# Confusion on the Finkelstein reaction(AKA halogen exhange reaction)

So in the Finkelstein reaction, the iodide ion is supposed to replace another halogen(say chlorine) through SN2 mechanism. But here, Acetone is used, which is a polar aprotic solvent. And in acetone, iodide ion is the weakest nucleophile. So how can it replace the chlorine?

Aren't we better off if we use water or ethanol(which are polar protic solvents) since (I-) acts as the strongest nucleophile?

• Jan 22 at 7:09
• the driving force of Finkelstein is the insolubility of the product halogen salt (KCl for ex) so that it is removed from the reaction. Jan 22 at 7:56
• Iodide would be also be a worse nucleophile in a protic solvent.
– Zhe
Jan 22 at 15:21