Hoffmann bromamide degradation
An amide treated with bromine and aqueous or alcoholic NaOH gives a primary amine with one carbon atom fewer.
EthanamideCH₃CONH₂Amide - Step 1
Br₂ + NaOH(aq)
MethanamineCH₃NH₂Amine
How it works
- Br₂ and NaOH N-brominate the amide to give an N-bromoamide.
- Base removes N-H and the alkyl group migrates from carbon to nitrogen, forming an isocyanate.
- Hydrolysis of the isocyanate loses CO₂ to give the amine.
What it makes
Primary amines with one carbon fewer, including pure aniline from benzamide.
Where it fails
Only primary amides work. The amine is one carbon shorter.
Class 12, Chapter 9 Amines
Hoffmann bromamide degradation: quick answers
How many carbons does the amine have?
One fewer than the amide.
What is the isocyanate intermediate?
R-N=C=O, which is hydrolysed and loses CO2.
How do you convert ethanamine into methanamine?
Oxidise to ethanoic acid, convert to ethanamide with NH3 and heat, then use bromamide degradation.