We can obtain ethylamine by Hoffmann bromamide reaction. The amide used in this reaction is:a)Methanamideb)Acetamidec)Propanamided)ButanamideCorrect answer is option 'C'. Can you explain this answer?

Question

Answer

The correct answer is option C
CH₃CH₂CONH₂ (A)⟶ CH₃ − CH₂ − NH₂ (B)⟶ CH₃ − CH₂ − OH
In the above sequence A & B respectively are Br₂/KOH and HNO₂
The first step is Hoffmann bromamide degradation reaction in which an amide (propanamide) is converted to an amine (ethylamine) containing one carbon atom less. The reagent A is bromine in presence of KOH. In the second step, aliphatic primary amine (ethyl amine) reacts with nitrous acid (reagent B) to form aliphatic primary alcohol (ethyl alcohol).

Answer

When propenamide react with bromide in the presence of strong base it form isocynate which is also known as reaction intermediate .when isocynate react with water it releases CO2 gas and one less carbon primary amine which is known as ethylamine.

Answer

The correct answer is option C
CH₃CH₂CONH₂ (A)⟶ CH₃ − CH₂ − NH₂ (B)⟶ CH₃ − CH₂ − OH
In the above sequence A & B respectively are Br₂/KOH and HNO₂
The first step is Hoffmann bromamide degradation reaction in which an amide (propanamide) is converted to an amine (ethylamine) containing one carbon atom less. The reagent A is bromine in presence of KOH. In the second step, aliphatic primary amine (ethyl amine) reacts with nitrous acid (reagent B) to form aliphatic primary alcohol (ethyl alcohol).

Answer

Understanding the Hoffmann Bromamide Reaction
The Hoffmann bromamide reaction is a chemical process that converts primary amides into primary amines with the loss of one carbon atom. This transformation is crucial in organic synthesis, allowing chemists to generate amines from readily available amides.
Amide Selection for Ethylamine
In the case of ethylamine, we need to determine which amide will yield it upon undergoing the Hoffmann reaction. Ethylamine (C2H5NH2) has two carbon atoms. Therefore, the amide selected must have three carbon atoms since one carbon is lost during the reaction.
Analyzing the Options
- a) Methanamide: This amide has one carbon atom (HCONH2). It would yield methylamine (C1H5NH2) upon reaction, not ethylamine.
- b) Acetamide: Acetamide (CH3CONH2) contains two carbon atoms. It would yield ethylamine (C2H5NH2), but we need to consider the loss of one carbon.
- c) Propanamide: Propanamide (C2H5CONH2) has three carbon atoms. Upon undergoing the Hoffmann bromamide reaction, it loses one carbon atom, resulting in ethylamine (C2H5NH2). This is the correct amide for the desired product.
- d) Butanamide: Butanamide (C3H7CONH2) has four carbon atoms and would yield propylamine (C3H9NH2) after the reaction, not ethylamine.
Conclusion
The correct amide for obtaining ethylamine through the Hoffmann bromamide reaction is indeed propanamide (option 'C'), as it has the right number of carbon atoms required for this transformation.

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