Identify the correct reactivity order for the S _ N 1 reaction of the following compounds: (i) (ii) (iii)

Step-by-step solution

The rate of an S _ N 1 reaction is directly proportional to the stability of the carbocation intermediate formed in the rate-determining step. For compound (i), the leaving group is located at a bridgehead position. The resulting bridgehead carbocation is highly unstable due to Bredt's rule, as the rigid bicyclic framework prevents the carbon from adopting the necessary planar sp^2 hybridization. Consequently, compound (i) is the least reactive. For compound (ii), ionization yields a carbocation flanked by two oxyg