tetrachloroethylene

French chemist Henri Victor Regnault first synthesized tetrachloroethylene in 1839 by thermal decomposition of hexachloroethane following Michael Faraday's 1820 synthesis of protochloride of carbon (carbon tetrachloride).

:{{chem2|Cl3C\sCCl3 → Cl2C\dCCl2 + Cl2}}

Faraday was previously falsely credited for the synthesis of tetrachloroethylene, which in reality, was carbon tetrachloride.{{Primary source inline|date=October 2024}} While trying to make Faraday's "protochloride of carbon", Regnault found that his compound was different from Faraday's. Victor Regnault stated "According to Faraday, the chloride of carbon boiled around {{convert|70|C|F}} to {{convert|77|C|F}} degrees Celsius but mine did not begin to boil until {{convert|120|C|F}}".V. Regnault (1839) [https://books.google.com/books?id=px0AAAAAMAAJ&pg=PA104 "Sur les chlorures de carbone CCl et CCl²"] (On the chlorides of carbon CCl and CCl²), Annales de Chimie et de Physique, vol. 70, pages 104–107. Reprinted in German as: {{cite journal |journal =Annalen der Pharmacie |volume = 30 |issue = 3 |year = 1839 |title = Ueber die Chlorverbindungen des Kohlenstoffs, C2Cl2 und CCl2 |author = V. Regnault |doi = 10.1002/jlac.18390300310 |pages =350–352|url = https://zenodo.org/record/1426937}}

Tetrachloroethylene can be made by passing chloroform vapour through a red-hot tube, the side products include hexachlorobenzene and hexachloroethane, as reported in 1886.W. Ramsay and S. Young, Jahres-Bericht über die Leistungen der chemischen Technologie, 1886, p. 628

Most tetrachloroethylene is produced by high-temperature chlorinolysis of light hydrocarbons. The method is related to Faraday's method since hexachloroethane is generated and thermally decomposes. Side products include carbon tetrachloride, hydrogen chloride, and hexachlorobutadiene.

Several other methods have been developed. When 1,2-dichloroethane is heated to 400 °C with chlorine, tetrachloroethylene is produced:

:{{chem2|ClCH2\sCH2Cl + 3 Cl2 → Cl2C\dCCl2 + 4 HCl}}

This reaction can be catalyzed by a mixture of potassium chloride and aluminium chloride or by activated carbon. Trichloroethylene is a major byproduct, which is separated by distillation.

Worldwide production was about {{convert|1|e6MT}} in 1985.{{Ullmann |last1=Rossberg |first1=M. |last2=Lendle |first2=W. |last3=Pfleiderer |first3=G. |last4=Tögel |first4=A. |last5=Dreher |first5=E.-L. |last6=Langer |first6=E. |last7=Rassaerts |first7=H. |last8=Kleinschmidt |first8=P. |last9=Strack |first9=H. |last10=Cook |first10=R. |last11=Beck |first11=U. |last12=Lipper |first12=K.-A. |last13=Torkelson |first13=T.R. |last14=Löser |first14=E. |last15=Beutel |first15=K.K. |last16=Mann |first16=T. |title=Chlorinated Hydrocarbons |doi=10.1002/14356007.a06_233.pub2}}

Although in very small amounts, tetrachloroethylene occurs naturally in volcanoes along with trichloroethylene.{{cite journal | doi = 10.1021/np50088a001 | last = Gribble |first = G. W. | title = Naturally occurring organohalogen compounds – A comprehensive survey | journal = Progress in the Chemistry of Organic Natural Products | year = 1996 | volume = 68 | pages = 1–423 | pmid = 8795309 | issue = 10}}

Tetrachloroethylene is a nonpolar solvent for organic materials. Additionally, it is volatile, relatively stable, and non-flammable. For these reasons, it became a leading solvent in dry cleaning operations worldwide beginning in the 1940s.{{Cite journal | last1 = Ceballos | first1 = Diana M. | last2 = Fellows | first2 = Katie M. | last3 = Evans | first3 = Ashley E. | last4 = Janulewicz | first4 = Patricia A. | last5 = Lee | first5 = Eun Gyung | last6 = Whittaker | first6 = Stephen G. | title = Perchloroethylene and Dry Cleaning: It's Time to Move the Industry to Safer Alternatives | journal = Frontiers in Public Health | volume = 9 | year = 2021 | doi = 10.3389/fpubh.2021.638082 | doi-access = free | pmid = 33748070 | pmc = 7973082}} The chemist Sylvia Stoesser (1901–1991) had suggested tetrachloroethylene to be used in dry cleaning as an alternative to highly flammable dry cleaning solvents such as naphtha.{{Cite book |last=Amos |first=J. Lawrence |title=A History of the Dow Chemical Physics Lab : the freedom to be creative |date=1990 |publisher=Marcel Dekker, Inc. |editor-last=Boundy |editor-first=Ray H. |location=New York and Basel |pages=71–79 |chapter=Chlorinated solvents |editor-last2=Amos |editor-first2=J. Lawrence}}

It is also used to degrease metal parts in the automotive and other metalworking industries, usually as a mixture with other chlorocarbons. It has also been used in consumer products including paint strippers, aerosol preparations, adhesives, and spot removers.

