Tests to distinguish 1°, 2° and 3° amines1°, 2° और 3° ऐमीनों में विभेद के परीक्षणTests to distinguish 1°, 2° and 3° amines

Class 12 Chemistry · Chapter 9 · interactive diagram

Parts and what they mean

• Carbylamine (isocyanide) test (कार्बिलऐमीन (आइसोसायनाइड) परीक्षण) — Heat the amine with chloroform and ethanolic KOH: R–NH₂ + CHCl₃ + 3KOH → R–NC + 3KCl + 3H₂O. Only primary amines (aliphatic and aromatic) respond.
• 1°: isocyanide (carbylamine) — foul smell (1°: आइसोसायनाइड (कार्बिलऐमीन) — दुर्गंध) — The offensive smell of the isocyanide confirms a primary amine.
• 2°: no carbylamine reaction (2°: कार्बिलऐमीन अभिक्रिया नहीं) — Secondary amines do not show this reaction.
• 3°: no carbylamine reaction (3°: कार्बिलऐमीन अभिक्रिया नहीं) — Tertiary amines do not show this reaction.
• Hinsberg's test (benzenesulphonyl chloride) (हिन्सबर्ग परीक्षण (बेन्ज़ीनसल्फ़ोनिल क्लोराइड)) — C₆H₅SO₂Cl (Hinsberg's reagent) reacts with 1° and 2° amines to form sulphonamides; nowadays p-toluenesulphonyl chloride is used.
• 1°: N-alkylbenzenesulphonamide, soluble in alkali (1°: N-ऐल्किलबेन्ज़ीनसल्फ़ोनैमाइड, क्षार में विलेय) — Its N–H is strongly acidic (strongly electron-withdrawing sulphonyl group), so it dissolves in KOH/NaOH.
• 2°: N,N-dialkylbenzenesulphonamide, insoluble in alkali (2°: N,N-डाइऐल्किलबेन्ज़ीनसल्फ़ोनैमाइड, क्षार में अविलेय) — No H on N → not acidic → does not dissolve in alkali.
• 3°: no reaction with benzenesulphonyl chloride (3°: बेन्ज़ीनसल्फ़ोनिल क्लोराइड से अभिक्रिया नहीं) — Tertiary amines do not react (no H on N).
• Reaction with nitrous acid (नाइट्रस अम्ल से अभिक्रिया) — HNO₂ is prepared in situ from NaNO₂ and a mineral acid (HCl). The three classes react differently.
• 1°: aliphatic → N₂ gas + alcohol; aromatic (273–278 K) → diazonium salt (1°: ऐलिफ़ैटिक → N₂ गैस + ऐल्कोहॉल; ऐरोमैटिक (273–278 K) → डाइऐज़ोनियम लवण) — Aliphatic diazonium salts are unstable and liberate N₂ quantitatively (used to estimate amino acids and proteins). Aromatic amines give stable-for-a-while arenediazonium salts in the cold.
• 2°: reacts in a different manner (2°: भिन्न प्रकार से अभिक्रिया) — NCERT only says secondary amines react with nitrous acid in a different manner — no nitrogen gas is evolved as with 1° aliphatic amines.
• 3°: reacts in a different manner (3°: भिन्न प्रकार से अभिक्रिया) — Tertiary amines also react differently from primary amines (NCERT does not go further).

Original diagram drawn by Simple Learning Hub, based on the NCERT textbook. Report a mistake