Advanced Topic 874 of 1102 Organic Chemistry
Beckmann Rearrangement
Oximes rearrange into amides under acid conditions.
In-depth explanation of Beckmann Rearrangement
The Beckmann rearrangement converts an oxime into an amide under acid conditions. The oxime oxygen is activated by protonation or by a sulfonate, and the group anti to the leaving group migrates from carbon to nitrogen as the leaving group departs. The resulting nitrilium ion is attacked by water and then tautomerizes to the amide. Because the migrating group is determined by the stereochemistry of the oxime, the reaction is stereospecific. It is the industrial route to caprolactam, the monomer of nylon-6.
Going deeper: Beckmann Rearrangement
Key ideas: An oxime (from ketone and NH2OH) rearranges under acid (H2SO4, PCl5) to an amide: the group anti to the leaving OH migrates to nitrogen. Cyclohexanone oxime gives caprolactam, the monomer for nylon 6 (about 5 million tonnes per year). Retention of stereochemistry in the migrating group. Aldoximes may give nitriles by dehydration instead.
Common mistakes and connections: Students migrate the group syn to OH rather than anti, giving the wrong amide. Another error is confusing it with the Hofmann degradation. Links to nylon 6 production, oximes, imine chemistry and electron-deficient nitrogen rearrangements.
Visualization of Beckmann Rearrangement
Acid converts the oxime OH to a leaving group, the group anti to it migrates, and water captures the nitrilium to give the amide. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Cyclohexanone oxime rearranges under acid to give caprolactam, a seven-membered lactam.
Frequently asked questions about Beckmann Rearrangement
What is Beckmann Rearrangement?
Oximes rearrange into amides under acid conditions.
Is Beckmann Rearrangement a beginner, intermediate or advanced topic?
Beckmann Rearrangement is a advanced topic in Organic Chemistry. It builds on beginner and intermediate topics, so review those first if needed.
What should I learn before Beckmann Rearrangement?
Study these earlier topics in Organic Chemistry first: Sharpless Epoxidation, Hydroboration-Oxidation, Baeyer-Villiger Oxidation.
What comes after Beckmann Rearrangement?
The next topics in Organic Chemistry are Pinacol Rearrangement and Wagner-Meerwein Rearrangement.
Can I practise Beckmann Rearrangement with quizzes?
Yes. The interactive lesson includes a self-check question on Beckmann Rearrangement, and the Organic Chemistry quiz draws on every topic in this area.
Where Beckmann Rearrangement fits in Organic Chemistry
Beckmann Rearrangement is topic 146 of 148 in Organic Chemistry.