See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# H shift vs CH₃ shift in Carbocation Rearrangement **Key Principle:** H shift is preferred over CH₃ shift when it produces a more stable carbocation. ## Analysis of Each Option: **(A)** Secondary carbocation (tert-butyl cation) - H shift → secondary carbocation (same stability) - CH₃ shift → secondary carbocation (same stability) - Both shifts are equivalent; no preference ✗ **(B)** Tertiary carbocation with secondary neighbor - H shift → tertiary carbocation (more stable) - CH₃ shift → tertiary carbocation (same as H shift) - No clear preference for H shift ✗ **(C)** Secondary carbocation with phenyl group attached - **H shift** → tertiary carbocation (phenyl stabilizes via resonance) - **CH₃ shift** → secondary carbocation (less stable) - H shift produces the **more stable carbocation** ✓ The phenyl group is a strong electron-donating group through resonance (hyperconjugation and aromatic stabilization). When H shifts, the positive charge develops on the carbon bearing the phenyl substituent, making it tertiary and resonance-stabilized. This is significantly more stable than a secondary carbocation formed by CH₃ shift. **Answer: (C)**