Chloroform

Chloroform (CHCl3) is a derivative of the simplest hydrocarbon, methane. Its IUPAC name is trichloromethane. In the laboratory, it is prepared from ethanol or propanone.

Preparation of Chloroform

Chlorofom is prepared in the laboratory by treating ethanol or propanone with chlorine gas in the presence of an alkali.

Properties of Chloroform

Chlorofom is a colourless sweet smelling liquid (b.p. 334K). It is slowly oxidized by air in the presence of light to a poisonous gas, phosgene. Chemically phosgene is carbonyl chloride, (COCl2). Therefore, chloroform is stored in dark coloured bottles to protect it from light. The bottle are completely filled so that the air is kept out. A small amount of ethanol is added to chloroform to convert toxic phosgene, if formed, into a nontoxic compound, ethyl carbonate.

Uses of Chloroform

Chloroform is used in isocyanide test for the detection of primary amines. In this test, a mixture of amine and chloroform is heated with alcoholic NaOH. A foul smelling isocyanide is obtained. This test is also known as carbylamine test. It can be used to test aliphatic and aromatic primary amines.