Trichloroethylene (TCE, IUPAC name: trichloroethene) is an organochloride with the formula C2HCl3, commonly used as an industrial degreaser. It is a clear, colourless, non-flammable, volatile liquid with a sweet chloroform-like pleasant mild smell and burning sweet taste. Trichloroethylene has been sold under a variety of trade names for various purposes. Under the trade names Trimar and Trilene, it was used as a volatile anesthetic and as an inhaled obstetrical analgesic in millions of patients. Industrial abbreviations include trichlor, Trike, Tricky and tri. Trichloroethylene is heavier than water and insoluble in water, therefore it sinks under water when spilt which causes it to migrate downward through soil and aquifers. It settles at the bottom of aquifers and forms persistent subsurface contamination that is difficult to detect and remediate.
History The earliest trichloroethylene synthesis was reported by Auguste Laurent in 1836. Laurent obtained it from the action of potassium hydroxide on a mixture of 1,1,2,2-tetrachloroethane and 1,1,1,2-tetrachloroethane made from the chlorination of ethylene dichloride and notated it as C4HCl3 (at the time, the atomic weight of carbon was thought to be half of what it really is). He named trichloroethylene chlorétherise but did not investigate the compound further as his sample seemed unstable. E. Fischer obtained trichloroethylene in 1864 via the reduction of hexachloroethane with hydrogen. Fischer investigated the compound and noted its boiling point as between 87 and 90 degrees Celsius. First industrial plant for producing trichloroethylene was opened in Jajce, Austria-Hungary (modern-day Bosnia) in 1908. Commercial production of trichloroethylene began in Germany, in 1920 and in the United States in 1925. As early as 1920, trichloroethylene was reported to cause sickness and severe narcotic effects including sleepiness and fainting in exposed workers. The use of trichloroethylene in the food and pharmaceutical industries has been banned in some parts of the world since the 1970s due to concerns about its toxicity.
Anaesthesia Trichloroethylene is a good analgesic at 0.35 to 0.5% concentrations. Trichloroethylene has a blood/gas coefficient of 9, oil/gas coefficient of 714, and a minimum alveolar concentration of 0.23% in humans. It was mainly used as a general anaesthetic for small procedures and inhaled obsterical analgesic on millions of patients. Trichloroethylene was first used in the treatment of trigeminal neuralgia beginning in 1916 after the recommendation by the German neurologist Hermann Oppenheim in 1915. Trichloroethylene for use as an analgesic for neuralgia were sold under the trade names "Gemalgene", "Trethylene" and "Chlorylen" in the 1920s. American pharmacologist Dennis Emerson Jackson used trichloroethylene on patients given by the inhaler he developed in 1933 and published the report in 1934. Jackson later published a larger report on applying trichloroethylene on 300 patients along with the researchers Cecil Striker, Samuel Goldblatt, Irwin S. Warm in 1935. English anaesthetist Christopher Langton Hewer introduced trichloroethylene for anaesthetic use in Britain, in 1941. Hewer found that Imperial Chemical Industries (ICI) was already producing purified medical-grade trichloroethylene in Britain under the trade name Trilene (from trichloroethylene). Trilene was the purest TCE in the market at the time and other TCE formulations had impurities that could be unsafe for inhalation. Hewer noted that ICI sold Trilene for external wound cleaning. Hewer claimed that TCE would not pose cardiac danger based on a small group of patients, and mentions a death occurring during a TCE-nitrous oxide anaesthesia. Pioneered by ICI in Britain, its development was hailed as an anesthetic revolution. It was also sold as "Trimar" in the United States. The –mar suffix indicated study and development at the University of Maryland, e.g., "Fluoromar" for fluroxene and "Vinamar" for ethyl vinyl ether". From the 1940s through the 1980s, both in Europe and North America, trichloroethylene was used as a volatile anesthetic almost invariably administered with nitrous oxide. Marketed in the UK by Imperial Chemical Industries under the trade name Trilene it was coloured blue with a dye called waxoline blue in 1:200,000 concentration to avoid confusion with the similar-smelling chloroform. Trilene was stabilised with 0.01% thymol. "Anamenth" was an early German anaesthetic trichloroethylene formulation which contained menthol as the stabiliser. Trichloroethylene was also used as an inhaled analgesic, mainly during childbirth, often self-applied by the patient. It was introduced for obstetrical anaesthesia in 1943, and used until the 1980s. Self-administration of trichloroethylene by the patient was common for obstetrical use with specialised devices that required little supervision by the medical staff. When used in analgesic doses, it did not affect the uterine muscles during labour. Other analgesic uses included dental operations, superficial plastic and orthopedic surgeries and other small procedures that did not require muscle relaxation.
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