Hofmann rearrangement reaction, examples, mechanism, and application have been discussed here. Hofmann rearrangement reaction was first of all reported by Hofmann in 1881.
Hofmann rearrangement reaction
The reaction of primary amides with hypohalites (Br2 + NaOH) gives primary amine with one less carbon. This reaction is called the Hofmann rearrangement reaction. In this reaction, an isocyanate intermediate is formed.
It is the conversion of primary amide into primary amine with one less carbon atom via the formation of isocyanate intermediate when primary amide is treated with basic hypohalite. This reaction is also known as Hofmann bromoamide reaction, Hofmann degradation, or Hofmann reaction.
Hofmann rearrangement examples
Let’s see some examples of Hofmann rearrangement reaction.
Hofmann rearrangement mechanism
The Hofmann rearrangement reaction proceeds in the following basic steps:
Step 1: Abstraction of an acidic proton from the amino group by the base to form an anion.
Step 2: The anion reacts with bromine to form N-bromoamide.
Step 3: Base abstracts remaining proton from N-bromoamide to form bromoamide which rearranges to give isocyanate intermediate.
Step 4: Nucleophilic addition of water to isocyanate leads to the formation of primary amine.
The overall mechanism can be written as:
Hofmann rearrangement applications
Hofmann rearrangement reaction is a very important reaction in organic synthesis. Some of the major applications of this reaction are listed below:
- Hofmann rearrangement can be used in the synthesis of amines
- This reaction can be used to decrease the carbon number in the chain.
- This reaction is used in the preparation of anthranilic acid from phthalimide.
Hofmann rearrangement Video:
- Wang, Z., Comprehensive Organic Name Reactions and Reagents, John Wiley & Sons, Inc.,2010
- J.J. Li, Name Reactions, 4th ed.,© Springer-Verlag Berlin Heidelberg 2009
- Skyes, P., A Guide Book to Mechanism in Organic Chemistry, Second edition, Orient Longman Ltd., 1988
- March, J., Advanced Organic Chemistry, Wiley Eastern Limited, 1986.
- Morrison, R. T., & Boyd, R. N., Organic chemistry, Allyn and Bacon, Inc. 1987
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