Diethylamine reacts with nitrous acid to form N-nitrosoamine which is water insoluble yellow oil while triethylamine reacts with nitrous acid to form soluble nitrite salt. There is no visible sign of reaction. Diethylamine reacts with benzene sulphonyl chloride and forms a solid insoluble in alkali. Tertiary amine (triethyl amine) does not react with benzene sulphonyl chloride.