Tetrachloroethylene was once extensively used as an intermediate in the manufacture of HFC-134a and related refrigerants.

In the early 20th century, tetrachloroethene was used for the treatment of hookworm infestation.{{cite journal |last1=Young |first1=M.D. |last2=Jeffery |first2=G.M. |last3=Morehouse |first3=W.G. |last4=Freed |first4=J.E. |last5=Johnson |first5=R.S. |year=1960 |title=The Comparative Efficacy of Bephenium Hydroxynaphthoate and Tetrachloroethylene against Hookworm and other Parasites of Man |journal=American Journal of Tropical Medicine and Hygiene |volume=9 |issue=5 |pages=488–491 |doi=10.4269/ajtmh.1960.9.488 |pmid=13787477 |s2cid=19521345}}{{cite journal |author= | title=Clinical Aspects and Treatment of the More Common Intestinal Parasites of Man (TB-33) | journal=Veterans Administration Technical Bulletin 1946 & 1947 | year=1948 | volume=10 | pages=1–14 | url=https://books.google.com/books?id=uJWxEzwqRiMC}} In 1925, American veterinarian Maurice Crowther Hall (1881–1938), working on anthelmintics, demonstrated the effectiveness of tetrachloroethylene in the treatment of ancylostomiasis caused by hookworm infestation in humans and animals. Before Hall tested tetrachloroethylene on himself, in 1921 he discovered the effectiveness of carbon tetrachloride on intestinal parasites and was nominated for the Nobel Prize in Physiology or Medicine, but a few years later he found tetrachloroethylene to be more effective and safer.{{cite web |title=Maurice C. Hall |series=Special Collections |website=United States National Agricultural Library |url=https://www.nal.usda.gov/exhibits/speccoll/items/show/8197}}

Tetrachloroethylene treatment has played a vital role in eradicating hookworms in the United States and abroad.{{cn|date=September 2024}} Hall's innovation was considered a breakthrough in medicine.{{cn|date=September 2024}} It was given orally as a liquid or in capsules along with magnesium sulfate to get rid of the Necator americanus parasite in humans.{{cite book |last=Davison |first=Forrest Ramon |title=Synopsis of materia medica, toxicology, and pharmacology for students and practitioners of medicine |year=1940 |section-url=https://archive.org/details/b32804878/page/181/mode/1up |page=181 |section=Tetrachlorethylene}}

Tetrachloroethylene is a derivative of ethylene with all hydrogens replaced by chlorine. 14.49% of the molecular weight of tetrachloroethylene consists of carbon and the remaining 85.5% is chlorine. It is the most stable compound among all chlorinated derivatives of ethane and ethylene. It is resistant to hydrolysis and less corrosive than other chlorinated solvents. It does not tend to polymerise like fluorine analogue tetrafluoroethylene, {{chem2|C2F4}}.

Tetrachloroethylene may react violently with alkali or alkaline earth metals, alkalis (sodium hydroxide and potassium hydroxide), nitric acid, beryllium, barium and aluminium.{{cite book |editor1-last=Pohanish |editor1-first=Richard P. |title=Sittig's Handbook of Toxic and Hazardous Chemical Carcinogens |edition=6th |year=2012 |publisher=Elsevier |page=2520 |isbn=978-1-4377-7870-0 |section-url=https://books.google.com/books?id=RYt0Wzb60b4C&pg=PA2520 |section=Tetrachloroethylene}}

Oxidation of tetrachloroethylene by ultraviolet radiation in air produces trichloroacetyl chloride and phosgene:

:{{chem2|4 C2Cl4 + 3 O2 -> 2 CCl3COCl + 4 COCl2}}

This reaction can be halted by using amines and phenols (usually N-methylpyrrole and N-methylmorpholine) as stabilisers. But the reaction can be done intentionally to produce trichloroacetyl chloride.

