Propanal to propyne

Explanation

To convert propanal (an aldehyde) to propyne (an alkyne), we can follow these steps:

### Step 1: Convert Propanal to 1,1-Dichloropropane
1. **Starting Material**: Propanal (CH3CHO)
2. **Reagent**: Phosphorus pentachloride (PCl5)
3. **Reaction**: When propanal reacts with PCl5, the aldehyde group (–CHO) is converted into a dichloromethyl group (–CCl2). The oxygen is replaced by two chlorine atoms.
4. **Product**: 1,1-Dichloropropane (CH3CHCl2CH2)

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