Question

Which reagent is used to distinguish between primary, secondary and tertiary amines ?

• A. C₆H₅SO₂Cl
• B. C₆H₅COCl
• C. CHCl₃ + ethanolic KOH
• D. NaOH + I₂

Hint:

Hinsberg's reagent = benzenesulphonyl chloride; gives 3 different responses for 1/2/3-amines.

Answer 1

The Correct Option is A

Decide which reagent gives three different responses. Carbylamine (CHCl₃ + ethanolic KOH) and the iodoform test (NaOH + I₂) are confirmatory tests, not a way to separate all three amine classes; benzoyl chloride acylates 1° and 2° alike.
$Hinsberg's$ reagent, benzenesulphonyl chloride, is the standard choice: 1° → alkali-soluble sulphonamide, 2° → alkali-insoluble sulphonamide, 3° → no reaction — three distinguishable results. Correct option: (A).