See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Solution: 1,2-Shift (Hydride or Alkyl Shift) **What is a 1,2-shift?** A 1,2-shift involves migration of a group (hydride or alkyl) from one carbon to an adjacent carbon, typically to stabilize a carbocation intermediate. **Analysis of each option:** **(A) $(CH_3)_2C^{\oplus}-CH_2$** - Secondary carbocation at the quaternary carbon - A **methyl group (1,2-shift)** from the quaternary C → adjacent C would give: $(CH_3)C^{\oplus}-CH(CH_3)_2$ - This rearranges to a **tertiary carbocation** → **STABILIZES** the structure - This **WILL undergo 1,2-shift** ✓ **(B) $(CH_3)_2C\,CH^{\oplus}-CH_2$ with $H_3^{2\oplus}$** - Hydride attached to the carbocation carbon - A **hydride (1,2-shift)** occurs → gives the starting material back - This **WILL undergo 1,2-shift** ✓ **(C) Cyclohexyl cation with OH and $\oplus$** - Hydroxyl group (oxygen) is a **poor migrating group** due to its high electronegativity - Oxygen preferentially loses bonding electrons and doesn't migrate in 1,2-shifts - This **WILL NOT undergo 1,2-shift** ✗ **Answer: (A) is correct.** Option A will actually **undergo** a 1,2-shift (methyl shift) to form a more stable tertiary carbocation, so it **IS** capable of giving 1,2-shift products. *Note: The question likely asks which will NOT give 1,2-shift, making **(C)** the answer, as OH is not a good migrating group.*