Tetrachloroethylene

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Tetrachloroethylene
Tetrachloroethylene
Tetrachloroethylene
Tetrachloroethylene
Tetrachloroethylene
Names
Preferred IUPAC name
Tetrachloroethene
Other names
Perchloroethene; perchloroethylene; perc; PCE
Identifiers
3D model (JSmol)
1304635
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.004.388 Edit this at Wikidata
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 Mild, 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)
[3]
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
0
0
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)[2]
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
Related Related organohalides
 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 ?)

Tetrachloroethylene, also known under the systematic name tetrachloroethene, or perchloroethylene, and many other names (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 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]

Production

British physicist and chemist Michael Faraday first synthesized tetrachloroethylene in 1821 by thermal decomposition of hexachloroethane.

C2Cl6 → C2Cl4 + Cl2

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. 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 and spot removers. It is also used in aerosol preparations.

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.[5][6]

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".[7]

The International Agency for Research on Cancer has classified tetrachloroethylene as a Group 2A carcinogen, which means that it is probably carcinogenic to humans.[8] Like many chlorinated hydrocarbons, tetrachloroethylene is a central nervous system depressant and can enter the body through respiratory or dermal exposure.[9] Tetrachloroethylene dissolves fats from the skin, potentially resulting in skin irritation.

Animal studies and a study of 99 twins showed there is a "lot of circumstantial evidence" that exposure to tetrachloroethylene increases the risk of developing Parkinson's disease ninefold. Larger population studies are planned.[10] Also, tetrachloroethylene has been shown to cause liver tumors in mice and kidney tumors in male rats.[11]

At temperatures over 315 °C (599 °F), such as in welding, tetrachloroethylene can be oxidized into phosgene, an extremely poisonous gas.[12][13]

The U.S. National Institute for Occupational Safety and Health has compiled extensive health and safety information for tetrachloroethylene,[14][15] including recommendations for dry cleaning establishments.[16][17][18][19]

Tetrachloroethylene exposure has been linked to pronounced acquired color vision deficiencies after chronic exposure.[20]

Testing for exposure

Tetrachloroethylene exposure can be evaluated by a breath test, analogous to breath-alcohol measurements. Because it is stored in the body's fat and slowly released into the bloodstream, 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.[21]

Remediation and degradation

In principle, tetrachloroethylene contamination can be remediated by chemical treatment or by bioremediation. Chemical treatment involves reducing metals such as iron powder. Bioremediation entails reductive dechlorination by Dehalococcoides sp. under aerobic conditions by cometabolism by Pseudomonas sp.[22] In addition to bioremediation, TCE hydrolyzes on contact with soil.[23] Products of biodegradation products include trichloroethylene, cis-1,2-dichloroethene and vinyl chloride; full degradation converts tetrachloroethylene to ethylene and chloride.

References

  1. ^ a b c d e NIOSH Pocket Guide to Chemical Hazards. "#0599". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ "Tetrachloroethylene". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  3. ^ "Compound Summary: Tetrachloroethylene". PubChem. Retrieved 9 September 2020.
  4. ^ a b 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. ^ 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.
  6. ^ "Clinical Aspects and Treatment of the More Common Intestinal Parasites of Man (TB-33)". Veterans Administration Technical Bulletin 1946 & 1947. 10: 1–14. 1948.
  7. ^ 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.
  8. ^ IARC monograph. Tetrachloroethylene, Vol. 63, p. 159. Last Updated May 20, 1997. Last retrieved June 22, 2007.
  9. ^ Control of Exposure to Perchloroethylene in Commercial Drycleaning Archived September 1, 2009, at the Wayback Machine. Hazard Controls: Publication 97-157. National Institute for Occupational Safety and Health.
  10. ^ "Industrial Solvent Linked to Increased Risk of Parkinson's Disease". Los Angeles Times. 7 February 2010. Archived from the original on 15 March 2010.
  11. ^ "Solvents: the hazardous chemicals to avoid in everyday life - Meds News". Meds News. Retrieved 22 January 2016.
  12. ^ "ATSDR - Medical Management Guidelines (MMGs): Tetrachloroethylene (PERC)".
  13. ^ "OSH Answers:4-Working Safely with Tetrachloroethylene". Government of Canada, Canadian Centre for Occupational Health and Safety. Archived from the original on 15 July 2007. Retrieved 13 October 2011.
  14. ^ "Tetrachloroethylene (perchloroethylene)". CDC / NIOSH Workplace Safety and Health Topic. 25 October 2010. Retrieved 15 July 2016.
  15. ^ "Criteria for a Recommended Standard: Occupational Exposure to Tetrachloroethylene (Perchloroethylene) (76-185)". CDC - NIOSH Publications and Products. 6 June 2014. doi:10.26616/NIOSHPUB76128. Retrieved 15 July 2016.
  16. ^ "Control of Exposure to Perchloroethylene in Commercial Drycleaning (97-154)". CDC - NIOSH Publications and Products. 6 June 2014. doi:10.26616/NIOSHPUB97154. Retrieved 15 July 2016.
  17. ^ "Control of Exposure to Perchloroethylene in Commercial Drycleaning (Substitution) (97-155)". CDC - NIOSH Publications and Products. 6 June 2014. doi:10.26616/NIOSHPUB97155. Retrieved 15 July 2016.
  18. ^ "Control of Exposure to Perchloroethylene in Commercial Drycleaning (Machine Design) (97-156)". CDC - NIOSH Publications and Products. 6 June 2014. doi:10.26616/NIOSHPUB97156. Retrieved 15 July 2016.
  19. ^ "Control of Exposure to Perchloroethylene in Commercial Drycleaning (Ventilation) (97-157)". CDC - NIOSH Publications and Products. 6 June 2014. doi:10.26616/NIOSHPUB97157. Retrieved 15 July 2016.
  20. ^ Iregren, A (December 2002). "Color Vision and Occupational Chemical Exposure: An Overview of Tests and Effects". Neurotoxicity. 23 (6): 719–33. doi:10.1016/S0161-813X(02)00088-8. PMID 12520762.
  21. ^ "SCOEL recommendations". 22 April 2011. Retrieved 22 April 2011.
  22. ^ 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.
  23. ^ 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.

Further reading

External links

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