Optically active 2-iodo butane on treatment with `NaI` in acetone gives a product which does not show optical activity. Explain briefly.

Explanation

Optically active 2-iodobutane on treatment with NaI in acetone undergoes racemization and hence the product does not show optical activity as explained below:
When optically active 21-iodobutane (I) is treated with `I^(-)` ion, it undergoes Walden inversion (`S_(N)2` raction) to give 2-iodobutane (II) which is the enantiomer of (I). Now 2-iodobutane (II) undergoes Walden inversion to give enantiomer (I). As a result of repetition of these two Walden inversion, ultimately a 50:50 mixture of the two enantiomers is obtained