|Jmol-3D images||Image 1|
|Molar mass||84.93 g/mol|
|Density||1.33 g/cm3, liquid|
-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|
|S-phrases||S23 S24/25 S36/37|
|Main hazards||Harmful (Xn), Carc. Cat. 2B|
|Supplementary data page|
|n, εr, etc.|
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.
DCM 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
DCM'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 in a heat engine that can extract mechanical energy from small temperature differences. An example of a DCM heat engine is the drinking bird. The toy works at room temperature.
DCM 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."
DCM is used in 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.
DCM is the least toxic of the simple chlorohydrocarbons, but it is not without health risks, as its high volatility makes it an acute inhalation hazard. DCM 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 DCM 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. DCM 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 February 2013, the U.S. Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health warned that at least 14 bathtub refinishers have died since 2000 from DCM exposure. These workers had been working alone, in poorly ventilated bathrooms, with inadequate or no respiratory protection, and no training about the hazards of methylene chloride. The Massachusetts Department of Public Health posted a similar warning in April 2012.
OSHA has a methylene chloride standard.
In many countries, products containing DCM must carry labels warning of its health risks.
In Europe, the Scientific Committee on Occupational Exposure Limits (SCOEL) recommends for DCM an occupational exposure limit (8h time-weighted average) of 100 ppm and a short-term exposure limit (15 min) of 200 ppm.
- M. Rossberg et al. "Chlorinated Hydrocarbons" in Ullmann's Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim. doi:10.1002/14356007.a06_233.pub2
- V. Regnault (1839) "De l'action du chlore sur les éthers hydrochloriques de l'alcool et de l'esprit de bois, et de plusieurs points de la théorie des éthers" (On the action of chlorine on the hydrochloric ethers of ethanol and methanol, and on several points of the theory of ethers), Annales de chimie et physique, series 2, 71 : 353-431; see especially: "Seconde partie. De l'action du chlore sur l'éther hydrochlorique de l'esprit de bois" (Second part. On the action of chlorine on the hydrochloric ether of methanol [i.e., chloromethane]), pages 377-380. Regnault gives dichloromethane the name éther hydrochlorique monochloruré (monochlorinated hydrochloric ether). Note: Regnault gives the empirical formula for dichloromethane as C2H4Cl4 because during that era, chemists used incorrect atomic masses.
Reprinted in German in:
- V. Regnault (1840) "Ueber die Einwirkung des Chlors auf den Chlorwasserstoffäther des Alkohols und des Holzgeistes und über mehrere Puncte der Aethertheorie," Annalen der Chemie und Pharmacie, 33 : 310 - 334; see especially p. 328.
- V. Regnault (1840) "Ueber die Wirkung des Chlors auf den Chlorwasserstoffäther des Alkohols und des Holzgeistes, so wie über mehrere Puncte der Aethertheorie," Journal für Praktische Chemie, 19 : 193-218; see especially p. 210.
- Office of Environmental Health Hazard Assessment (September 2000). "Dichloromethane". Public Health Goals for Chemicals in Drinking Water. California Environmental Protection Agency.
- Shell Bitumen (2003-09-25). The Shell Bitumen Handbook. ISBN 978-0-7277-3220-0.
- 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.
- CDC (2012). "Fatal Exposure to Methylene Chloride Among Bathtub Refinishers — United States, 2000–2011". MMWR 61 (07): 119–122.
- 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.
- 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.
- Wells G, Waldron H (1984). "Methylene chloride burns". Br J Ind Med 41 (3): 420. PMC 1009322. PMID 6743591.
- USDHHS. "Toxicological Profile for Methylene Chloride" (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.
- OSHA QuickTakes, February 1, 2013;
- Methylene Chloride Hazards for Bathtub Refinishers
- Dangers of Bathtub Refinishing, NIOSH Science Blog, Ronald M. Hall February 4, 2013
- Bathtub Refinisher Dies From Exposure to Methylene Chloride, FACE Facts Safety Alert, Occupational Health Surveillance Program, Massachusetts Department of Public Health, April 2012
- OSHA Standard for Methylene Chloride
- "Dichloromethane to be banned in paint-strippers". 2009-01-14. Retrieved 2009-01-15.
- "COMMISSION REGULATION (EU) No 276/2010 (Official Journal of the European Union, L 86/7)". 2010-04-01. Retrieved 2012-02-07.
- "SCOEL recommendations". 2011-04-22. Retrieved 2011-04-22.
- Fatal Exposure to Methylene Chloride Among Bathtub Refinishers
- International Chemical Safety Card 0058
- NIOSH Pocket Guide to Chemical Hazards 0414
- National Pollutant Inventory - Dichloromethane Fact Sheet
- Dichloromethane at National Toxicology Program
- IARC Summaries & Evaluations Vol. 71 (1999)
- Canadian Environmental Protection Act Priority Substances List Assessment Report
- Organic Compounds Database
- Properties of Dichloromethane