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NEET 2017 · ChemistryHofmann degradationPrevious Year Question

Which of the following reactions is appropriate for converting acetamide to methanamine ?

Answer: (B) (B) Hoffmann hypobromamide (bromamide) reaction. \textbf{Answer:} (B) Hoffmann bromamide degradation converts an amide to a primary amine with ONE fewer carbon atom.

  1. A.(A) Carbylamine reaction
  2. B.(B) Hoffmann hypobromamide (bromamide) reaction✓
  3. C.(C) Stephen's reaction
  4. D.(D) Gabriel's phthalimide synthesis

Correct Answer

(B) (B) Hoffmann hypobromamide (bromamide) reaction

Solution & Explanation

\textbf{Answer:} (B) Hoffmann bromamide degradation converts an amide to a primary amine with ONE fewer carbon atom. \textbf{Solution:} Acetamide has two carbons; methanamine has one carbon. The Hoffmann bromamide (hypobromite) degradation, , converts a primary amide to a primary amine with the loss of one carbon (as carbonate via an isocyanate intermediate, effectively loss of ). This carbon-count change exactly matches . The carbylamine reaction (A) is a TEST for primary amines, not a preparation. Stephen's reaction (C) reduces nitriles to aldehydes. Gabriel synthesis (D) makes amines from alkyl halides, not from amides. Hence (B).

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