I have the following SN2 reaction, in an acetone:
1,4-dichlorohexane (1 mol) reacting with NaI (1 mol) to form 4-chloro-1-iodohexane and NaCl.

However, chloride ions are stronger nucleophiles than iodide ions in an aprotic solvent and iodide ions are weaker bases than chloride ions. Reactions generally form weaker bases, why does this reaction occur? My text shows it does, but I don't understand why. What am I missing?

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    $\begingroup$ While everybody makes mistakes, it would be preferable that when you copied the question falsely and an answer has already been given, you would ask a new question instead. In the very least you can inform the author of the answer about the changes. $\endgroup$ – Martin - マーチン Aug 1 '16 at 10:19

Acetone is the key here. The solubility of NaI in acetone is about 50 g in 100 mL while NaCl is virtually insoluble in acetone, thus the reaction is driven towards the alkyliodide due to Le Châtelier’s principle, since NaCl will be precipitating from the reaction. This process is called a Finkestein Reaction. Also see this.


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