Which of the following reactants is used for the preparation of ethyl benzene, where anhyd. `AlCl_(3)` is a catalyst?

Options

A. `CH_(3) .CH_(2) OH +C_(6) H_(6)`
B. `CH_(3) - CH= CH_(2) +C_(6) H_(6)`
C. `H_(2) C= CH_(2) +C_(6) H_(6)`
D. `CH_(3)- CH_(3) + C_(6) H_(6)`

Explanation

To prepare ethylbenzene using anhydrous AlCl₃ as a catalyst, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reaction Type**:
The preparation of ethylbenzene from benzene involves a Friedel-Crafts alkylation reaction. This reaction requires a catalyst, which in this case is anhydrous AlCl₃.

2. **Identify the Reactants**:
The reactants needed for this reaction are benzene (C₆H₆) and an alkyl halide. For the preparation of ethylbenzene, we use ethylene (C₂H₄) or an ethyl halide such as bromoethane (C₂H₅Br).

3. **Write the Reaction Equation**:
The general reaction can be represented as:
\[ \text{C}_6\text{H}_6 + \text{C}_2\text{H}_5\text{Br} \xrightarrow{\text{AlCl}_3} \text{C}_6\text{H}_5\text{C}_2\text{H}_5 + \text{HBr} \]
Here, benzene reacts with bromoethane in the presence of AlCl₃ to form ethylbenzene and hydrogen bromide.

4. **Mechanism of the Reaction**:
- The AlCl₃ catalyst helps in generating a more reactive electrophile from the alkyl halide (bromoethane).
- The ethyl cation (C₂H₅⁺) is formed, which then acts as an electrophile.
- The benzene ring donates its electrons to the ethyl cation, leading to the formation of ethylbenzene.

5. **Final Product**:
The final product of this reaction is ethylbenzene (C₆H₅C₂H₅).

### Conclusion:
Thus, the reactants used for the preparation of ethylbenzene with anhydrous AlCl₃ as a catalyst are benzene and bromoethane (or ethylene).

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