Hinsberg reaction
[1][2] In this test, the amine is shaken well with the Hinsberg reagent (benzenesulfonyl chloride) in the presence of aqueous alkali (either KOH or NaOH).
A tertiary amine will not react with the original reagent (benzene sulfonyl chloride) and will remain insoluble.
The Hinsberg test for amines is valid only when reaction speed, concentration, temperature, and solubility are taken into account.
The sulfonamides resulting from primary and secondary amines are poorly soluble and precipitate as solids from solution.
Tertiary amines promote hydrolysis of the sulfonyl chloride functional group, which affords water-soluble sulfonate salts.
![PhSO2Cl + 2 RR'NH → PhSO2NRR' + [RR'NH2+]Cl−](http://upload.wikimedia.org/wikipedia/commons/thumb/f/f0/Hinsberg_reaction%2C_primary_amine.png/880px-Hinsberg_reaction%2C_primary_amine.png)
![PhSO2N(H)R + NaOH → Na+[PhSO2NR−] + H2O](http://upload.wikimedia.org/wikipedia/commons/thumb/0/04/Hinsberg_reaction%2C_secondary_amine.png/880px-Hinsberg_reaction%2C_secondary_amine.png)
![PhSO2Cl + R3N + H2O → R3NH+[PhSO− 3] + HCl](http://upload.wikimedia.org/wikipedia/commons/thumb/f/f9/Hinsberg_reaction%2C_tertiary_amine.png/880px-Hinsberg_reaction%2C_tertiary_amine.png)