Question

How can you obtain the following from aniline? Give only chemical equations.

Hint:

For nitration, use a mixture of concentrated HNO\textsubscript{3} and H\textsubscript{2}SO\textsubscript{4}, for chlorination, FeCl\textsubscript{3} is a good catalyst, and for oxidation, K\textsubscript{2}Cr\textsubscript{2}O\textsubscript{7} is used.

Answer 1

(a) Preparation of p-Nitroaniline

Reaction: Nitration of aniline using concentrated nitric acid and sulfuric acid.

\[ {C6H5NH2 + HNO3} \xrightarrow{{H2SO4}} {p-C6H4(NO2)NH2} \]

Explanation: Aniline reacts with nitrating mixture to give para-nitroaniline as the major product due to the activating nature of the –NH\(_2\) group.

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(b) Preparation of Chlorobenzene

Reaction: Chlorination of aniline in the presence of ferric chloride as a Lewis acid catalyst.

\[ {C6H5NH2 + Cl2} \xrightarrow{{FeCl3}} {C6H4ClNH2} \]

Explanation: Chlorine reacts with aniline to give substituted products. The reaction is usually controlled to obtain mono-chlorinated derivative such as chlorobenzene.

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(c) Preparation of Phenol

Reaction: Oxidation of aniline with potassium dichromate in acidic medium.

\[ {C6H5NH2 + K2Cr2O7 + H2SO4} \rightarrow {C6H5OH} \]

Explanation: The –NH\(_2\) group of aniline is oxidized to a hydroxyl group, yielding phenol.