Question

Write structure and $\text{IUPAC}$ name of:

$A)$ the amide which gives propanamine by Hoffmann bromamide reaction.

$B)$ the amine produced by the Hoffmann degradation of benzamide.

Answer 1

$A)$ Hoffmann's bromamide reaction

When an amide is treated with bromine in an aqueous or ethanolic solution of $NaOH$ or $KOH$, degradation of amide takes place leading to the formation of primary amine and is popularly known as Hoffmann bromamide degradation reaction.

The primary amine thus formed contains one carbon less than the number of carbon atoms in that amide.

Since propanamine contain three carbons in hydrocarbon chain of amine. Hence, the amide molecule must contain four carbon atoms. Synthesis reaction of propanamine is shown below:

$\text{IUPAC}$ name of the Amide

$\text{IUPAC}$ name of the starting amide with four carbon atoms are given below:



$B)$ Hoffmann's bromamide reaction

When an amide is treated with bromine in an aqueous or ethanolic solution of $NaOH$ or $KOH$, degradation of amide takes place leading to the formation of primary amine and is popularly known as Hoffmann bromamide degradation reaction.

The primary amine thus formed contains one carbon less than the number of carbon atoms in that amide.

Benzamide is an aromatic amide containing seven carbon atoms. Hence, the amine formed from benzamide is aromatic primary amine containing six carbon atoms. Therefore, aromatic primary amine containing six carbon atoms is aniline. Synthesis reaction of aniline from benzamide shown below:


$\text{IUPAC}$ name of the amine

$\text{IUPAC}$ name of the amine produced by the Hoffmann degradation of benzamide given below: