Dichloromethane Identifiers CAS number PubChem ChemSpider UNII EC number KEGG ChEBI ChEMBL RTECS number PA8050000 Jmol-3D images Image 1 Properties Molecular formula CH2Cl2 Molar mass 84.93 g/mol Appearance Colorless liquid Density 1.33 g/cm3, liquid Melting point
-96.7 °C, 176 K, -142 °F
39.6 °C, 313 K, 103 °F
Solubility in water 13 g/L at 20 °C Vapor pressure 47 kPa at 20 °C Hazards MSDS External MSDS R-phrases S-phrases Main hazards Harmful (Xn), Carc. Cat. 2B NFPA 704 Flash point None Autoignition
556 °C Supplementary data page Structure and
n, εr, etc. Thermodynamic
Solid, liquid, gas
Spectral data UV, IR, NMR, MS (what is: /?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Dichloromethane (DCM or methylene chloride) is an organic compound with the formula CH2Cl2. This colorless, volatile liquid with a moderately sweet aroma is widely used as a solvent. Although it is not miscible with water, it is miscible with many organic solvents. It was first prepared in 1840 by the French chemist Henri Victor Regnault, who isolated it from a mixture of chloromethane and chlorine that had been exposed to sunlight.
Dichloromethane is produced by treating either methyl chloride or methane with chlorine gas at 400–500 °C. At these temperatures, both methane and methyl chloride undergo a series of reactions producing progressively more chlorinated products.
- CH4 + Cl2 → CH3Cl + HCl
- CH3Cl + Cl2 → CH2Cl2 + HCl
- CH2Cl2 + Cl2 → CHCl3 + HCl
- CHCl3 + Cl2 → CCl4 + HCl
Dichloromethane's volatility and ability to dissolve a wide range of organic compounds makes it a useful solvent for many chemical processes. Concerns about its health effects have led to a search for alternatives in many of these applications.
It is widely used as a paint stripper and a degreaser. In the food industry, it has been used to decaffeinate coffee and tea as well as to prepare extracts of hops and other flavorings. Its volatility has led to its use as an aerosol spray propellant and as a blowing agent for polyurethane foams.
The chemical compound's low boiling point allows the chemical to function as a heat engine that can extract movement from low grade temperatures. An example of a Dichloromethane heat engine is the drinking bird. The toy works at room temperature.
Dichloromethane chemically welds certain plastics; for example, it is used to seal the casing of electric meters. Often sold as a main component of plastic welding adhesives, it is also used extensively by model building hobbyists for joining plastic components together — it is commonly referred to as "Di-clo."
Dichloromethane is used within the material testing field of civil engineering; specifically it is used during the testing of bituminous materials as a solvent to separate the binder from the aggregate of an asphalt or macadam to allow the testing of the materials.
Dichloromethane is the least toxic of the simple chlorohydrocarbons, but it is not without its health risks as its high volatility makes it an acute inhalation hazard. Dichloromethane is also metabolized by the body to carbon monoxide potentially leading to carbon monoxide poisoning. Acute exposure by inhalation has resulted in optic neuropathy and hepatitis. Prolonged skin contact can result in the dichloromethane dissolving some of the fatty tissues in skin, resulting in skin irritation or chemical burns.
It may be carcinogenic, as it has been linked to cancer of the lungs, liver, and pancreas in laboratory animals. Dichloromethane crosses the placenta. Fetal toxicity in women who are exposed to it during pregnancy, however, has not been proven. In animal experiments, it was fetotoxic at doses that were maternally toxic but no teratogenic effects were seen.
In many countries, products containing dichloromethane must carry labels warning of its health risks.
In the European Union, the European Parliament voted in 2009 to ban the use of dichloromethane in paint-strippers for consumers and many professionals. The ban took effect in December 2010.
In Europe, the Scientific Committee on Occupational Exposure Limits (SCOEL) recommends for dichloromethane an occupational exposure limit (8h time-weighted average) of 100 ppm and a short-term exposure limit (15 min) of 200 ppm. 
- ^ a b c M. Rossberg et al. “Chlorinated Hydrocarbons” in Ullmann’s Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim. doi:10.1002/14356007.a06_233.pub2
- ^ Office of Environmental Health Hazard Assessment (September 2000). "Dichloromethane". Public Health Goals for Chemicals in Drinking Water. California Environmental Protection Agency. http://www.oehha.ca.gov/water/phg/pdf/dcm.pdf.
- ^ Shell Bitumen (2003-09-25). The Shell Bitumen Handbook. ISBN 9780727732200. http://books.google.com/?id=bA1tIkRJL8kC&pg=PA277&lpg=PA277&dq=aliquot+bitumen+solvent+methylene+chloride.
- ^ Rioux JP, Myers RA (1988). "Methylene chloride poisoning: a paradigmatic review". J Emerg Med 6 (3): 227–238. doi:10.1016/0736-4679(88)90330-7. PMID 3049777.
- ^ Fagin J, Bradley J, Williams D (1980). "Carbon monoxide poisoning secondary to inhaling methylene chloride". Br Med J 281 (6253): 1461. doi:10.1136/bmj.281.6253.1461. PMC 1714874. PMID 7437838. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1714874.
- ^ Kobayashi A, Ando A, Tagami N, Kitagawa M, Kawai E, Akioka M, Arai E, Nakatani T, Nakano S, Matsui Y, Matsumura M (2008). "Severe optic neuropathy caused by dichloromethane inhalation". J Ocul Pharmacol and Ther 24 (6): 607–612. doi:10.1089/jop.2007.0100. PMID 19049266.
- ^ Cordes DH, Brown WD, Quinn KM (1988). "Chemically induced hepatitis after inhaling organic solvents". West J Med 148 (4): 458–460. PMC 1026148. PMID 3388849. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1026148.
- ^ Wells G, Waldron H (1984). "Methylene chloride burns". Br J Ind Med 41 (3): 420. PMC 1009322. PMID 6743591. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1009322.
- ^ a b USDHHS. "Toxicological Profile for Methylene Chloride" (PDF). http://www.atsdr.cdc.gov/toxprofiles/tp14.pdf. Retrieved 2006-09-10.
- ^ Bell B, Franks P, Hildreth N, Melius J (1991). "Methylene chloride exposure and birthweight in Monroe County, New York". Environ Res 55 (1): 31–9. doi:10.1016/S0013-9351(05)80138-0. PMID 1855488.
- ^ "Dichloromethane to be banned in paint-strippers". 2009-01-14. http://www.europarl.europa.eu/news/expert/infopress_page/064-46096-012-01-03-911-20090113IPR46095-12-01-2009-2009-false/default_en.htm. Retrieved 2009-01-15.
- ^ "SCOEL recommendations". 2011-04-22. http://ec.europa.eu/social/keyDocuments.jsp?type=0&policyArea=82&subCategory=153&country=0&year=0&advSearchKey=recommendation&mode=advancedSubmit&langId=en. Retrieved 2011-04-22.
- International Chemical Safety Card 0058
- NIOSH Pocket Guide to Chemical Hazards 0414
- National Pollutant Inventory - Dichloromethane Fact Sheet
- MSDS at Oxford University
- Dichloromethane at National Toxicology Program
- IARC Summaries & Evaluations Vol. 71 (1999)
- Canadian Environmental Protection Act Priority Substances List Assessment Report
- Organic Compounds Database
Concepts in organic chemistry Halomethanes Monosubstituted Disubstituted Trisubstituted
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