Hexachloroethane (perchloroethane) is an organochlorine compound with the chemical formula (CCl3)2. It is a white or colorless solid at room temperature with a camphor-like odor.[3] It has been used by the military in smoke compositions, such as base-eject smoke munitions (smoke grenades).
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| Names | |
|---|---|
| Preferred IUPAC name
Hexachloroethane | |
| Other names
Carbon hexachloride, Ethane hexachloride, Perchloroethane, Sesquichloride of carbon
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| Identifiers | |
3D model (JSmol)
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| 1740341 | |
| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.000.606 |
| EC Number |
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| 26648 | |
| KEGG | |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| C2Cl6 | |
| Molar mass | 236.74 g/mol |
| Appearance | colorless crystals[1] |
| Odor | camphor-like[1] |
| Density | 2.091 g/mL at 25 °C |
| Melting point | sublimes |
| Boiling point | 183 to 185 °C (361 to 365 °F; 456 to 458 K) |
| 0.005% (22.2 °C)[1] | |
| Vapor pressure | 0.2 mmHg (20 °C)[1] |
| -112.7·10−6 cm3/mol | |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards
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Probable carcinogen, dangerous CNS depressant |
| NFPA 704 (fire diamond) | |
| Flash point | noncombustible[1] |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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4460 mg/kg (rat, oral) 4970 mg/kg (guinea pig, oral) |
| NIOSH (US health exposure limits): | |
PEL (Permissible)
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TWA 1 ppm (10 mg/m3) [skin][1] |
REL (Recommended)
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Ca TWA 1 ppm (10 mg/m3) [skin][1] |
IDLH (Immediate danger)
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Ca [300 ppm][1] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Hexachloroethane was discovered along with carbon tetrachloride by Michael Faraday in 1820. Faraday obtained it by chlorinating ethylene.[4]
Manufacture
editChlorination of tetrachloroethylene at 100–140 °C with the presence of ferric chloride is the most commonly used commercial production method, however several other methods exist. A high purity form can be produced in a small scale by reacting chlorine together with barium carbide.[5]: 101 In September 1997, it was reported as no longer being produced in the United States for commercial distribution, but was produced as a by-product of industrial chlorination process.[5]: 101
Applications
editHexachloroethane has been used in the formulation of extreme pressure lubricants. It has also been used as a chain transfer agent in the emulsion polymerization of propylene–tetrafluoroethylene copolymer. Hexachloroethane has been used as an anthelmintic in veterinary medicine (under the tradename Avlothane), a rubber accelerator, a component of fungicidal and insecticidal formulations as well as a moth repellant and a plasticizer for cellulose esters.[3]
Hexachloroethane has been used in the manufacture of degassing pellets to remove hydrogen gas bubbles from molten aluminum in aluminum foundries. This use, as well as similar uses in magnesium, is being phased out in the European Union.[6]
Use as smoke agent
editSmoke grenades, called hexachloroethane smoke or HC smoke, utilize a mixture containing roughly equal parts of hexachloroethane and zinc oxide and approximately 6% granular aluminium. These smokes are toxic, which is attributed to the production of zinc chloride (ZnCl2).[7][8] According to Steinritz et al., "Due to its potential pulmonary toxicity," zinc chloride producing smoke grenades "have been discharged from the armory of most western countries (...)."[9]
Use as a riot control agent
editMost documented uses of HC smoke as a riot control agent have occurred in the United States; its purchase towards that end has occurred in Milwaukee, Denver and Portland.[10]
Federal Protective Services (FPS) and forces from the Department of Homeland Security are believed to have used HC smoke grenades against protesters during various protests in 2020.[11] At the time, journalists photographed numerous smoke canisters labeled "HC", and measured unusually high levels of zinc and chloride in the area. However, FPS communications director Rob Sperling has denied the use of HC smoke, arguing that, of the two organizations, "FPS doesn't have any items that contain HC."[12]
Toxicity
editHexachloroethane is not particularly toxic when taken orally,[13] but is considered to be quite toxic by skin adsorption. The primary effect is depression of the central nervous system.[3] The concentration that is immediately dangerous to life or health is 300 ppm and the permissible exposure limit according to the Occupational Safety and Health Administration is 1 ppm (skin).[13] It is reasonably anticipated to be a carcinogen.[14]
References
edit- ^ a b c d e f g h NIOSH Pocket Guide to Chemical Hazards. "#0316". National Institute for Occupational Safety and Health (NIOSH).
- ^ "Hexachloroethane". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
- ^ a b c Snedecor, Gayle (1999). "Hexachloroethane". In Kroschwitz, Jacqueline I. (ed.). Kirk-Othmer Concise Encyclopedia of Chemical Technology (4th ed.). New York: John Wiley & Sons, Inc. p. 428. ISBN 978-0471419617.
- ^ Faraday, Michael (1859). Experimental Researches in Chemistry and Physics. Taylor and Francis. p. 46. ISBN 978-0-85066-841-4.
- ^ a b "Hexachloroethane 101" (PDF). September 1997.
- ^ ECHA, Annex XVII to REACH – Conditions of restriction, Restrictions on the manufacture, placing on the market and use of certain dangerous substances, mixtures and articles, entry 41: hexachloroethane
- ^ "Appendix E: Smoke And Masking Agents" (PDF). Australian Department of Veteran Affairs. December 2003. p. E-3. Archived from the original (PDF) on 2014-02-13. Retrieved 2012-10-04.
- ^ National Research Council (1997). Toxicity of Military Smokes and Obscurants, volume 1. Subcommittee on Military Smokes and Obscurants. Washington, DC: National Academy Press. p. 127
- ^ Steinritz, D., Zehfuß, F., Stenger, B., Schmidt, A., Popp, T., Kehe, K., Mückter, H., Thiermann, H., Gudermann, T. (2018). Zinc chloride-induced TRPA1 activation does not contribute to toxicity in vitro. Toxicology Letters, 293, 133–139. doi:10.1016/j.toxlet.2017.09.008
- ^ "Police deployed potentially lethal chemical during Black Lives Matter protests". Salon. 2021-02-21. Retrieved 2021-06-16.
- ^ Lerner, Sharon (October 10, 2020). "Toxic Chemical Smoke Grenades Used in Portland". The Intercept. Retrieved 2021-06-16.
- ^ "Military-grade HC smoke used against Portland protesters". KOIN.com. 2020-10-20. Retrieved 2021-06-16.
- ^ a b "Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs) Hexachloroethane". NIOSH. May 1994. Retrieved 2012-10-04.
- ^ "Report on Carcinogens, Twelfth Edition, Hexachloroethane" (PDF). NIH. 2011. Retrieved 2012-10-04.