Hexachloroethane is formed when tetrachloroethylene reacts with chlorine at 50–80 °C in the presence of a small amount of iron(III) chloride (0.1%) as a catalyst:Oshin LA, Промышленные хлорорганические продукты (Promyshlennyye khlororganicheskie produkty). 1978.

:{{chem2|Cl2C\dCCl2 + Cl2 → Cl3C\sCCl3}}

CFC-113 is produced by the reaction of tetrachloroethylene with chlorine and HF in the presence of antimony pentafluoride:Knunyatsya IL. Химическая энциклопедия (Khimicheskaya Entsiklopediya). 1992. {{ISBN|5-85270-039-8}}

:{{chem2|Cl2C\dCCl2 + 3 HF + Cl2 → ClF2C\sCCl2F + 3 HCl}}

Tetrachlorodinitroethane can be obtained by nitration of tetrachloroethylene with fuming nitric acid (conc. {{chem2|HNO3}} rich in nitrogen oxides) or nitrogen tetroxide:{{cite journal |last1=Argo |first1=W. L. |last2=James |first2=E. M. |last3=Donnelly |first3=J. L. |title=Tetrachlordinitroethane |journal=The Journal of Physical Chemistry |date=November 1919 |volume=23 |issue=8 |pages=578–585 |doi=10.1021/j150197a004|url=https://zenodo.org/record/1843020}}

:{{chem2|Cl2C\dCCl2 + N2O4 → NO2Cl2C\sCCl2NO2}}

The preparation of this crystalline solid compound from Tetrachloroethylene and nitrogen tetroxide was first described by Hermann Kolbe in 1869.

Tetrachloroethylene begins to thermally decompose at 400 °C, decomposition accelerates around 600 °C, and completely decomposes at 800 °C. Organic decomposition products identified were trichlorobutene, 1,3-dichloro-2-propanone, tetrachlorobutadiene, dichlorocyclopentane, dichloropentene, methyl trichloroacetate, tetrachloroacetone, tetrachloropropene, trichlorocyclopentane, trichloropentene, hexachloroethane, pentachloropropene, hexachloropropene, hexachlorobutadiene.{{cite journal |first=Akio |last=Yasuhara |title=Thermal decomposition of tetrachloroethylene |journal=Chemosphere |volume=26 |issue=8 |date=April 1993 |pages=1507–1512 |doi=10.1016/0045-6535(93)90218-T |bibcode=1993Chmsp..26.1507Y |s2cid=94961581}}

Tetrachloroethylene is considered to be a toxin. It is identified as a health hazard and environmental hazard. Exposure to tetrachloroethylene, especially over a long term, may harm the nervous system, other organs, and increase the risk of getting cancer. It may also have effects on pregnancy and the fetus.

Reports of human injury are uncommon despite its wide usage in dry cleaning and degreasing.{{Ullmann |first1=E.-L. |last1=Dreher |first2=T. R. |last2=Torkelson |first3=K. K. |last3=Beutel |title=Chlorethanes and Chloroethylenes; In: Ullmann's Encyclopedia of Industrial Chemistry |doi=10.1002/14356007.o06_o01|date=19 November 2014|publisher=Wiley|location=Verlag|isbn=9783527306732}} Although limited by its low volatility, tetrachloroethylene has potent anaesthetic effects upon inhalation.{{cite journal |first1=Ellen B. |last1=Foot |first2=Virginia |last2=Apgar |author-link2=Virginia Apgar |first3=Kingsley |last3=Bishop |title=Tetrachlorethylene as an Anesthetic Agent |journal=Anesthesiology |date=May 1943 |volume=4 |issue=3 |pages=283–292 |s2cid=70969652 |doi=10.1097/00000542-194305000-00009 |doi-access=free}} The risk depends on whether exposure is over minutes or hours, or over years.

Despite the advantages of tetrachloroethylene, cancer research and government environmental agencies have called for its replacement from widespread commercial use. It is described as a possible neurotoxicant, liver and kidney toxicant and reproductive and developmental toxicant (...) a potential occupational carcinogen.{{cite journal |doi=10.3389/fpubh.2021.638082 |doi-access=free |title=Perchloroethylene and Dry Cleaning: It's Time to Move the Industry to Safer Alternatives |year=2021 |last1=Ceballos |first1=Diana M. |last2=Fellows |first2=Katie M. |last3=Evans |first3=Ashley E. |last4=Janulewicz |first4=Patricia A. |last5=Lee |first5=Eun Gyung |last6=Whittaker |first6=Stephen G. |journal=Frontiers in Public Health |volume=9 |page=638082 |pmid=33748070 |pmc=7973082 |s2cid=232116380}} On the other hand, dry cleaning industry emphasizes minimal risk because modern machinery use closed systems to avoid any vapour escape and to optimize recycling.

