Isopropylbenzene can be prepared by :

Options

A. Benzene `+CH_(3)CH=CH_(2)overset(H_(2)SO_(4))rarr`
B. Benzene `+CH_(3)-underset(Cl)underset(|)(CH)-CH_(3)overset(H_(2)SO_(4))rarr`
C. Benzene `+CH_(3)underset(Cl)underset(|)CH-CH_(3)overset(AlCl_(3))rarr`
D. Benzene `+CH_(3)CH_(2)CH_(2)Clunderset(Delta)overset(AlCl_(3))rarr`

Answer

To prepare isopropylbenzene (also known as cumene), we can use several methods. Below is a step-by-step text solution based on the provided information.

### Step-by-Step Solution:

1. **Understanding the Structure of Isopropylbenzene**:
- Isopropylbenzene consists of a benzene ring attached to an isopropyl group (C3H7). The isopropyl group has the structure (CH(CH3)2), meaning it has a central carbon bonded to two methyl groups and one hydrogen.

2. **Method A - Protonation of Alkene**:
- In this method, benzene reacts with an alkene in the presence of sulfuric acid (H2SO4).
- The alkene gets protonated to form a carbocation. For isopropylbenzene, the carbocation formed would be the isopropyl carbocation (C3H7+).
- This carbocation then attacks the benzene ring, leading to the formation of isopropylbenzene.

3. **Method B - Friedel-Crafts Alkylation**:
- In this method, isopropyl chloride (C3H7Cl) reacts with benzene in the presence of a Lewis acid, such as aluminum chloride (AlCl3).
- The Lewis acid helps to generate the isopropyl carbocation from isopropyl chloride.
- The isopropyl carbocation then attacks the benzene ring, forming isopropylbenzene.

4. **Method C - Hydride Shift**:
- In this method, a primary carbocation is formed first, which is less stable.
- A hydride shift occurs, where a hydrogen atom moves from an adjacent carbon to stabilize the carbocation, forming a more stable secondary isopropyl carbocation.
- This secondary carbocation then attacks the benzene ring to yield isopropylbenzene.

5. **Conclusion**:
- Methods A, B, and C successfully yield isopropylbenzene, while other methods may not lead to the desired product.
- Therefore, the correct methods to prepare isopropylbenzene are A, B, and C.

### Final Answer:
Isopropylbenzene can be prepared by methods A, B, and C.

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