Question

Hoffmann bromamide degradation reaction is shown by:
(A) $ArN{{H}_{2}}$
(B) $ArCON{{H}_{2}}$
(C) $ArN{{O}_{2}}$
(D) $ArC{{H}_{2}}N{{H}_{2}}$

Answer 1

In general, degradation reaction is a type of chemical reaction in which reactant decomposes into two or more products. Similarly, Hoffmann bromamide degradation reaction is the reaction where amide is treated with bromine to give one or more products.

Complete Solution :
Let us see what we mean by Hoffmann bromamide degradation reaction;
Hoffmann bromamide degradation-
- In this reaction, degradation of amide takes place. The amide is treated with bromine in an aqueous solution of the ethanolic solution of sodium hydroxide. This reaction results in the formation of primary amine with other products.
- Primary amines are the ones in which the amino group is directly attached to the carbon atom. This primary amine formed will contain one carbon less than the actual compound i.e. amide.
Now, let us move towards the given illustration;
- Here, we need to find the option which has amide group in it. The amide group is the one having carbonyl group linked to the nitrogen atom i.e. $ArCON{{H}_{2}}$ (from all the available options).
Benzamide is the amide group which will show the Hoffmann bromamide degradation reaction to give aniline and other products as:

$ArCON{{H}_{2}}+B{{r}_{2}}+4NaOH\to ArN{{H}_{2}}+N{{a}_{2}}C{{O}_{3}}+2NaBr+2{{H}_{2}}O$
So, the correct answer is “Option B”.

Note: This is basically the Hoffmann bromamide degradation reaction, used for the formation of primary amines. The primary amines prepared by this method are free of the contamination caused by the secondary and tertiary amines.