benzylic reactivity

Question

Benzylic bromides undergo SN1 faster than alkyl bromides due to:

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1. **Intermediate**: In an $SN1$ reaction, the rate depends on how easily the metal-halogen bond breaks to form a carbocation.
2. **Benzylic System**: In benzyl bromide ($C_6H_5CH_2Br$), the resulting carbocation ($C_6H_5CH_2^+$) is adjacent to a benzene ring.
3. **Resonance**: The positive charge on the methylene carbon is delocalized into the ortho and para positions of the aromatic ring through resonance.
4. **Stability**: This **resonance stabilization** significantly lowers the activation energy for the first step, making benzylic halides exceptionally reactive in $SN1$ processes.

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benzylic reactivity

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