Question:

When acetamide is treated with $ Br_2 $ and caustic soda, the product formed is

Updated On: May 14, 2024
  • $ N $ -bromamide
  • bromoacetic acid
  • methenamine
  • ethanamine
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The Correct Option is C

Solution and Explanation

The correct option is(C): methenamine.

Amides react with bromine and caustic soda to give their corresponding primary amines. Thus, acetamide gives methanamine. This reaction is known as Hofmann's bromamide degradation reaction. 

\(\underset{\text{acetamide}}{H_3C-\overset{\underset{||}{O}}{C} - NH_2} + Br_2 + 4KOH \ce{->[343K]}\)
\(2 KBr + K _{2} CO _{3}+ \underset{\text{methanamine}}{H _{3} C - NH _{2}}+2 H _{2} O\)

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Concepts Used:

Preparation of Amines

  • Reduction of nitro compounds: Nitro compounds are reduced to amines by reduction with metals in an acidic medium or by passing them through hydrogen gas in the presence of finely divided nickel, palladium, or platinum.
  • Ammonolysis of alkyl halides: Alkyl benzyl halide undergoes a nucleophilic substitution reaction while reacting with an ethanolic solution of ammonia where the halogen atom is replaced by an amino group and this process of splitting of the C-X bond by an ammonia molecule is called ammonolysis.
  • Reduction of Nitriles: On reduction of nitriles with lithium or aluminum hydride or catalytic hydrogenation are used.
  • Reduction of amides: On reduction, the amides with lithium aluminum hydride yield amines.
  • Gabriel phthalimide synthesis: Gabriel synthesis is used to prepare primary amines. Phthalimidewhen treated with ethanolic potassium hydroxide, forms potassium salt of phthalimide which when heated with alkyl halide followed by alkaline hydrolysis leads to the formation of the corresponding primary amine.
  • Hoffmann bromamide degradation reaction: In the Hoffmann bromamide degradation reaction, the transfer of an alkyl or aryl group takes place from the carbonyl carbon of the amide to the nitrogen atom. The amine so formed, therefore, contains one carbon less than that present in the initial amine.