Question

When acetamide is treated with \(\mathrm{Br}_{2}\) and caustic soda, then we get (a) bromoacetic acid (b) acetic acid (c) methylamine (d) ethane

Short answer

The product is methylamine (c).

Step-by-step solution

Understanding the Reaction Type

The given reaction involves the treatment of acetamide with bromine (23) and caustic soda (sodium hydroxide, NaOH). This is a typical Hofmann Bromamide Reaction, where primary amides are converted into primary amines with one carbon atom less.

Identifying the Product

In the Hofmann Bromamide Reaction, acetamide (2H3CONH2) is treated with 23 and NaOH to produce a primary amine. The reaction leads to the formation of methylamine (4NH2), where the amine formed has one less carbon atom than the original amide.

Verifying the Reaction Mechanism

The mechanism of this reaction involves the formation of an isocyanate intermediate, which is hydrolyzed to give the primary amine along with other by-products. In this case, acetamide is converted to methylamine and there is a loss of a carbon atom from the amide in the process.

Key concepts

Acetamide

Acetamide is an organic compound composed of a methyl group linked to an amide group (CH₃CONH₂). It is characterized by its unique amide bond, which is formed between a carbonyl group and an amino group, making it a primary amide. In chemistry, acetamide serves as an important starting material due to its simple structure and reactivity.

The Hofmann Bromamide Reaction is particularly notable for its application with acetamide, transforming this compound into a smaller amine through a relatively straightforward process. This transformation is valuable in synthetic chemistry, especially when downsizing carbon chains while converting the amide into amine functional groups.

• Acetamide - contains a methyl (CH₃) group linked to an amide (CONH₂).
• Used in reactions to synthesize smaller amines like methylamine.
• Conversion involves breaking the C-N bond and replacing it with a simpler amine.

Methylamine

Methylamine is a simple and important organic compound with the formula CH₃NH₂. It is classified as a primary amine, which means it contains an amino group (NH₂) attached to a single carbon atom, in this case, a methyl group.

When acetamide undergoes the Hofmann Bromamide Reaction, it is converted to methylamine, illustrating how a primary amide can be effectively reduced to a primary amine with one less carbon atom. This reaction is valuable in organic synthesis, where the transformation of larger amides into smaller amines like methylamine can simplify the molecular structure or adjust the chemical properties of the compound for further applications.

• Primary amine with the structure CH₃NH₂.
• Contains an NH₂ group bonded to a methyl group.
• Formed from acetamide in the Hofmann Bromamide Reaction.

Reaction Mechanism

The Hofmann Bromamide Reaction proceeds through a specific reaction mechanism that involves several key steps and the formation of an intermediate compound known as an isocyanate. Initially, the reaction between acetamide and bromine in a basic environment (NaOH) results in the halogenation of the nitrogen atom.

This leads to the creation of a bromamide intermediate. Through several reaction stages involving base-induced rearrangement, this bromamide transforms into an isocyanate. The isocyanate intermediate then hydrolyzes, forming the primary amine—methylamine—and releasing a molecule of carbon dioxide.

• Begins with acetamide reacting with Br₂ and NaOH.
• Forms a bromamide intermediate, then rearranges to an isocyanate.
• Isocyanate hydrolyzed to produce methylamine and CO₂.

Primary Amines

Primary amines are organic compounds that contain a basic nitrogen atom with a lone pair, bonded to a single alkyl group and two hydrogen atoms (RNH₂). They are a vital class of compounds in both industrial and biological chemistry due to their reactivity and functional versatility.

Methylamine, produced through the Hofmann Bromamide Reaction, is an example of a primary amine created from an amide. The reaction specifically reduces the carbon content of the amide, making it an effective way to synthesize simpler amines from more complex amide structures. The unique ability of primary amines to engage in further chemical reactions makes them invaluable in the synthesis of a wide range of chemical agents and pharmaceuticals.

• Contain an amino group bonded to an alkyl group and two hydrogens.
• Example: Methylamine (CH₃NH₂).
• Transformational chemistry due to nitrogen's reactivity.