Illustrated Glossary of Organic Chemistry

Beckmann rearrangement: Treatment of an oxime with aqueous acid results in rearrangement to an amide. (When the oxime is cyclic then the product is a lactam.)

Beckmann rearrangement of cyclohexanone oxime with aqueous sulfuric acid produces caprolactam. The reaction mechanism involves protonation of the oxime hydroxyl group, loss of water with simultaneous bond migration, and tautomerization.