How can you obtain the following from aniline? Give only chemical equations.
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Solution and Explanation
(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.
(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.
(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.
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Write IUPAC names of the following compounds and classify them into primary, secondary and tertiary amines.
(i) (CH3 )2CHNH2 (ii) CH3 (CH2 )2NH2 (iii) CH3NHCH(CH3 )2
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Give one chemical test to distinguish between the following pairs of compounds.
(i) Methylamine and dimethylamine
(ii) Secondary and tertiary amines
(iii) Ethylamine and aniline
(iv) Aniline and benzylamine
(v) Aniline and N-methylanilineAccount for the following:
(i) pKb of aniline is more than that of methylamine.
(ii) Ethylamine is soluble in water whereas aniline is not.
(iii) Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide.
(iv) Although amino group is o– and p– directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of m-nitroaniline.
(v) Aniline does not undergo Friedel-Crafts reaction.
(vi) Diazonium salts of aromatic amines are more stable than those of aliphatic amines. (vii) Gabriel phthalimide synthesis is preferred for synthesising primary amines.
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(ii) Propene is treated with \( B_2H_6 \) followed by oxidation by \( H_2O_2 / OH^- \).
(iii) Sodium t-butoxide is treated with \( CH_3Cl \). - (c) How will you convert the following:
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\includegraphics[width=0.5\linewidth]{ch32i.png} - What will be formed after oxidation of secondary alcohol with chromic anhydride (CrO3)?
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