Question

Which of the following methods is the most convenient method to prepare an amine containing one carbon atom less than the parent compound?

• A. Reduction of Isonitriles
• B. Hofmann bromamide reaction
• C. Gabriel phthalimide synthesis
• D. Reductive amination of aldehydes.

Hint:

Recall the degradation reaction of a primary amide with bromine and alkali.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
The Hofmann bromamide degradation heats a primary amide with \(\text{Br}_{2}\) and NaOH: \(\text{RCONH}_{2}+\text{Br}_{2}+4\text{NaOH}\rightarrow\text{RNH}_{2}+2\text{NaBr}+\text{Na}_{2}\text{CO}_{3}+2\text{H}_{2}\text{O}\).

Step 2: Carbon count
The carbonyl carbon is lost as carbonate, so the amine has one carbon fewer than the amide. For example, acetamide gives methylamine.

Step 3: Why the other options fail
Reduction of isocyanides, Gabriel phthalimide synthesis and reductive amination of aldehydes all keep the carbon count unchanged.

Final Answer:
The Hofmann bromamide reaction gives an amine with one carbon atom less. \[ \boxed{\text{(B) }\text{Hofmann bromamide reaction}} \]