Pentachloroethane

Pentachloroethane is a chemical compound of chlorine, hydrogen, and carbon with the chemical formula C2HCl5. It is a colourless non-flammable liquid that is used as a solvent for oil and grease, in metal cleaning, and in the separation of coal from impurities.

Production and uses
Victor Regnault obtained Pentachloroethane from chlorination of various chlorinated ethanes in 1839.

Pentachloroethane can be obtained by chlorination of trichloroethylene and ethylene-catalysed chlorination of 1,2-dichloroethane. Pentachloroethane can also be obtained by the reaction of acetylene and chlorine, catalysed by aluminium chloride and antimony trichloride. It can be made as a byproduct of tetrachloroethylene production.

Pentachloroethane has limited uses as a solvent for oils and grease (especially in metal cleaning), in soil sterilisation, to remove impurities in coal and as a desiccant agent for wood. It was formerly used as a dry-cleaning solvent for a short time. It is rarely used since there are safer and more economical alternatives such as tetrachloroethylene.

It can be used as a precursor to tetrachloroethylene. Activated carbon-catalysed reaction of pentachloroethane and calcium chloride gives tetrachloroethylene by dehydrochlorination.

Safety
Although it is not flammable, pentachloroethane can oxidise to give phosgene and trichloroacetyl chloride in presence of oxygen at high temperatures. Pentachloroethane is not biodegradable and it can be toxic to aquatic life. It is toxic for humans.