Question

The best reagent for converting propanamide into propanamine is:

• A. excess H_2
• B. Br_2 in aqueous NaOH
• C. iodine in the presence of red phosphorus
• D. LiAlH_4 in ether

Hint:

LiAlH_4 is a strong reducing agent that can reduce amides to amines.

Answer 1

The Correct Option is C

To identify the optimal reagent for transforming propanamide into propanamine, an understanding of the reduction process is necessary.

Conversion of Propanamide (CH₃CH₂CONH₂) to Propanamine (CH₃CH₂CH₂NH₂):

This transformation entails the reduction of the amide's carbonyl group (C=O) to a primary amine group (-CH₂NH₂). Various reducing agents can effect this change.

1. Excess H₂: Utilized in catalytic hydrogenation, typically with catalysts like Pd or Pt. While it reduces double bonds, it lacks selectivity for amides.
2. Br₂ in aqueous NaOH: Employed in the Hofmann Bromamide degradation, which converts primary amides to primary amines with a reduced carbon count, rendering it unsuitable for this specific reaction.
3. LiAlH₄ in ether: A potent reducing agent commonly used to reduce carboxylic acids, esters, and amides to alcohols or amines. Although effective, other reagents are more precise for this particular conversion.
4. Iodine in the presence of red phosphorus: This reagent selectively reduces amides to amines without affecting other functional groups, making it ideal for this transformation.

Considering these options, iodine in the presence of red phosphorus emerges as the superior reagent for converting propanamide to propanamine. It specifically targets and reduces the carbonyl group in amides to an amine group while preserving the integrity of the carbon chain.