Finkelstein reaction
Alkyl iodides are made by heating an alkyl chloride or bromide with sodium iodide in dry acetone.
BromoethaneCH₃CH₂BrHaloalkane - Step 1
NaI, dry acetone
IodoethaneCH₃CH₂IHaloalkane
How it works
- Iodide displaces chloride or bromide by SN₂ attack.
- NaCl or NaBr is insoluble in acetone and precipitates.
- Removal of the precipitate drives the equilibrium to the alkyl iodide.
What it makes
Alkyl iodides from alkyl chlorides or bromides.
Where it fails
Dry acetone is essential. It works best for primary halides.
Class 12, Chapter 6 Haloalkanes and Haloarenes
Finkelstein reaction: quick answers
Why is acetone used in the Finkelstein reaction?
NaI dissolves in acetone but NaCl and NaBr do not, so they precipitate and push the reaction forward.
What is the mechanism?
SN2 substitution of the halide by iodide.
Can it make alkyl fluorides?
No. Alkyl fluorides are made by the Swarts reaction.