Cumene `underset("Boil")overset(KMnO_(4))(to)Aoverset(PCl_(5))(to)Boverset(C)(to)` Benzaldehyde
Find "C" :

Options

A. `H_(2)//Pd//BaSO_(4)`
B. CO/HCl/ `AlCl_(3)`
C. `CH_(3)NH_(2)//HCl//AlCl_(3)`
D. `CrO_(3)//Ac_(2)O`

Answer

To solve the problem step by step, we will analyze the transformations of cumene to benzaldehyde through the various reagents mentioned.

### Step 1: Identify the starting compound
- **Starting compound**: Cumene (isopropyl benzene), which has the structure:
\[ \text{C}_6\text{H}_5\text{C}(\text{CH}_3)_2 \]

### Step 2: Reaction with KMnO4
- **Reagent**: KMnO4 (potassium permanganate) in a boiling condition.
- **Reaction**: This reagent is a strong oxidizing agent. When cumene is treated with KMnO4, it undergoes oxidation to form benzoic acid.
- **Product A**: Benzoic acid (\(C_6H_5COOH\)).

### Step 3: Reaction with PCl5
- **Reagent**: PCl5 (phosphorus pentachloride).
- **Reaction**: Benzoic acid reacts with PCl5 to form benzoyl chloride (an acid chloride).
- **Product B**: Benzoyl chloride (\(C_6H_5C(O)Cl\)).

### Step 4: Conversion of benzoyl chloride to benzaldehyde
- **Reagent**: The conversion of benzoyl chloride to benzaldehyde typically involves a reduction process.
- **Reduction Method**: The Rosenmund reduction is used here, which involves the use of hydrogen gas (H2) in the presence of a palladium catalyst supported on barium sulfate (BaSO4).
- **Product C**: Benzaldehyde (\(C_6H_5CHO\)).

### Conclusion
- The compound "C" that is used in the reduction of benzoyl chloride to benzaldehyde is:
- **C**: \(H_2\) in the presence of \(Pd/BaSO_4\) (palladium on barium sulfate).

### Final Answer
- **C**: \(H_2\) with \(Pd/BaSO_4\)

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