Carbocation Rearrangements: The Shortcut to Predicting ‘Surprise’ Products
Learn when carbocations rearrange (1,2‑hydride/alkyl shifts, ring expansions), how to spot them instantly, and how they change major products in SN1/E1 and additions.
When to expect: Any mechanism with a carbocation intermediate (SN1, E1, some additions).
Common shifts: 1,2‑hydride shift; 1,2‑alkyl shift (methyl shift); ring expansion (e.g., 5→6)
Driving force: Formation of a more stable carbocation (3° > 2° > 1°; resonance-stabilized)
Timing: Rearrangement occurs before nucleophile capture/elimination