Benzene can be converted to isopropyl benzene (Cumene) by the following reagent.

Options

A. `CH_(3) CH_(2) CH_(2)` Cl + Anhy. `AlCl_(3)`
B. `CH_(3)–CH = CH_(2)` + Anhy.` AlCl_(3)+ HCl`
C. Both of the above
D. none of these

Answer

To convert benzene to isopropyl benzene (cumene), we can utilize the Friedel-Crafts alkylation reaction. Here’s a step-by-step solution:

### Step 1: Identify the Reagents
We need to select a suitable alkyl halide and a Lewis acid catalyst. In this case, we can use either n-propyl chloride or propene in the presence of anhydrous AlCl3.

### Step 2: Reaction with n-Propyl Chloride
1. **Formation of Carbocation**:
- When n-propyl chloride (CH3CH2CH2Cl) reacts with anhydrous AlCl3, it forms a 1-degree carbocation (CH3CH2CH2^+).
- The reaction can be represented as:
\[ \text{CH}_3\text{CH}_2\text{CH}_2\text{Cl} + \text{AlCl}_3 \rightarrow \text{CH}_3\text{CH}_2\text{CH}_2^+ + \text{AlCl}_4^- \]

2. **Hydride Shift**:
- The 1-degree carbocation can undergo a hydride shift to form a more stable 2-degree carbocation (CH3CH^+(CH3)).
- The reaction can be represented as:
\[ \text{CH}_3\text{CH}_2\text{CH}_2^+ \rightarrow \text{CH}_3\text{CH}^+(CH_3) \]

### Step 3: Electrophilic Attack on Benzene
3. **Benzene Reaction**:
- The 2-degree carbocation will now react with benzene. The π bond in benzene will break, allowing the carbocation to form a bond with one of the carbon atoms in benzene.
- This can be represented as:
\[ \text{C}_6\text{H}_6 + \text{CH}_3\text{CH}^+(CH_3) \rightarrow \text{C}_6\text{H}_5\text{C}(CH_3)^+ \]

### Step 4: Deprotonation
4. **Formation of Cumene**:
- The AlCl4^- will abstract a proton from the benzene ring, leading to the formation of cumene (isopropyl benzene) and regenerating AlCl3.
- The final reaction can be represented as:
\[ \text{C}_6\text{H}_5\text{C}(CH_3)^+ + \text{AlCl}_4^- \rightarrow \text{C}_6\text{H}_5\text{C}(CH_3) + \text{HCl} + \text{AlCl}_3 \]

### Conclusion
Thus, the overall reaction leads to the formation of isopropyl benzene (cumene) from benzene using n-propyl chloride and anhydrous AlCl3.