See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Solution: Benzyne Formation from Various Precursors **Step 1: Analyze compound (A) → (B)** Chlorobenzene with $NaNH_2$ undergoes nucleophilic aromatic substitution to form **aniline (B)**, where $-Cl$ is replaced by $-NH_2$. **Step 2: Analyze (B) → (C)** Heating aniline causes diazotization followed by loss of $N_2$ gas, forming a **benzyne intermediate**. The $-NH_2$ group is converted to $-N_2^+$ and eliminated as $N_2$ upon heating. **Step 3: Mechanism of benzyne formation** Benzyne ($C_6H_4$) is a highly reactive species with a strained triple bond character. It's generated by: - Nucleophilic aromatic substitution (from halobenzenes with strong bases) - Thermal decomposition of arenediazonium salts (from anilines) **Step 4: Analyze (C) → (D)** Chlorobenzene with $NaNH_2$ directly produces benzyne through the **elimination mechanism**: $$\text{Cl-C}_6H_4\text{-Br} + NaNH_2 \rightarrow \text{benzyne intermediate} \rightarrow \text{benzene (after H abstraction)}$$ **Conclusion:** - **(A)** gives benzyne ✓ - **(B)** gives benzyne ✓ - **(C)** gives benzyne ✓ **Answer: (D) All** — All three pathways (from halobenzenes, anilines, and mixed dihalobenzenes) can generate benzyne intermediates and ultimately produce benzene through hydrogen abstraction or nucleophilic capture.