All chemical test Tests for Amines

All chemical test Tests for Amines

Jul 25, 2022, 16:45 IST

Theoretical Explanation of Tests for Amines

Tests for Amines

Test for primary amine

(i) Carbylamine test: Heat the organic compound with alcoholic KOH and chloroform in a test-tube. A highly offensive smell is evolved due to the formation of isocyanides.

RNH2 + CHCl3 + 3KOH R-N     C + 3KCl + 3H2O

This test is applicable for aliphatic and aromatic primary amines but not for 2° and 3° amines.

(ii) Dye test: This test is applicable only for aromatic primary amines. Dissolve a small amount of the organic compound in dilute HCl. Cool it in ice-cold water bath. Add cold solution of sodium nitrite with constant stirring and then alkaline b-naphthol solution. An orange-red dye is obtained.

Tests for Secondary Amines (-NH-)

Liebermann’s nitroso test:

Dissolve some organic compound concentrated HCl and then add small amount of water. Cool the solution in ice-cold water bath and then add cold dilute NaNO2 solution.

A yellow oily emulsion is produced. Take above emulsion in a test tube and add phenol and concentrated H2SO4 to it. A green colour appears. Addition of water changes green colour to red, which changes to deep blue on adding NaOH solution.

Tests for Nitro Group

(i) Reduction test:

Find below all chemical test for amines