alkyl halides

Question

The order of reactivity of alkyl halides in SN1 reaction is:

RankGuru · Accepted Answer

The **$S_N1$ (Substitution Nucleophilic Unimolecular)** mechanism proceeds through the formation of a **carbocation intermediate**.
1. **Step 1 (RDS)**: Formation of carbocation by leaving group departure.
2. **Step 2**: Rapid attack of the nucleophile.
- The rate of reaction depends solely on the stability of the carbocation formed.
- **Stability Order**: $3^\circ$ (Tertiary) $> 2^\circ$ (Secondary) $> 1^\circ$ (Primary) $> CH_3^+$ (Methyl).
- This is due to **inductive effect ($+I$)** and **hyperconjugation** from alkyl groups which disperse the positive charge. Therefore, tertiary halides are most reactive in $S_N1$.

Rank Guru

alkyl halides

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