Acetamide changes into methylamine by

• A. Hofmann bromamide reaction
• B. Hofmann reaction
• C. Friedel-craft’s reaction
• D. Hinsberg reaction

To determine how acetamide transforms into methylamine, we need to look at the options provided and understand the underlying chemical reactions. The correct answer is B. Hofmann reaction. Let’s break this down to understand why this is the case.

Understanding the Hofmann Reaction

The Hofmann reaction is a well-known chemical process that involves the conversion of primary amides into primary amines. In this reaction, the amide undergoes a series of steps that ultimately lead to the removal of one carbon atom, resulting in the formation of an amine. Specifically, when acetamide (which is a primary amide) is treated with bromine (Br2) in the presence of a strong base like sodium hydroxide (NaOH), it undergoes a transformation to yield methylamine.

Step-by-Step Mechanism

Here’s a simplified overview of the Hofmann reaction mechanism:

• Formation of N-haloamide: The acetamide reacts with bromine to form an N-bromoacetamide.
• Base-induced rearrangement: The strong base facilitates the rearrangement of the N-haloamide, leading to the formation of an isocyanate intermediate.
• Hydrolysis: The isocyanate then reacts with water to yield methylamine and carbon dioxide.

This sequence of reactions effectively reduces the carbon chain by one carbon atom, converting the acetamide into methylamine.

Why Other Options Are Incorrect

Let’s briefly examine why the other options do not apply:

• A. Hofmann bromamide reaction: This term is often used interchangeably with the Hofmann reaction, but it specifically refers to the initial step involving bromination. It does not encompass the entire process of converting acetamide to methylamine.
• C. Friedel-Craft’s reaction: This reaction is related to the alkylation or acylation of aromatic compounds and does not involve amides or their conversion to amines.
• D. Hinsberg reaction: This reaction is used to differentiate between primary, secondary, and tertiary amines and does not facilitate the conversion of acetamide to methylamine.

Real-World Applications

The Hofmann reaction is particularly useful in organic synthesis, especially in the pharmaceutical industry, where the production of amines is often required. Methylamine itself is a significant building block in the synthesis of various compounds, including pharmaceuticals and agrochemicals.

In summary, the transformation of acetamide to methylamine is best described by the Hofmann reaction, making option B the correct choice. Understanding these reactions not only helps in academic settings but also provides insight into practical applications in chemistry and industry.