Question

Aniline and methylamine can be differentiated by
(A) Reaction with chloroform and aqueous solution of KOH
(B) Diazotization followed by coupling with phenol
(C) Reaction with $HN{{O}_{2}}$
(D) None of these

Answer 1

Hint: Both the aniline and methyl amine contain an amino group. The difference is that aniline is an aromatic amine, whereas methylamine is an aliphatic amine. To differentiate these compounds, one of the compounds should give a reaction which the others do not.

Complete Step by Step Solution:
The aniline and methyl amine can be differentiated by the diazotization reaction followed by coupling with phenol. The diazotization reaction is the reaction in which an aromatic amine gets converted into its diazonium salt. Also, the coupling reaction is the reaction in which arene diazonium salt reacts with highly reactive aromatic compounds containing electron-donating groups like$OH$, $N{{H}_{2}}$etc. The diazonium salt of aniline, known as benzene diazonium chloride, is prepared by the reaction of aniline with sodium nitrite $(NaN{{O}_{2}})$ in the presence of an excess of mineral acid. This benzene diazonium chloride will then undergo a coupling reaction at a low temperature (273K-278K) with phenol to form hydroxyazobenzene.


whereas methyl amine does not react with phenols.
Correct Option: (B) Diazotization followed by coupling with phenol.

Additional Information: The benzene diazonium chloride can also react with 2-naphthol to form 2-naphthol aniline dye, which is bright orange in colour. The diazonium salts can be used in the synthesis of various organic compounds. These salts also have applications in nanotechnology and in the dye and pigment industries.

Note: The Benzene diazonium chloride can also react with aniline in the presence of dilute alkali like $NaOH$ in acidic medium to form p-aminoazobenzene, which is also known as yellow dye.