JEE Challenger
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Hofmann Bromamide Reaction and Acylation Mechanism

In the reaction

Diagram 0

the structure of the Product T is

Options

A
Option A Diagram 1
B
Option B Diagram 1
C
Option C Diagram 1
Correct
D
Option D Diagram 1

Step-by-Step Solution

To determine the structure of the product T, we can analyze the reaction step-by-step:

Step 1: Hofmann Bromamide Reaction

The starting compound is 44-methylbenzamide (pp-toluamide):
H3C−C6H4−CONH2\text{H}_3\text{C}-\text{C}_6\text{H}_4-\text{CONH}_2

When treated with NaOH/Br2\text{NaOH}/\text{Br}_2 in step (1), pp-toluamide undergoes the Hofmann Bromamide Degradation. In this reaction, the carbonyl group (−C=O-\text{C}=\text{O}) of the primary amide is removed as carbonate (CO32−\text{CO}_3^{2-}), resulting in a primary amine with one less carbon atom:

H3C−C6H4−CONH2→NaOH/Br2H3C−C6H4−NH2\text{H}_3\text{C}-\text{C}_6\text{H}_4-\text{CONH}_2 \xrightarrow{\text{NaOH}/\text{Br}_2} \text{H}_3\text{C}-\text{C}_6\text{H}_4-\text{NH}_2

The product formed at the end of step (1) is pp-toluidine (44-methylaniline), where the −NH2-\text{NH}_2 group remains attached directly to the pp-tolyl ring.


Step 2: Acylation Reaction

In step (2), pp-toluidine is treated with benzoyl chloride (C6H5−CO−Cl\text{C}_6\text{H}_5-\text{CO}-\text{Cl}).

The nitrogen atom of pp-toluidine acts as a nucleophile and attacks the carbonyl carbon of benzoyl chloride in a nucleophilic acyl substitution reaction:

H3C−C6H4−NH2+C6H5−CO−Cl⟶H3C−C6H4−NH−CO−C6H5+HCl\text{H}_3\text{C}-\text{C}_6\text{H}_4-\text{NH}_2 + \text{C}_6\text{H}_5-\text{CO}-\text{Cl} \longrightarrow \text{H}_3\text{C}-\text{C}_6\text{H}_4-\text{NH}-\text{CO}-\text{C}_6\text{H}_5 + \text{HCl}

The resulting compound is NN-(pp-tolyl)benzamide, in which:

  • The −NH−-\text{NH}- group is directly linked to the pp-tolyl ring (H3C−C6H4−\text{H}_3\text{C}-\text{C}_6\text{H}_4-).
  • The carbonyl group (−C=O-\text{C}=\text{O}) is directly linked to the phenyl ring (C6H5−\text{C}_6\text{H}_5-).

This matches the structure shown in Option C.

Correct Option: C