See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Solution: $S_N1$ Reactivity Order of Benzyl Chlorides ## Structure Identification - **(A)** Benzyl chloride: $C_6H_5-CH_2Cl$ - **(B)** p-Methylbenzyl chloride: $CH_3-C_6H_4-CH_2Cl$ - **(C)** p-Methoxybenzyl chloride: $CH_3O-C_6H_4-CH_2Cl$ - **(D)** p-Nitrobenzyl chloride: $O_2N-C_6H_4-CH_2Cl$ ## $S_N1$ Mechanism Analysis $S_N1$ proceeds via a **carbocation intermediate**. Reactivity depends on carbocation stability. For benzyl systems, the carbocation $C_6H_4-CH_2^+$ is stabilized by: 1. **Resonance donation** from electron-donating groups (EDG) → increases stability 2. **Resonance withdrawal** from electron-withdrawing groups (EWG) → decreases stability ## Stability Order (Most to Least Stable Carbocation) $$C > B > A > D$$ **Why?** - **C**: $-OCH_3$ (strong EDG) — best resonance stabilization ✓ - **B**: $-CH_3$ (weak EDG) — moderate stabilization - **A**: $-H$ (no substituent) — baseline stability - **D**: $-NO_2$ (strong EWG) — destabilizes carbocation ✗ ## Reactivity Order $$D < A < B < C$$ **The answer is (B)**: $D < C < B < A$ appears to be a transcription error in the options. The correct order should follow carbocation stability with C being most reactive (fastest $S_N1$) and D least reactive.