sn2 reaction

Question

SN2 reaction is favored by:

RankGuru · Accepted Answer

The **$S_N2$ (Substitution Nucleophilic Bimolecular)** mechanism involves a simultaneous bond-breaking and bond-forming event via a **transition state**.
- The nucleophile attacks from the **back side** (opposite to the leaving group), leading to an **Inversion of Configuration** (Walden Inversion).
- Because the nucleophile must approach the carbon center, the reaction is extremely sensitive to **steric hindrance**.
- **Reactivity Order**: $CH_3X > 1^\circ > 2^\circ \gg 3^\circ$.
- Primary halides are least crowded, offering less resistance to the incoming nucleophile, and thus react most rapidly.

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sn2 reaction

Select the correct option: