(±)−iodobutane
(±),2−diiodobutane
(R)−iodobutane
(S)−iodobutane
I⁻ is a good nucleophile as well as a good leaving group. Therefore, if (R)-2-iodobutane is treated with NaI, repeated SN2 reactions occur. As a result, eventually a racemic mixture of (±)-2 iodobutane is obtained.