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9.4.6 - Hoffmann bromamide degradation reaction

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Introduction to Hoffmann Reaction

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Teacher
Teacher

Today we will discuss the Hoffmann bromamide degradation reaction. Can anyone tell me what happens in this reaction?

Student 1
Student 1

Isn't it a way to make primary amines from amides?

Teacher
Teacher

Exactly! The reaction involves treating an amide with bromine and sodium hydroxide. What do you think happens to the structure of the amide during this process?

Student 2
Student 2

Do the carbon atoms change?

Teacher
Teacher

Yes! The primary amine we obtain has one carbon atom less than the amide. Can anyone explain how this reduction occurs?

Student 3
Student 3

I think the alkyl or aryl group migrates from the carbonyl carbon to the nitrogen during the reaction.

Teacher
Teacher

Correct! This migration is crucial for forming the primary amine. Remember this concept as it will help you understand further applications of the reaction in organic synthesis.

Teacher
Teacher

To summarize, we produce a primary amine from an amide while losing one carbon atom in the process.

Mechanism of the Reaction

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Teacher
Teacher

Now let's delve deeper into the mechanism. Who can outline the steps we take in the Hoffmann reaction?

Student 4
Student 4

First, the amide reacts with the hydroxide ion?

Teacher
Teacher

Exactly, the hydroxide ion attacks the carbonyl carbon. Once that happens, what follows?

Student 1
Student 1

Then it gets halogenated by bromine, right?

Teacher
Teacher

Correct! This forms an N-bromoamide. Who remembers what happens next?

Student 2
Student 2

I think the N-bromoamide rearranges to form the primary amine.

Teacher
Teacher

Right again! The nitrogen gains the alkyl group, resulting in the formation of a primary amine. Great job everyone!

Teacher
Teacher

To recap, we have hydroxide attacking, followed by halogenation and then rearrangement to form the primary amine.

Applications and Importance

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Teacher
Teacher

Let's talk about the applications of the Hoffmann bromamide degradation reaction. Why do you think this reaction is significant in organic chemistry?

Student 3
Student 3

It helps in making primary amines, which are important in many chemical processes?

Teacher
Teacher

That's right! Primary amines are crucial in synthesizing pharmaceuticals and agrochemicals. Can anyone think of a specific application?

Student 4
Student 4

They are used in the production of dyes and other chemical intermediates!

Teacher
Teacher

Excellent point! The ability to create primary amines from amides is a powerful tool in the chemist's toolkit. Why do you think this leads to improved efficiency in synthesis?

Student 1
Student 1

Because it allows for the conversion of complex structures into valuable products without starting from scratch?

Teacher
Teacher

Exactly! This reaction simplifies many synthetic pathways. To summarize, it plays a vital role in producing compounds needed in various industries.

Introduction & Overview

Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.

Quick Overview

The Hoffmann bromamide degradation reaction is a method for synthesizing primary amines from amides, resulting in a compound having one less carbon atom than the original amide.

Standard

This reaction involves treating an amide with bromine in a sodium hydroxide solution, which leads to the migration of an alkyl or aryl group from the carbonyl carbon of the amide to the nitrogen atom, ultimately forming a primary amine with one carbon less. This reaction highlights an important synthetic pathway in organic chemistry.

Detailed

Hoffmann Bromamide Degradation Reaction

The Hoffmann bromamide degradation reaction is a significant synthetic route in organic chemistry that allows for the preparation of primary amines. The process entails the treatment of an amide with bromine in either aqueous or ethanolic sodium hydroxide. During this reaction, an alkyl or aryl group migrates from the carbonyl carbon of the amide to the nitrogen atom, thus resulting in the formation of a primary amine that contains one less carbon atom than the original amide.

Key Points:

  • Mechanism: The hydroxide ion attacks the amide carbonyl carbon, followed by halogenation by bromine. The resulting N-bromoamide then undergoes a rearrangement to form the primary amine.
  • Important Consideration: The product formed has a direct relationship with the structure of the starting amide; therefore, careful selection of the initial amide is crucial for successful synthesis.
  • Applications: This reaction is particularly useful in organic synthesis for preparing various primary amines that are pivotal in pharmaceutical chemistry.

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Audio Book

Dive deep into the subject with an immersive audiobook experience.

Overview of the Hoffmann Bromamide Degradation Reaction

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Hoffmann developed a method for preparation of primary amines by treating an amide with bromine in an aqueous or ethanolic solution of sodium hydroxide. In this degradation reaction, migration of an alkyl or aryl group takes place from carbonyl carbon of the amide to the nitrogen atom. The amine so formed contains one carbon less than that present in the amide.

Detailed Explanation

The Hoffmann bromamide degradation reaction is a chemical process used to convert amides into primary amines. This is achieved by treating the amide with bromine and sodium hydroxide in water or ethanol. During the reaction, an alkyl or aryl group migrates from the carbonyl carbon of the amide to the nitrogen atom. This process reduces the amide by one carbon atom, resulting in the formation of a primary amine. This method is particularly useful for synthesizing primary amines with fewer carbon atoms than the original amide.

