See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Solution: Comparing Stability of First Intermediates The question asks which reaction pair produces a **less stable first intermediate**. I need to identify the intermediate in each case and evaluate relative stability. ## Analysis of Each Option: **(a) $CF_3-H_2C^{\square}$ & $CH_3-CH_2^{\square}$** - First intermediate: $CF_3CH_2^+$ (carbenium) vs $C_2H_5^+$ (ethyl cation) - $CF_3$ is highly electron-withdrawing → destabilizes the cation - $CH_3$ is electron-donating → stabilizes the cation - The $CF_3CH_2^+$ is less stable here **(b) Benzenium ion vs Toluenemethyl cation** - First intermediate: Benzene $\pi$-complex or resonance-stabilized cation - Aryl cations are extremely unstable; primary benzylic cations are moderately stable - Comparison is unfavorable for benzene cation formation **(c) Tropylium ion ($C_7H_7^+$) vs Tropylium ion ($C_7H_7^+$)** - **Both form the SAME intermediate: the tropylium cation** - The tropylium ion is **exceptionally stable** (aromatic, 6 $\pi$-electrons) - This 7-membered ring cation is among the most stable carbocations known - Since both reactions produce identical, highly stable intermediates, this is the answer **(d) Benzyl chloride vs meta-chlorobenzyl chloride** - Both form benzylic cations with different substituent effects - Chlorine is deactivating but meta-position has minimal conjugative effect ## Conclusion: **Option (c) is correct** because both reactions form the **tropylium cation** ($C_7H_7^+$), which is an aromatic, exceptionally stable intermediate. The question tests understanding that identical intermediates are produced, making this pair special among the options.