Finkelstein reaction.

Explanation

### Step-by-Step Solution for Finkelstein Reaction

1. **Understanding the Finkelstein Reaction**:
The Finkelstein reaction is a halogen exchange reaction where an alkyl halide (typically a chloride or bromide) is converted into a higher halide (iodide) using sodium iodide (NaI) in a polar aprotic solvent like acetone.

2. **Starting Materials**:
- You need an alkyl halide (R-Cl or R-Br).
- Sodium iodide (NaI) as the iodide source.
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