Test For Amines

Test for Primary Amines (Carbyl Amine Reaction):

When a primary amine is treated with a strong base in presence in chloroform, an isocyanide is formed and this isocyanide thus formed has a very foul smell.

Here attacking electrophile is the dichlorocarbene (:CCl₂). The primary amine can be identified with its foul smell.

Test for Secondary Amines (Libermann Reaction)

The secondary amine is converted into nitrosoamine by treating the amine with nitrous acid. The resultant solutions warmed with phenol and concentrated H₂SO₄, a brown or red colour is formed at first soon it changes to blue and then to green. The colour changes to red on dilution and further changes to greenish blue on treating with alkali.

Tertiary arylamines react with nitrous acid to form o-nitroso aromatic compound.