Solvolysis And Carbocation Stability

For an SN reaction, the reactivity is influenced by the stability of the carbocation formed during the reaction. The order of reactivity follows the trend: allyl>benzyl>primary.

Let’s analyze the compounds:

- Compound A, C H CH Cl: The benzyl chloride undergoes SN easily due to the resonance stabilization of the benzyl carbocation. It is highly reactive.
- Compound B, C H Cl: This is a simple aryl chloride, and the carbocation formed is not stabilized by resonance as in the case of benzyl chloride, so it is less reactive.
- Compound C, CH =CH–Cl: This is an allyl chloride, which can form a resonance-stabilized carbocation. However, the double bond conjugation decreases its reactivity compared to benzyl chloride.
- Compound D, CH –CH –Cl: This is a primary alkyl chloride, and it forms a primary carbocation, which is the least stable, hence the least reactive. Thus, the order of reactivity towards SN is: