How will you convert benzoic acid into benzaldehyde ?

Explanation

To convert benzoic acid into benzaldehyde, we can follow a two-step process involving the use of phosphorus pentachloride (PCl5) and the Lindlar's catalyst. Here’s a step-by-step breakdown of the conversion:

### Step 1: Conversion of Benzoic Acid to Benzoyl Chloride

1. **Starting Material**: Begin with benzoic acid (C6H5COOH).

2. **Reagent Addition**: Add phosphorus pentachloride (PCl5) to benzoic acid. PCl5 acts as a chlorinating agent.

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