Examples & Analogies

Think of this reaction like a game of musical chairs, where the nitrogen atom takes the place of the carbon that was previously connected to the amide. Just as players rotate positions, the alkyl or aryl group shifts from one carbon to another, resulting in a new amine product. For instance, if you start with butanamide, which has four carbon atoms, the reaction will yield propylamine, containing three carbons.

Chemical Equations and Conversions

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Write chemical equations for the following conversions: (i) CH3–CH2–Cl into CH3–CH2–CH2–NH2 (ii) C6H5–CH2–Cl into C6H5–CH2–CH2–NH2

Detailed Explanation

In the first conversion, CH3-CH2-Cl (ethyl chloride) is transformed into CH3-CH2-CH2-NH2 (propylamine) using the Hoffmann bromamide degradation reaction. This is achieved by starting with an appropriate amide, then applying the reaction conditions (bromine and sodium hydroxide) to yield the corresponding amine with one fewer carbon atom. Similarly, for the second conversion, starting with C6H5-CH2-Cl (benzyl chloride), the same procedure will generate C6H5-CH2-CH2-NH2 (2-phenylethylamine). These equations underline the mechanism by which primary amines can be synthesized from alkyl halides through intermediate steps involving amides.

Examples & Analogies

Imagine you're cooking a meal that requires fewer ingredients than you have. If you have four potatoes (the amide) and need to make a dish with three potatoes (the primary amine), you can simply remove one potato. This process of reducing the ingredient to suit your recipe parallels how we can reduce carbons in a chain during chemical reactions like the Hoffmann bromamide degradation.

Identifying the Starting Amide

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Write structures and IUPAC names of the amide which gives propanamine by Hoffmann bromamide reaction.

Detailed Explanation

To determine the starting amide that yields propanamine through the Hoffmann bromamide degradation, we first recognize that propanamine has three carbon atoms. Hence, we need an amide with four carbon atoms. The structure would be butanamide (CH3-CH2-CH2-CO-NH2). Upon conducting the Hoffmann reaction on butanamide, the carbon migration leads to the formation of propanamine. This highlights how the structure of starting materials directly influences the final product of a chemical reaction.

Examples & Analogies

This is akin to a chain of events in a relay race. If the runner at the starting point is required to pass on their baton to a runner who is shorter, they must first complete their segment. The runner must ensure they're passing on the right baton (the correct amide) so that the eventual recipient (the amine) is of the desired height (the correct number of carbon atoms). Here, butanamide serves as the baton that arrives at propanamine.

Application and Utility

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The Hoffmann bromamide degradation reaction is useful in organic synthesis and provides an efficient route to primary amines from secondary amides.

Detailed Explanation

This reaction is particularly significant in organic chemistry because it allows chemists to synthesize primary amines in a straightforward manner. Primary amines can be vital in creating pharmaceuticals, dyes, and agricultural chemicals. By using the Hoffmann bromamide degradation method, it simplifies the pathway to generate compounds that can have substantial applications in various fields.

Examples & Analogies

Think of a tool in a toolbox that helps in assembling furniture. Just like that tool simplifies the process of building something useful, the Hoffmann bromamide degradation reaction provides a simplified method for generating primary amines that are constantly needed in pharmaceutical synthesis and chemical manufacturing.

Definitions & Key Concepts

Learn essential terms and foundational ideas that form the basis of the topic.

Key Concepts

  • Hoffmann Reactions: Converts amides to primary amines with one less carbon.

  • Mechanism: Involves hydroxide attack, bromination, and rearrangement.

  • Applications: Important for producing primary amines in pharmaceuticals and other industries.

Examples & Real-Life Applications

See how the concepts apply in real-world scenarios to understand their practical implications.

Examples

  • When butanamide undergoes Hoffmann degradation, it produces propanamine.

  • If benzamide is treated under the Hoffmann reaction conditions, aniline is formed.

Memory Aids

Use mnemonics, acronyms, or visual cues to help remember key information more easily.

🎵 Rhymes Time

  • Hoffmann's way, lose a C, primary amine you will see.

📖 Fascinating Stories

  • Imagine an amide on a journey in the lab. It meets bromine and sodium. They join forces, causing a carbon drop, and a new primary amine is formed.

🧠 Other Memory Gems

  • H-O-B-R-R (Hydroxide, Oxygen, Bromination, Rearrangement) reminds you of the steps in the Hoffmann reaction.

🎯 Super Acronyms

HBR - Hoffmann Bromamide Degradation Reaction.

Flash Cards

Review key concepts with flashcards.

Glossary of Terms

Review the Definitions for terms.

  • Term: Hoffmann Reaction

    Definition:

    A method that converts amides into primary amines while reducing the carbon chain length by one carbon.

  • Term: Amide

    Definition:

    An organic compound derived from ammonia by replacement of hydrogen by acyl groups.

  • Term: Bromination

    Definition:

    The addition of bromine to a compound, often to introduce a halogen atom into the molecule.

  • Term: Primary Amine

    Definition:

    An amine in which one of the hydrogens in ammonia is replaced by an alkyl or aryl group.