Which equation represents an example of Friedel - Crafts reaction?

Options

A. `C_6H_6+C_2H_5Cl overset(AlCl_3)rarrC_6H_5C_2H_5+HCl`
B. `C_2H_5OH+HCloverset(ZnCl_2)rarrC_2H_5Cl+H_2O`
C. `C_2H_5Cl+CH_3COCloverset(AlCl_3)rarrC_6H_5COCH_3+Cl_2`
D. `C_2H__5Br+Mgoverset("ether")rarrC_2H_5MgBr`

Answer

To determine which equation represents an example of a Friedel-Crafts reaction, we need to understand what a Friedel-Crafts reaction is and analyze the given options.

### Step-by-Step Solution:

1. **Understanding Friedel-Crafts Reaction**:
- Friedel-Crafts reactions are a type of electrophilic aromatic substitution. They involve the introduction of an alkyl or acyl group into an aromatic ring (like benzene) using an alkyl halide or acyl chloride in the presence of a Lewis acid catalyst (like aluminum chloride, AlCl3).

2. **Analyzing the Options**:
- **Option 1**: Benzene + C2H5Cl in the presence of AlCl3 → C6H5C2H5 + HCl
- This reaction involves benzene (an aromatic compound) and an alkyl halide (C2H5Cl) with AlCl3 as a catalyst. The ethyl group (C2H5) is introduced into the benzene ring, which is characteristic of Friedel-Crafts alkylation. Therefore, this is a Friedel-Crafts reaction.

- **Option 2**: C2H5OH + HCl, ZnCl2 → C2H5Cl + H2O
- This reaction does not involve an aromatic compound, so it cannot be a Friedel-Crafts reaction.

- **Option 3**: C2H5Cl + CH3COCl → C6H5COCH3 + Cl2
- This reaction is incorrectly formulated and does not involve an aromatic system. Therefore, it is not a Friedel-Crafts reaction.

- **Option 4**: C2H5Br + Mg → C2H5MgBr
- This reaction describes the formation of a Grignard reagent and does not involve an aromatic compound, so it is not a Friedel-Crafts reaction.

3. **Conclusion**:
- After analyzing all options, **Option 1** is the only reaction that represents a Friedel-Crafts reaction, specifically Friedel-Crafts alkylation.

### Final Answer:
The equation that represents an example of a Friedel-Crafts reaction is **Option 1**: Benzene + C2H5Cl in the presence of AlCl3 → C6H5C2H5 + HCl.