See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Carbocation Stability Analysis **Step 1: Identify carbocation types** - (1) Tropylium cation ($C_7H_7^+$) — aromatic 7-membered ring - (2) Cyclopropenyl cation — aromatic 3-membered ring - (3) Benzyl cation ($C_6H_5CH_2^+$) — allylic/benzylic - (4) Allyl cation ($CH_2=CH-CH_2^+$) — allylic **Step 2: Apply aromaticity criterion** Aromatic carbocations are exceptionally stable due to $4n+2$ π-electron delocalization: - Tropylium has 6 π-electrons (aromatic, Hückel rule satisfied) - Cyclopropenyl has 2 π-electrons (aromatic) **Step 3: Compare aromatic cations** The **tropylium cation** (option 1) is most stable because: - It has full aromatic character with 6 π-electrons in a symmetric 7-membered ring - Positive charge is delocalized equally over all 7 carbons - Resonance stabilization is maximum The cyclopropenyl cation, while aromatic, has only 2 electrons and weaker stabilization. Benzyl and allyl cations lack true aromaticity. **Answer: Option (1) — Tropylium cation is most stable**