Tetrachloroethylene's biological half-life is approximately 3 days. About 98% of the inhaled tetrachloroethylene is exhaled unchanged and only about 1–3% is metabolised to tetrachloroethylene oxide which rapidly isomerises into trichloroacetyl chloride. Trichloroacetyl chloride hydrolyses to trichloroacetic acid.Toxicological Profile for Tetrachloroethylene: Draft. (1995). U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry.{{cite book |title=Biological Monitoring: An Introduction |year=1993 |editor=Shane S. Que Hee |page=470 |chapter=Biological Exposure Indices |isbn=978-0-471-29083-4 |publisher=John Wiley & Sons}}

Tetrachloroethylene can harm the nervous system, cause developmental deficits in children, impair vision, and increase the risk of psychiatric diagnoses.{{cite journal |vauthors=Grandjean P, Landrigan PJ |title=Neurobehavioural effects of developmental toxicity |journal=The Lancet. Neurology |volume=13 |issue=3 |pages=330–8 |date=March 2014 |pmid=24556010 |pmc=4418502 |doi=10.1016/S1474-4422(13)70278-3}}{{cite journal |vauthors=Aschengrau A, Janulewicz PA, White RF, Vieira VM, Gallagher LG, Getz KD, Webster TF, Ozonoff DM|display-authors=3 |title=Long-term Neurotoxic Effects of Early-life Exposure to Tetrachloroethylene-contaminated Drinking Water |journal=Annals of Global Health |volume=82 |issue=1 |pages=169–79 |date=2016 |pmid=27325074 |pmc=4916338 |doi=10.1016/j.aogh.2016.01.013}}

Tetrachloroethylene has been classified as "Group 2A: Probably Carcinogenic" by the International Agency for Research on Cancer (IARC) due to sufficient evidence in experimental animals and limited evidence in humans for non-Hodgkin lymphoma, urinary bladder cancers, and cancers of the esophagus and cervix.{{Cite web |url=https://publications.iarc.fr/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Trichloroethylene-Tetrachloroethylene-And-Some-Other-Chlorinated-Agents-2014 |title=Trichloroethylene, Tetrachloroethylene, and Some Other Chlorinated Agents (IARC Monograph, Volume 106, 2014) |website=publications.iarc.fr/ |access-date=23 September 2024}}{{rp|32}}

Although tetrachloroethylene is suspected to be a human carcinogen, there is no convincing evidence to support this. According to IARC, there is no evidence that tetrachloroethylene is responsible for the cancer cases in dry cleaners, as most of the dry cleaners with cancer diagnoses were smokers and drinkers, and many other chemicals besides tetrachloroethylene are used in dry cleaning. Tetrachloroethylene is known not to cause tumour formation in humans.Golan, D. E.; Armstrong, E. J.; Armstrong, A. W. (2017). Principles of Pharmacology: The Pathophysiology Basis of Drug Therapy. p. 916. It also does not trigger uncontrolled DNA synthesis in animal cells, which plays a major role in cancer formation.Costa, A. K.; Ivanevitch, K. M. (1984). "Chlorinated Ethylenes". Carcinogenesis. 12 (1629).

A study published in 1999, which examined cancer cases among aircraft workers in the United States over a 36-year period, found no difference in cancer rates among those who worked with tetrachloroethylene compared to those who had not used tetrachloroethylene. No significant increase was found in the incidence of suspected lymphoma, leukemia, or liver cancer.Boice, J. D.; Marano, D. E.; Fryzek, J. P. (1999). "Mortality among aircraft manufacturing workers". Occup. Environ. Med. 56: 581-597

A study published in Sweden in 2011, which investigated cancer rates among dry cleaners exposed to tetrachloroethylene for many years and laundry workers who did wet cleaning without using this chemical, based on a total of more than nine thousand people, found that there was no difference in the probability of cancer between the two groups: there was no significant increase in the incidence of esophageal, cervical, liver, kidney and bladder cancers, which are suspected to be caused by tetrachloroethylene, between the two groups.Seldén, AI; Ahlborg, G (2011). "Cancer morbidity in Swedish dry-cleaners and laundry workers: historically prospective cohort study". Int Arch Occup Environ Health. 84 (4).

