See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Analysis of Carbocation Stability Upon Heating **Step 1: Identify the reaction mechanism** Upon strong heating, these alkyl/aryl chlorides undergo heterolytic cleavage to form carbocations: $R-Cl \rightarrow R^+ + Cl^-$ **Step 2: Evaluate each carbocation's stability** - **(A) Benzyl carbocation** ($C_6H_5-CH_2^+$): Secondary benzylic carbocation — moderately stabilized by resonance with benzene ring - **(B) Trityl carbocation** ($(Ph)_3C^+$): Tertiary carbocation with exceptional stability from three phenyl groups, but extremely bulky - **(C) Cycloheptatrienyl cation** ($C_7H_7^+$): **Aromatic, 7π-electron Hückel system** — aromatic stability comparable to tropylium ion - **(D) Allylic carbocation**: Allylic system with resonance, but weaker than aromatic stabilization **Step 3: Apply aromaticity criterion** The cycloheptatrienyl cation follows Hückel's rule with $n=1$ ($(4n+2) = 6$ delocalized electrons through the ring), achieving exceptional **aromatic stabilization**. This makes it uniquely stable as a persistent cation. **Answer: (C)** — The cycloheptatrienyl cation's aromatic character provides the most thermodynamic stability, enabling easy formation and persistence upon heating.