Which of the following can be used as the halide component for Friedel Crafts reaction ?

Options

A. Chlorobenzene
B. Bromobenzene
C. Chlorobenzene
D. Isopropyl chloride

Answer

To determine which of the given compounds can be used as the halide component for a Friedel-Crafts reaction, we need to analyze the reactivity of each compound in the context of electrophile generation.

### Step-by-Step Solution:

1. **Understanding Friedel-Crafts Reaction**:
The Friedel-Crafts reaction involves the alkylation or acylation of an aromatic compound (like benzene) using a halide component and a Lewis acid catalyst (like AlCl3). The halide component must be able to generate a reactive electrophile.

2. **Analyzing the Given Halides**:
Let's consider the halides mentioned in the question: bromobenzene, chlorobenzene, and chloroethene.

- **Bromobenzene (C6H5Br)**:
In bromobenzene, the bromine atom is attached to a benzene ring. The lone pair on the bromine can delocalize into the aromatic system, giving it partial double bond character. This delocalization stabilizes the molecule and makes it less likely to participate in electrophile generation.

- **Chlorobenzene (C6H5Cl)**:
Similar to bromobenzene, chlorobenzene also has a chlorine atom attached to the benzene ring. The lone pair on chlorine can also delocalize into the aromatic system, making it less reactive for electrophile generation.

- **Chloroethene (C2H3Cl)**:
Chloroethene has a double bond between the carbon atoms. The chlorine atom does not have the same resonance stabilization with an aromatic system as the previous compounds. However, it is still not ideal for generating a strong electrophile.

3. **Identifying the Suitable Halide**:
The only compound that can effectively generate an electrophile is **isopropyl chloride (C3H7Cl)**. In isopropyl chloride, the chlorine atom is attached to an alkyl group (isopropyl). When treated with a Lewis acid like AlCl3, the chlorine can be removed, generating a carbocation (the electrophile) that can react with benzene.

4. **Reaction Mechanism**:
- When isopropyl chloride reacts with AlCl3, the chlorine atom leaves, and a carbocation (isopropyl cation) is formed.
- This carbocation can then attack the benzene ring, resulting in the substitution of a hydrogen atom with the isopropyl group.

5. **Conclusion**:
Therefore, the only suitable halide component for the Friedel-Crafts reaction among the options provided is **isopropyl chloride**.

### Final Answer:
**Isopropyl chloride can be used as the halide component for Friedel-Crafts reaction.**

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