. Here’s a step-by-step breakdown of the process:

### Step-by-Step Solution:

1. **Identify the Starting Material**:
- The starting material for the preparation of mesitylene is acetone, which has the chemical formula \( \text{CH}_3\text{COCH}_3 \).

2. **Understand the Reaction Conditions**:
- The reaction requires concentrated sulfuric acid (\( \text{H}_2\text{SO}_4 \)) and hydrochloric acid (\( \text{HCl} \)).
- The reaction is conducted under specific conditions of pressure and temperature, typically between 100°C to 200°C.

3. **Reaction Mechanism**:
- When acetone is treated with sulfuric acid, it undergoes a process called condensation.
- In this process, two molecules of acetone can combine, leading to the formation of mesitylene, which is \( \text{C}_6\text{H}_{12} \) or \( \text{(CH}_3)_3\text{C}_6\text{H}_3 \).

4. **Formation of Mesitylene**:
- The reaction can be summarized as:
\[ 3 \text{CH}_3\text{COCH}_3 \xrightarrow{\text{H}_2\text{SO}_4, \text{HCl}} \text{C}_6\text{H}_{12} + \text{by-products} \]
- The by-products are typically water and other small molecules, which are removed during the reaction.

5. **Conclusion**:
- Therefore, mesitylene is prepared from acetone in the presence of concentrated sulfuric acid and hydrochloric acid under heat and pressure.

### Final Answer:
Mesitylene is prepared from acetone (\( \text{CH}_3\text{COCH}_3 \)) using concentrated sulfuric acid (\( \text{H}_2\text{SO}_4 \)).

---