The reagent used in the Hinsberg test of primary, secondary and tertiary amines, is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → benzenesulphonyl chloride, C6H5SO2Cl
Benzenesulphonyl chloride is Hinsberg’s reagent.
1° amine → sulphonamide with an acidic N–H, soluble in alkali.
2° amine → sulphonamide with no H on N, insoluble in alkali.
3° amine → no reaction (no H on N).
The reactions with ethylamine and diethylamine show the difference:
\( \ce{C6H5SO2Cl + H2N-C2H5 -> C6H5SO2NH-C2H5 + HCl} \) (soluble in alkali)
\( \ce{C6H5SO2Cl + HN(C2H5)2 -> C6H5SO2N(C2H5)2 + HCl} \) (insoluble in alkali)
NCERT (2026-27 edition):
Reaction with Arylsulphonyl Chloride
