Tetrachloroethylene

Tetrachloroethylene
Tetrachloroethylene
Tetrachloroethylene
Tetrachloroethylene
Tetrachloroethylene
Names
Preferred IUPAC name
Tetrachloroethene
Other names
Perchloroethene; perchloroethylene; perc; PCE; carbon dichloride; carboneum dichloratum
Identifiers
3D model (JSmol)
1304635
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.004.388
EC Number
  • 204-825-9
101142
KEGG
RTECS number
  • KX3850000
UNII
UN number 1897
  • InChI=1S/C2Cl4/c3-1(4)2(5)6 checkY
    Key: CYTYCFOTNPOANT-UHFFFAOYSA-N checkY
  • InChI=1/C2Cl4/c3-1(4)2(5)6
    Key: CYTYCFOTNPOANT-UHFFFAOYAO
  • ClC(Cl)=C(Cl)Cl
Properties
C2Cl4
Molar mass 165.82 g/mol
Appearance Clear, colorless liquid
Odor Strong and sweetish, chloroform-like[1]
Density 1.622 g/cm3
Melting point −19 °C (−2 °F; 254 K)
Boiling point 121.1 °C (250.0 °F; 394.2 K)
0.15 g/L (25 °C)
Vapor pressure 14 mmHg (20 °C)[1]
−81.6·10−6 cm3/mol
Viscosity 0.89 cP at 25 °C
Hazards
GHS labelling:
GHS08: Health hazardGHS09: Environmental hazard
Warning
H351, H411
P201, P202, P273, P281, P308+P313, P391, P405, P501
NFPA 704 (fire diamond)
Flash point Not flammable
Lethal dose or concentration (LD, LC):
4000 ppm (rat, 4 hr)
5200 ppm (mouse, 4 hr)
4964 ppm (rat, 8 hr)[3]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 100 ppm
C 200 ppm (for 5 minutes in any 3-hour period), with a maximum peak of 300 ppm[1]
REL (Recommended)
 Ca Minimize workplace exposure concentrations.[1]
IDLH (Immediate danger)
 Ca [150 ppm][1]
Safety data sheet (SDS) External MSDS
Related compounds
Tetrafluoroethylene
Tetrabromoethylene
Tetraiodoethylene
Related compounds
 Trichloroethylene
Dichloroethene
Tetrachloroethane
Supplementary data page
Tetrachloroethylene (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)
Infobox references

Tetrachloroethylene, also known under the systematic name tetrachloroethene, or perchloroethylene, and abbreviations such as "perc" (or "PERC"), and "PCE", is a chlorocarbon with the formula Cl2C=CCl2. It is a colorless liquid widely used for dry cleaning of fabrics, hence it is sometimes called "dry-cleaning fluid". It also has its uses as an effective automotive brake cleaner. It has a sweet odor, similar to the smell of chloroform, detectable by most people at a concentration of 1 part per million (1 ppm). Worldwide production was about 1 million metric tons (980,000 long tons; 1,100,000 short tons) in 1985.[4]

History and production

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).

C2Cl6 → C2Cl4 + Cl2

Faraday was previously falsely credited for the synthesis of tetrachloroethylene, which in reality, was carbon tetrachloride. 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 70 °C (158 °F) to 77 °C (171 °F) degrees Celsius but mine did not begin to boil until 120 °C (248 °F) ".[5]

Tetrachloroethylene can be made by passing chloroform vapour through a red-hot tube, the side products include hexachlorobenzene and hexachloroethane, as reported in 1886.[6]

Most tetrachloroethylene is produced by high temperature chlorinolysis of light hydrocarbons. The method is related to Faraday's discovery since hexachloroethane is generated and thermally decomposes.[4] 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 by the chemical reaction:

ClCH2CH2Cl + 3 Cl2 → Cl2C=CCl2 + 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.

Uses

Tetrachloroethylene is an excellent solvent for organic materials. Otherwise it is volatile, highly stable and nonflammable, and has low toxicity. For these reasons, it is widely used in dry cleaning. It is also used to degrease metal parts in the automotive and other metalworking industries, usually as a mixture with other chlorocarbons. It appears in a few consumer products including paint strippers, aerosol preparations and spot removers.

