halogen exchange (finkelstein)

Question

Finkelstein reaction converts R–Cl to R–I using NaI in acetone because:

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1. **The Reaction**: $R-Cl + NaI \stackrel{	ext{acetone}}{	o} R-I + NaCl$.
2. **Nucleophilicity**: Iodide is a good nucleophile, but the reaction is technically reversible.
3. **Solubility Logic**: Sodium Iodide ($NaI$) is soluble in acetone, but Sodium Chloride ($NaCl$) and Sodium Bromide ($NaBr$) are **insoluble** in acetone.
4. **Le Chatelier's Principle**: As $NaCl/NaBr$ forms, it precipitates out of the organic solution. This removal of product from the equilibrium system drives the reaction towards completion (forward direction).
5. **Utility**: This is the primary method for synthesizing alkyl iodides, which are hard to prepare by direct iodination.

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halogen exchange (finkelstein)

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