Aniline differentiation

1° Amine

Primary amines that react with nitrous acid to produce nitrogen gas, indicating the presence of the amine.

Chemical Reaction for 1° Amine

CH3-NH2 + HNO2 → CH3-OH + N2 (g) + H2O, with nitrogen gas (N2) indicating a primary amine.

2° Amine

Secondary amines that react with nitrous acid to form nitraso amine, indicated by a yellow precipitate.

Chemical Reaction for 2° Amine

(CH3)2-NH2 + HNO2 → H2O + (CH3)-N-N=O, resulting in a yellow precipitate (nitraso amine).

3° Amine

Tertiary amines that react with nitrous acid to form a quaternary ammonium salt, which is soluble and colorless.

Chemical Reaction for 3° Amine

(CH3)-N + HNO2 → [(CH3)3NH]NO2, indicating the formation of a quaternary ammonium salt.