Question

an optically active 2-chlorobutane reacts with NaI to give optically inactive product Why

Answer 1

Actually, reaction of NaI with 2-chlorobutane favors SN1 mechanism in which the iodide ion attacks on either of the sides resulting in a mixture of product, one at the same configuration as chloride ion is and another at opposite configuration i.e. on opposite side of chloride ion and so the two products forms a (±) mixture known as recemic mixture, which does not rotate polarized light and hence the recemic product obtained is optically inactive.