Tetrachloroethylene exposure can be evaluated by a breath test, analogous to breath-alcohol measurements. Also, for acute exposures, tetrachloroethylene in expired air can be measured.{{Cite web |date=2021-02-09 |title=Tetrachloroethylene Toxicity: Section 3.1. Evaluation and Diagnosis |url=https://www.atsdr.cdc.gov/csem/tetrachloroethylene/section_3_1.html |access-date=2023-03-02 |website=Agency for Toxic Substances and Disease Registry |language=en-us}} Tetrachloroethylene can be detected in the breath for weeks following a heavy exposure. Tetrachloroethylene and its metabolite trichloroacetic acid, can be detected in the blood.

In the European Union, the Scientific Committee on Occupational Exposure Limits (SCOEL) recommends for tetrachloroethylene an occupational exposure limit (8-hour time-weighted average) of 20 ppm and a short-term exposure limit (15 min) of 40 ppm.{{cite web|url= http://ec.europa.eu/social/keyDocuments.jsp?type=0&policyArea=82&subCategory=153&country=0&year=0&advSearchKey=recommendation&mode=advancedSubmit&langId=en|title=SCOEL recommendations|date=2011-04-22|access-date=2011-04-22}}

In principle, tetrachloroethylene contamination can be remediated by chemical treatment. Chemical treatment involves reducing metals such as iron powder.{{cite journal |first1=Timothy J. |last1=Campbell |first2=David R. |last2=Burris |first3=A. Lynn |last3=Roberts |first4=J. Raymond |last4=Wells |title=Trichloroethylene and tetrachloroethylene reduction in a metallic iron–water-vapor batch system |date=October 2009 |journal=Environmental Toxicology and Chemistry |volume=16 |issue=4 |doi=10.1002/etc.5620160404 |pages=625–630 |s2cid=94525849}}

Bioremediation usually entails reductive dechlorination under anaerobic conditions by Dehalococcoides spp.{{cite journal |doi=10.1016/j.watres.2017.02.001 |title=Anaerobic biodegradation of (Emerging) organic contaminants in the aquatic environment |year=2017 |last1=Ghattas |first1=Ann-Kathrin |last2=Fischer |first2=Ferdinand |last3=Wick |first3=Arne |last4=Ternes |first4=Thomas A. |journal=Water Research |volume=116 |pages=268–295 |pmid=28347952 |doi-access=free |bibcode=2017WatRe.116..268G |s2cid=205698959}} Under aerobic conditions, degradation may occur via co-metabolism by Pseudomonas sp.{{cite journal |doi=10.1007/s002530100675 |last1=Ryoo |first1=D. |last2=Shim |first2=H. |last3=Arenghi |first3=F. L. G. |last4=Barbieri |first4=P. |last5=Wood |first5=T. K. |year=2001 |title=Tetrachloroethylene, Trichloroethylene, and Chlorinated Phenols Induce Toluene-o-xylene Monooxoygenase Activity in Pseudomonas stutzeri OX1 |journal = Appl Microbiol Biotechnol |volume=56 |pages=545–549 |issue = 3–4 |pmid = 11549035 | s2cid = 23770815}} Products of biological reductive dechlorination include trichloroethylene, cis-1,2-dichloroethylene, vinyl chloride, ethylene and chloride.

{{Notelist}}

{{Reflist}}

• {{cite web | publisher = Agency for Toxic Substances and Disease Registry | year = 1997 | title = Toxicological Profile for Tetrachloroethene | url = https://wwwn.cdc.gov/TSP/ToxProfiles/ToxProfiles.aspx?id=265&tid=48}}
• {{cite journal | author = Doherty, R.E. | year = 2000 | title = A History of the Production and Use of Carbon Tetrachloride, Tetrachloroethylene, Trichloroethylene and 1,1,1-Trichloroethane in the United States: Part 1 - Historical Background; Carbon Tetrachloride and Tetrachloroethylene | journal = Environmental Forensics | volume = 1 | pages = 69–81 | doi = 10.1006/enfo.2000.0010 | issue = 2 | bibcode = 2000EnvFo...1...69D | s2cid = 97680726}}

• [https://www.atsdr.cdc.gov/csem/csem.html ATSDR Case Studies in Environmental Medicine: Tetrachloroethylene Toxicity] U.S. Department of Health and Human Services
• [https://www.cdc.gov/niosh/topics/tetrachloro/ Tetrachloroethylene (Perchloroethylene)] U.S. Department of Health and Human Services
• Australian [http://www.npi.gov.au/substances/tetrachloroethylene/index.html National Pollutant Inventory (NPI)] page
• [https://web.archive.org/web/20151204211147/http://ecsa.cefic.org:80/index.php?option=com_content&view=article&id=4:per&catid=2:uncategorised&Itemid=111 Sustainable uses and Industry recommendations], European Chlorinated Solvents Association

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