Identify the correct order of reactivity for the following compounds towards the S _ N 1 reaction. (I) (II) (III)

Step-by-step solution

The reactivity of alkyl halides towards the S _ N 1 reaction depends on the stability of the intermediate carbocation formed. Compound (III) forms a secondary cyclohexyl carbocation. This carbocation can achieve the required planar sp^2 geometry and is relatively stable. Compounds (I) and (II) form carbocations at the bridgehead position. According to Bredt's rule, bridgehead carbocations are highly unstable because the rigid bicyclic framework prevents the carbon atom from achieving a planar sp^2 hybridization, le