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Allylic and benzylic halides react readily by SN1 because:
AThey are not affected by the solvent
BThey have F as the leaving group
CThey are large molecules
DThe carbocations formed (allyl, benzyl) are stabilised by resonance with the adjacent π system
Answer & Solution
Correct answer: D. The carbocations formed (allyl, benzyl) are stabilised by resonance with the adjacent π system
**Allylic (CH₂=CH-CH₂-X) and benzylic (Ph-CH₂-X)** halides ionise very readily because the resulting **allyl/benzyl carbocations are resonance-stabilised** (delocalised over the adjacent C=C or aromatic ring). Hence high reactivity in SN1.
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