Identify the correct reactivity order for the S _ N 2 reaction of the following substituted cyclohexyl chlorides: (I) (II) (III)

Step-by-step solution

In conformationally locked substituted cyclohexanes, the rate of the S _ N 2 reaction depends on the steric hindrance encountered by the incoming nucleophile and the leaving group during the transition state. In structure (I), the bulky tert-butyl group locks the ring such that the chlorine atom is in the axial position. The nucleophile attacks from the backside, which is the equatorial direction. This trajectory is relatively unhindered, making the S _ N 2 reaction fast. In structure (II), the chlorine atom is in