Halogen Exchange (finkelstein)
Mediumchemistry
Finkelstein reaction converts R–Cl to R–I using NaI in acetone because:
Select the correct option:
Solution
Incorrect! Answer:
NaCl precipitates driving reaction forward
- The Reaction: R−Cl+NaI→acetoneR−I+NaCl.
- Nucleophilicity: Iodide is a good nucleophile, but the reaction is technically reversible.
- Solubility Logic: Sodium Iodide (NaI) is soluble in acetone, but Sodium Chloride (NaCl) and Sodium Bromide (NaBr) are insoluble in acetone.
- 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).
- Utility: This is the primary method for synthesizing alkyl iodides, which are hard to prepare by direct iodination.
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About This Question
- Subject
- chemistry
- Chapter
- halogen organics
- Topic
- halogen exchange (finkelstein)
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
NaCl precipitates driving reaction forward
- The Reaction: R−Cl+NaI→acetoneR−I+NaCl.
- Nucleophilicity: Iodide is a good nucleophile, but the reaction is technically reversible.
- Solubility Logic: Sodium Iodide (NaI) is soluble in acetone, but Sodium Chloride (NaCl) and Sodium Bromide (NaBr) are insoluble in acetone.
- 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).
- Utility: This is the primary method for synthesizing alkyl iodides, which are hard to prepare by direct iodination.
This medium difficulty chemistry question is from the chapter halogen organics, covering the topic of halogen exchange (finkelstein). It appeared in the 2025 exam.
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