JEE Challenger
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Hofmann Bromamide Reaction and Nitration of Aniline

Given below are two statements :

Statement I : Heating benzamide with bromine in an ethanolic solution of sodium hydroxide will give benzylamine.

Statement II : Nitration of aniline with HNO3/H2SO4\text{HNO}_3/\text{H}_2\text{SO}_4 at 288 K288\text{ K} produces mm-nitroaniline in higher amount than oo-nitroaniline (pH adjusted).

In the light of the above statements, choose the correct answer from the options given below :

Options

A

Both Statement I and Statement II are true

B

Both Statement I and Statement II are false

C

Statement I is true but Statement II is false

D

Statement I is false but Statement II is true

Correct

Topics & Concepts

Step-by-Step Solution

To determine the correctness of Statements I and II, let us analyze them individually:

Analysis of Statement I: When benzamide (C6H5CONH2\text{C}_6\text{H}_5\text{CONH}_2) is treated with bromine in the presence of an aqueous or ethanolic solution of sodium hydroxide (NaOH\text{NaOH}), it undergoes the Hofmann bromamide degradation reaction. In this reaction, the carbonyl group is removed as carbonate, yielding a primary amine containing one carbon atom fewer than the starting amide:

C6H5CONH2+Br2+4NaOHΔC6H5NH2+Na2CO3+2NaBr+2H2O\text{C}_6\text{H}_5\text{CONH}_2 + \text{Br}_2 + 4\text{NaOH} \xrightarrow{\Delta} \text{C}_6\text{H}_5\text{NH}_2 + \text{Na}_2\text{CO}_3 + 2\text{NaBr} + 2\text{H}_2\text{O}

The primary product formed is aniline (C6H5NH2\text{C}_6\text{H}_5\text{NH}_2), and not benzylamine (C6H5CH2NH2\text{C}_6\text{H}_5\text{CH}_2\text{NH}_2). Therefore, Statement I is false.


Analysis of Statement II: Direct nitration of aniline using a mixture of concentrated HNO3\text{HNO}_3 and H2SO4\text{H}_2\text{SO}_4 at 288 K288\text{ K} leads to protonation of aniline in the strongly acidic medium, forming the anilinium ion (C6H5NH3+\text{C}_6\text{H}_5\text{NH}_3^+).

Since the anilinium ion is a strong mm-directing group, a substantial amount of mm-nitroaniline is formed alongside oo- and pp- isomers. The percentage yield of the products obtained is:

  • pp-nitroaniline: 51%51\%
  • mm-nitroaniline: 47%47\%
  • oo-nitroaniline: 2%2\%

Since 47%>2%47\% > 2\%, mm-nitroaniline is formed in a significantly higher amount than oo-nitroaniline. Therefore, Statement II is true.


Conclusion:

  • Statement I is false, but Statement II is true.

Thus, the correct choice is Option D.

Hofmann Bromamide Reaction and Nitration of Aniline | Chemistry PYQ Solution - JEE Challenger