(i) The carbylamine reaction is a test for determining the presence of primary amines. Carbylamines (or isocyanides) are produced d when aliphatic and aromatic primary amines are heated with chloroform and ethanolic potassium hydroxide. The odor of carbylamines is extremely unpleasant. This test has no effect on secondary or tertiary amines.

(ii) At low temperatures ( 273–278 K ), aromatic primary amines react with nitrous acid (produced in situ from NaNO₂ and a mineral acid such as HCl) to produce diazonium ions. Diazotization is the process of converting aromatic primary amines into diazonium ions.

Aniline, for example, yields benzene diazonium chloride when treated with NaNO₂ and HCl at 273–278 K, with NaCl and H₂O as by-products.