Hofmann Rearrangement: Mechanism, application.

Table of Contents

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.

Hofmann rearrangement

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

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.

hofmann rearrangement

Step 2: The anion reacts with bromine to form N-bromoamide.

Step 2 5

Step 3: Base abstracts remaining proton from N-bromoamide to form bromoamide which rearranges to give isocyanate intermediate.

hofmann rearrangement

Step 4: Nucleophilic addition of water to isocyanate leads to the formation of primary amine.

hofmann rearrangement

The overall mechanism can be written as:

hofmann rearrangement mechanism

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:

  1. Hofmann rearrangement can be used in the synthesis of amines
  2. This reaction can be used to decrease the carbon number in the chain.
  3. This reaction is used in the preparation of anthranilic acid from phthalimide.

Hofmann rearrangement Video:

References:

  1. Wang, Z., Comprehensive Organic Name Reactions and Reagents, John Wiley & Sons, Inc.,2010
  2. J.J. Li, Name Reactions, 4th ed.,© Springer-Verlag Berlin Heidelberg 2009
  3. Skyes, P., A Guide Book to Mechanism in Organic Chemistry, Second edition, Orient Longman Ltd., 1988
  4. March, J., Advanced Organic Chemistry, Wiley Eastern Limited, 1986.
  5. Morrison, R. T., & Boyd, R. N., Organic chemistry, Allyn and Bacon, Inc. 1987

If you want to learn more about Wagner meerwein rearrangement, then click here. Comment down if you have any problems related to this topic. Thank you.

Hofmann rearrangement

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