Identify the correct decreasing order of reactivity for the following alkyl halides towards the S _ N 2 reaction: (I) (II) (III)

Step-by-step solution

The reactivity of alkyl halides towards the S _ N 2 reaction depends on the steric hindrance around the electrophilic carbon atom. A less sterically hindered carbon allows the nucleophile to attack more easily from the backside. Let us identify the degree of the given alkyl halides: (I) tert-butyl chloride is a tertiary ( 3^ ) alkyl halide. (II) isopropyl chloride is a secondary ( 2^ ) alkyl halide. (III) ethyl chloride is a primary ( 1^ ) alkyl halide. The steric hindrance increases in the order: 1^ Therefore, the