Match List-I with List-II.
| List-I (Amine and reagent) | List-II (Observation) |
|---|---|
| (A) Ethanamine with benzenesulphonyl chloride | (I) No reaction takes place |
| (B) N-Ethylethanamine with benzenesulphonyl chloride | (II) The product formed is insoluble in alkali |
| (C) N,N-Diethylethanamine with benzenesulphonyl chloride | (III) Nitrogen gas is given off and an alcohol is formed |
| (D) Propan-1-amine with nitrous acid | (IV) The product formed is soluble in alkali |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A-IV, B-II, C-I, D-III
Primary, secondary and tertiary amines differ in the number of hydrogen atoms on nitrogen, and so they react differently with benzenesulphonyl chloride (Hinsberg’s reagent) and with nitrous acid.
(A) Ethanamine with benzenesulphonyl chloride — This matches (IV). The primary amine gives N-ethylbenzenesulphonyl amide. The H left on its nitrogen is strongly acidic because of the electron withdrawing sulphonyl group, so the product dissolves in alkali.
\( \displaystyle \ce{C6H5SO2Cl + H2N-C2H5 -> C6H5SO2NH-C2H5 + HCl} \)
(B) N-Ethylethanamine with benzenesulphonyl chloride — This matches (II). The secondary amine gives N,N-diethylbenzenesulphonamide, which has no H on nitrogen; it is not acidic and does not dissolve in alkali.
\( \displaystyle \ce{C6H5SO2Cl + HN(C2H5)2 -> C6H5SO2N(C2H5)2 + HCl} \)
(C) N,N-Diethylethanamine with benzenesulphonyl chloride — This matches (I). A tertiary amine has no H on nitrogen to be replaced, so it does not react.
(D) Propan-1-amine with nitrous acid — This matches (III). A primary aliphatic amine forms an unstable aliphatic diazonium salt, which gives off nitrogen and leaves propan-1-ol:
\( \displaystyle \ce{CH3CH2CH2NH2 + NaNO2 + 2HCl -> [CH3CH2CH2N2^+Cl^-] + NaCl + 2H2O} \)
\( \displaystyle \ce{[CH3CH2CH2N2^+Cl^-] + H2O -> CH3CH2CH2OH + N2 ^ + HCl} \)
NCERT (2026-27 edition):
9.6 Chemical Reactions – “(a) The reaction of benzenesulphonyl chloride with primary amine yields N-ethylbenzenesulphonyl amide.” … “The hydrogen attached to nitrogen in sulphonamide is strongly acidic due to the presence of strong electron withdrawing sulphonyl group. Hence, it is soluble in alkali.”
“Since N, N-diethylbenzene sulphonamide does not contain any hydrogen atom attached to nitrogen atom, it is not acidic and hence insoluble in alkali.”
“(c) Tertiary amines do not react with benzenesulphonyl chloride.”
“(a) Primary aliphatic amines react with nitrous acid to form aliphatic diazonium salts which being unstable, liberate nitrogen gas quantitatively and alcohols.”