Catalyst used in Rosenmund reduction is `:`

Options

A. `Pd//BaSO_(4)`
B. Zn-Hg couple
C. `Li[AlH_(4)]`
D. `H_(2)//Ni`

Answer

To solve the question regarding the catalyst used in the Rosenmund reduction, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Rosenmund Reduction**:
The Rosenmund reduction is a chemical reaction that involves the reduction of an acyl chloride to an aldehyde using hydrogen gas in the presence of a catalyst.

2. **Identify the Reactants**:
In the case of the Rosenmund reduction, the primary reactant is benzoyl chloride (C6H5C(O)Cl), which is an acyl chloride.

3. **Identify the Catalyst**:
The catalyst used in the Rosenmund reduction is palladium (Pd) supported on barium sulfate (BaSO4). This specific combination allows for selective reduction of the acyl chloride to the corresponding aldehyde without further reduction to an alcohol.

4. **Recognize the Product**:
The product of the Rosenmund reduction of benzoyl chloride is benzaldehyde (C6H5CHO).

5. **Select the Correct Answer**:
From the options provided, the correct catalyst used in the Rosenmund reduction is **Pd in the presence of BaSO4**.

### Final Answer:
The catalyst used in the Rosenmund reduction is **Pd (palladium) in the presence of BaSO4 (barium sulfate)**.

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