Pinacol Rearrangement: 1,2‑Shift to Make Carbonyls (Mechanism + Migration Rules)

Learn the pinacol rearrangement: protonation, water loss, 1,2-shift, and carbonyl formation. Predict which group migrates and why.

• Reaction: Vicinal diol → carbonyl (often ketone)
• What it does: Rearranges diols under acid to give carbonyl compounds
• Typical reagents: Strong acid (H2SO4, HCl)
• Key intermediate: Carbocation adjacent to oxygen
• Driving force: Formation of stable carbonyl; loss of water
• Exam type: Rearrangements
• Exam type: Predict product