Ethylamine and aniline:
By Azo dye test: It involves the reaction of any aromatic primary amine with HNO2 (NaNO2 + dil. HCl) at 273-278 K followed by treatment with an alkaline solution of 2-naphthol when a brilliant yellowy orange or red coloured dye is obtained.
Aliphatic 1° amines under these conditions give a brisk evolution of N2, gas with the formation of 1° alcohol i.e., solution remains clear.
