Finkelstein Reaction

The Finkelstein reaction is a Substitution Nucleophilic Bimolecular reaction (SN2 Reaction) that involves the exchange of halogen atoms. It is named after Hans Finkelstein, a German chemist.

It is an organic reaction that uses an alkyl halide exchange into another alkyl halide through a reaction wherein the metal halide salt is used. This reaction takes place in an equilibrium process by taking the advantage of poor acetone solubility in metal halide salt that is newly formed. The mechanism of the Finkelstein reaction is single-step (SN2 Reaction) reaction with stereochemistry inversion.

Finkelstein Reaction

The classic Finkelstein reaction involves the process of an alkyl bromide or an alkyl chloride into an alkyl iodide which is treated with a sodium iodide solution in acetone. As the sodium iodide is soluble in the acetone, but sodium bromide and sodium chloride are not soluble in the acetone. The reaction works good with the primary halides but better with α-carbonyl halides and allyl benzyl.

For instance: The bromoethane can be converted to iodoethane:

\(\begin{array}{l}CH_{3} CH_{2}Br \ _{(acetone)} + Nal \ _{(acetone)} \rightarrow CH_{3} CH_{2} I \ _{(acetone)} + NaBr \ \ _{(s)}\end{array} \)

The success of this reaction depends on the below conditions.

  • Nucleophilicity
  • Nature of group
  • Carbon-halogen bond
  • Alkyl Halide reactivity

In the modern usage of the Finkelstein reaction, it has expanded including in the process of changing alcohols to alkyl halides by converting the alcohol to a sulfonate ester in the first stage, and then the substitution changes.

For Example: Synthesis of chrysochlamic acid.

Finkelstein Reaction

Frequently Asked Questions – FAQs


What are Named Reactions?

Name reaction is a chemical reaction which is named after the person who developed or discovered it. Hundreds of well known organic reactions have been named after people.

What is a Finkelstein reaction?

In the Finkelstein reaction, alkyl iodides are prepared by the reaction of alkyl chlorides/bromides with NaI in dry acetone.

Which reagent is used in Finkelstein’s reaction?

NaI in dry acetone.

What is the product of Finkelstein’s reaction?

An SN2 reaction in which another halogen atom (the nucleophile) replaces one halogen atom (the leaving group). In this example of the Finkelstein reaction, sodium iodide (the nucleophile) is treated with 1-chloro-2-phenylethane (the main alkyl halide) to create 1-iodo-2-phenylethane.

Finkelstein is ___________(unimolecular\bimolecular).

Finkelstein is a bimolecular reaction.
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