Solvolysis And Carbocation Stability

The rate of solvolysis of alkyl halides depends on the stability of the carbocation intermediate formed during the reaction. The more stable the carbocation, the faster the solvolysis reaction. The relative stability of the carbocations is influenced by the type of carbon and the substituent groups attached to it. - (A) Cyclohexyl bromide forms a less stable carbocation, so its rate of solvolysis is slower.
- (B) Benzyl bromide forms a highly stabilized carbocation due to resonance with the benzene ring, leading to a faster solvolysis.
- (C) Phenylmethyl bromide also forms a stable carbocation but less stable than the benzyl carbocation.
- (D) Allyl bromide forms a very stable carbocation due to resonance, making it the most reactive in solvolysis. Thus, the correct ascending order is .

The given compound undergoes a reaction where: - On heating with and , it gives 2,4-dimethyl pentane, which is consistent with the presence of a double bond at the second position of a heptane chain.
- Aromatization gives toluene, indicating a benzene ring formation.
- Cyclisation gives methyl cyclohexane, further supporting the structure of a hept-2-ene compound.
Thus, compound is Hept-2-ene.
Final Answer: Hept-2-ene

Concept: The rate of reactions depends on the stability of the carbocation intermediate.
Step 1:Check Statement I} Benzyl chloride forms a benzyl carbocation: This carbocation is resonance stabilized by the benzene ring. Ethyl chloride forms an ethyl carbocation: which is much less stable. Thus benzyl chloride reacts faster in . Hence Statement I is true.
Step 2:Check Statement II} Ethyl carbocation is stabilized only by hyperconjugation. Benzyl carbocation is stabilized by resonance with the aromatic ring, which is stronger. Thus ethyl carbocation is less stabilized than benzyl carbocation. Hence Statement II is also true.