trichloroethylene

trichloroethylene, a colourless, toxic, volatile liquid belonging to the family of organic halogen compounds, nonflammable under ordinary conditions and used as a solvent and in adhesives. Trichloroethylene has a subtle, sweet odour.

Trichloroethylene was first prepared in 1864; its commercial manufacture, begun in Europe in 1908, is based on the reaction of 1,1,2,2-tetrachloroethane with dilute caustic alkali. The compound is denser than water, in which it is practically insoluble.

Trichloroethylene is used in dry cleaning, in degreasing of metal objects, and in extraction processes, such as removal of caffeine from coffee or of fats and waxes from cotton and wool. It is also used in adhesives, such as cement for polystyrene plastics like those found in model-building kits. Industrially, an important use for trichloroethylene is in the manufacture of tetrachloroethylene: trichloroethylene is treated with chlorine to form pentachloroethane, which is converted to tetrachloroethylene by reaction with caustic alkali or by heating in the presence of a catalyst.

Inhalation of the vapours (glue-sniffing) induces euphoria; the practice can be addictive. Inhalation of more than 50 ppm (parts per million) trichloroethylene can produce acute effects on the body, including nausea and vomiting, eye and throat irritation, dizziness, headache, and liver, heart, or neurological damage. Trichloroethylene exposure has been linked to Parkinson disease.

The manufacture, use, and disposal of trichloroethylene has led to the chemical’s presence in sources of groundwater and surface waters. Studies in animals suggest that consumption of trichloroethylene-contaminated water can cause organ damage and may lead to heart defects in developing fetuses. Hence, it is recommended that pregnant women avoid exposure.