Carbon tetrachloride, CCl4

Carbon Tetrachloride, CCl₄

Carbon tetrachloride is a colorless liquid, b.p. 77^oC. It has a sickly smell. It is insoluble in water but readily soluble in ethanol and either. Since its vapour is non-inflammable.

Preparation of carbon Tetrachloride

Carbon tetrachloride is prepared industrially in several ways:

(i)  By the action of chlorine on carbon disulphide in the presence of aluminum chloride as catalyst:

The sulphur monochloride is removed by fractional distillation, and the carbon tetrachloride is then shaken with sodium hydroxide, and finally distilled.

(ii)  By the chlorination of methane

(iii)  By chlorinolysis. This term describes the process of chlorinating an organic compound under conditions which rupture the carbon-carbon bond to yield chloro-compound with fewer carbon atoms than the original compound. Chlorinolysis may be effected with or without a catalyst, e.g., the hydrocarbon and chlorine are heated at high temperature (300-400^oC) and under high pressure (about 70 kg/cm²). The product is usually a mixture, e.g., propane gives both carbon tetrachloride and hexachloroethane:

Carbon tetrachloride is stable at red heat (about 500oC), but when its vapour comes into contract with water vapour at this temperature, some carbonyl chloride is formed:

 CCl₄   +   H₂O   →    COCl₂   +   2HCl

Hence after using pyrene to extinguish a fire, the room should be well ventilated.

Use of Carbon Tetrachloride

Carbon tetrachloride is widely used as an industrial solvent (for fats, oils, resins, lacquers, etc.). It is also used as a fire-extinguisher under the name of Pyrene. Carbon tetrachloride is reduced by moist iron filings to chloroform (q.v.). The alkaline hydrolysis of carbon tetrachloride gives the same products (formate and carbon monoxide) as chloroform, but the rate of reaction is slower.