Historical applications

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.[7][8]

Health and safety

The acute toxicity of tetrachloroethylene is moderate to low. Reports of human injury are uncommon despite its wide usage in dry cleaning and degreasing.[9]

Despite the advantages of tetrachloroethylene, many have called for its replacement from widespread commercial use. It has been described as a possible "neurotoxicant, liver and kidney toxicant, and reproductive and developmental toxicant ... a 'potential occupational carcinogen'"..[10]

Testing for exposure

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.[11] Tetrachloroethylene can be detected in the breath for weeks following a heavy exposure. Tetrachloroethylene and trichloroacetic acid (TCA), a breakdown product of tetrachloroethylene, can be detected in the blood.

In Europe, 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.[12]

Remediation and degradation

In principle, tetrachloroethylene contamination can be remediated by chemical treatment. Chemical treatment involves reducing metals such as iron powder.

In addition to bioremediation, tetrachloroethylene hydrolyzes on contact with soil.[13]

Bioremediation usually entails reductive dechlorination usually under anaerobic conditions.[14] Dehalococcoides sp. under aerobic conditions by cometabolism by Pseudomonas sp.[15] Products of biodegradation products include trichloroethylene, cis-1,2-dichloroethene and vinyl chloride; full degradation converts tetrachloroethylene into ethylene and chloride.

References
  1. NIOSH Pocket Guide to Chemical Hazards. "#0599". National Institute for Occupational Safety and Health (NIOSH).
  2. "Compound Summary: Tetrachloroethylene". PubChem. Retrieved 9 September 2020.
  3. "Tetrachloroethylene". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  4. M. Rossberg et al. "Chlorinated Hydrocarbons" in Ullmann's Encyclopedia of Industrial Chemistry, 2006, Wiley-VCH, Weinheim. doi:10.1002/14356007.a06_233.pub2
  5. V. Regnault (1839) "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: V. Regnault (1839). "Ueber die Chlorverbindungen des Kohlenstoffs, C2Cl2 und CCl2". Annalen der Pharmacie. 30 (3): 350–352. doi:10.1002/jlac.18390300310.
  6. W. Ramsay and S. Young, Jahresberichte, 1886, p. 628
  7. Young, M.D.; et al. (1960). "The Comparative Efficacy of Bephenium Hydroxynaphthoate and Tetrachloroethylene against Hookworm and other Parasites of Man". American Journal of Tropical Medicine and Hygiene. 9 (5): 488–491. doi:10.4269/ajtmh.1960.9.488. PMID 13787477.
  8. "Clinical Aspects and Treatment of the More Common Intestinal Parasites of Man (TB-33)". Veterans Administration Technical Bulletin 1946 & 1947. 10: 1–14. 1948.
  9. E.-L. Dreher; T. R. Torkelson; K. K. Beutel (2011). "Chlorethanes and Chloroethylenes". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.o06_o01. ISBN 978-3527306732.
  10. Ceballos, Diana M.; Fellows, Katie M.; Evans, Ashley E.; Janulewicz, Patricia A.; Lee, Eun Gyung; Whittaker, Stephen G. (2021). "Perchloroethylene and Dry Cleaning: It's Time to Move the Industry to Safer Alternatives". Frontiers in Public Health. 9: 638082. doi:10.3389/fpubh.2021.638082. PMC 7973082. PMID 33748070.
  11. "Tetrachloroethylene Toxicity: Section 3.1. Evaluation and Diagnosis | Environmental Medicine | ATSDR". www.atsdr.cdc.gov. 9 February 2021. Retrieved 2 March 2023.
  12. "SCOEL recommendations". 22 April 2011. Retrieved 22 April 2011.
  13. Åkesson, Sofia; Sparrenbom, Charlotte J.; Paul, Catherine J.; Jansson, Robin; Holmstrand, Henry (2021). "Characterizing natural degradation of tetrachloroethene (PCE) using a multidisciplinary approach". Ambio. 50 (5): 1074–1088. doi:10.1007/s13280-020-01418-5. PMC 8035386. PMID 33263919.
  14. Ghattas, Ann-Kathrin; Fischer, Ferdinand; Wick, Arne; Ternes, Thomas A. (2017). "Anaerobic biodegradation of (Emerging) organic contaminants in the aquatic environment". Water Research. 116: 268–295. doi:10.1016/j.watres.2017.02.001. PMID 28347952.
  15. Ryoo, D.; Shim, H.; Arenghi, F. L. G.; Barbieri, P.; Wood, T. K. (2001). "Tetrachloroethylene, Trichloroethylene, and Chlorinated Phenols Induce Toluene-o-xylene Monooxoygenase Activity in Pseudomonas Stutzeri OX1". Appl Microbiol Biotechnol. 56 (3–4): 545–549. doi:10.1007/s002530100675. PMID 11549035. S2CID 23770815.

Further reading
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