Hinsberg Test for Amine

Distinction between primary, secondary and tertiary amine Using Hinsberg  reagent


Three classes of amines are distinguished by Hinsberg reagent test. The Hinsberg reagent is benzene sulphonyl chloride (C₆H₅SO₂Cl).


1. Reaction of Hinsberg reagent with Primary amine

A primary amine forms a precipitate of N-alkyl benzene sulphonamide with Hinsberg reagent. This precipitate is soluble in alkali.

RNH₂ (primary amine)  +  C₆H₅SO₂Cl (Hinsberg reagent) ------------>  R-NH-SO₂-C₆H₅  ------(NaOH)---> R-N^-Na⁺-SO₂C₆H₅ (soluble)



2. Reaction of Hinsberg reagent with secondary amine

 Secondary amine reacts with Hinsberg reagent to form a precipitate N,N-dialkyl benzene sulphonamide. But this precipitate is insoluble in alkali.


R₂NH (secondary amine)  +  C₆H₅SO₂Cl (Hinsberg reagent) ------------> R₂NSO₂C₆H₅ (precipitate)  -----(NaOH)---> insoluble (no reaction)



2. Reaction of Hinsberg reagent with Tertiary amine


Tertiary amines do not react with Hinsberg reagent,


R₃N (Tertiary amine)  +  C₆H₅SO₂Cl (Hinsberg reagent) ------------>No reaction



Hinsberg reagent can also be used for the separation of primary, secondary and tertiary amine from a mixture.