Illustrated Glossary of Organic Chemistry

Pinacol rearrangement (pinacol-pinacolone rearrangement): Rearrangement of a vicinal diol via carbon group migration to produce a ketone. Often with acid catalysis.

When treated with aqueous sulfuric acid, 2-methyl-3-phenylbutane-2,3-diol (a vicinal diol) rearranges into 3-methyl-3-phenylbutan-2-one (a ketone). Carbocation rearrangement occurs when a methyl group migrates.