The correct order of rate of solvolysis for the following compounds is (I) Cyclopentadienyl bromide (II) Cycloheptatrienyl bromide (III) Benzyl bromide
Official Solution
Correct Option: (1)
Step 1: Understanding the Concept:
Solvolysis rate in reactions is governed by the stability of the intermediate carbocation. Step 2: Detailed Explanation:
1. Compound II: Forms the tropylium cation, which is cyclic, planar, fully conjugated, and has electrons. It is aromatic and extremely stable.
2. Compound III: Forms the benzyl cation, which is stabilized by resonance with the phenyl ring. It is stable but less so than an aromatic cation.
3. Compound I: Forms the cyclopentadienyl cation. It has electrons in a cyclic planar system, making it anti-aromatic and highly unstable. Step 3: Final Answer:
The order is II > III > I.
