What is the product of the reaction of $(R)\text{-2-iodobutane}$ with sodium iodide in acetone (Finkelstein reaction)?

Solution

1. The Finkelstein reaction involves the exchange of halide ions via an ${\text{S}}_{\text{N}}2$ mechanism.
2. The ${\text{S}}_{\text{N}}2$ mechanism proceeds with inversion of configuration at the chiral center.
3. As the reaction proceeds, the concentration of the inverted product increases.
4. Since the reaction is reversible, the continuous inversion leads to the formation of a racemic mixture at equilibrium.
5. Hence the answer is (C).