Advanced Topic 819 of 1102 Organic Chemistry
Hofmann Degradation
Converts an amide into a primary amine with one fewer carbon.
In-depth explanation of Hofmann Degradation
The Hofmann degradation converts a primary amide into a primary amine with one fewer carbon atom. Treatment with bromine and aqueous sodium hydroxide converts the amide into an N-bromoamide, which rearranges with loss of bromide through an isocyanate intermediate in which the migrating group moves from carbon to nitrogen. Hydrolysis of the isocyanate and loss of carbon dioxide then give the amine. The reaction is useful for shortening a carbon chain by exactly one carbon atom.
Going deeper: Hofmann Degradation
Key ideas: A primary amide plus Br2 and NaOH gives a primary amine with one fewer carbon (RCONH2 to RNH2), via N-bromoamide, isocyanate and loss of CO2. Configuration at the migrating group is retained. It is a way of shortening a chain while converting an acid derivative to an amine. Do not confuse it with Hofmann elimination of quaternary ammonium hydroxide, which gives the least substituted alkene.
Common mistakes and connections: Students count the product carbons wrongly or lose track of the CO2 loss. Another error is mixing the Hofmann bromamide reaction with the carbylamine reaction or Gabriel synthesis. Links to the Beckmann and other rearrangements, amine preparation and chain-length changes.
Visualization of Hofmann Degradation
A primary amide loses its carbonyl carbon as CO2 to give a primary amine with one fewer carbon, through an isocyanate; the product is an ammonia derivative. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Acetamide, CH3CONH2, is converted by the Hofmann degradation into methylamine, CH3NH2.
Frequently asked questions about Hofmann Degradation
What is Hofmann Degradation?
Converts an amide into a primary amine with one fewer carbon.
Is Hofmann Degradation a beginner, intermediate or advanced topic?
Hofmann Degradation 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 Hofmann Degradation?
Study these earlier topics in Organic Chemistry first: Amines, Basicity of Amines, Diazonium Salts.
What comes after Hofmann Degradation?
The next topics in Organic Chemistry are Nitro Compounds and Nitriles.
Can I practise Hofmann Degradation with quizzes?
Yes. The interactive lesson includes a self-check question on Hofmann Degradation, and the Organic Chemistry quiz draws on every topic in this area.
Where Hofmann Degradation fits in Organic Chemistry
Hofmann Degradation is topic 91 of 148 in Organic Chemistry.