View source for Dichloromethane

{{chembox
| Watchedfields = changed
| verifiedrevid = 267273333
| ImageFileL1 = Dichloromethane.svg
| ImageSizeL1 = 100px
| ImageFileR1 = Dichloromethane-3D-vdW.png
| ImageSizeR1 = 120px
| IUPACName = Dichloromethane
| OtherNames = Methylene chloride, methylene dichloride, Solmethine, Narkotil, Solaesthin, Di-clo, Freon 30, R-30, DCM, UN 1593, MDC
| Section1 = {{Chembox Identifiers
| CASNo = 75-09-2
| CASNo_Ref = {{cascite}}
| EINECS = 200-838-9
| PubChem = 6344
| SMILES = C(Cl)Cl
| InChI = 1/CH2Cl2/c2-1-3/h1H2
| RTECS = PA8050000
| ChEBI = 15767
| KEGG = C02271
 }}
| Section2 = {{Chembox Properties
| Formula = CH<sub>2</sub>Cl<sub>2</sub>
| MolarMass = 84.93 g/mol
| Appearance = Colorless liquid
| Density = 1.3266 g/cm<sup>3</sup>, liquid
| MeltingPtC = -96.7
| BoilingPtC = 40
| Solubility = 13 g/L at 20 °C
| VaporPressure = 47 kPa at 20 °C
 }}
| Section3 = {{Chembox Hazards
| MainHazards = Harmful ('''Xn'''), [[Carcinogen|Carc. Cat. 2B]]
| NFPA-H = 2
| NFPA-F = 1
| NFPA-R = 0
| NFPA-O =
| RPhrases = {{R40}}
| SPhrases = {{S23}} {{S24/25}} {{S36/37}}
| FlashPt = None
| Autoignition = 556 °C
 }}
}}

[[Image:Dichloromethane near IR spectrum.png|thumb|right|250px|[[near ir spectroscopy|Near IR absorption spectrum]] of dichloromethane showing complicated overlapping [[overtones]] of mid IR absorption features.]]

'''Dichloromethane''' (DCM or methylene chloride) is an [[organic compound]] with the [[chemical formula|formula]] [[Carbon|C]][[Hydrogen|H]]<sub>2</sub>[[Chlorine|Cl]]<sub>2</sub>. This colorless, volatile liquid with a moderately sweet aroma is widely used as a [[solvent]]. More than 500,000 tons were produced in 1991. Although it is not [[miscible]] with water, it is miscible with many organic [[solvent]]s.<ref name=Ullmann>M. Rossberg et al. “Chlorinated Hydrocarbons” in Ullmann’s Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim. {{DOI|10.1002/14356007.a06_233.pub2}}</ref> It was first prepared in 1840 by the [[France|French]] [[chemist]] [[Henri Victor Regnault]], who isolated it from a mixture of [[chloromethane]] and [[chlorine]] that had been exposed to [[sunlight]].

==Production==
Dichloromethane is produced by [[chemical reaction|treating]] either methyl chloride or methane with chlorine gas at 400&ndash;500&nbsp;°C. At these temperatures, both methane and methyl chloride undergo a series of reactions producing progressively more chlorinated products.<ref name=Ullmann/>

:[[methane|CH<sub>4</sub>]] + [[chlorine|Cl<sub>2</sub>]] → [[methyl chloride|CH<sub>3</sub>Cl]] + [[hydrogen chloride|HCl]]
:CH<sub>3</sub>Cl + Cl<sub>2</sub> → CH<sub>2</sub>Cl<sub>2</sub> + HCl
:CH<sub>2</sub>Cl<sub>2</sub> + Cl<sub>2</sub> → [[chloroform|CHCl<sub>3</sub>]] + HCl
:CHCl<sub>3</sub> + Cl<sub>2</sub> → [[carbon tetrachloride|CCl<sub>4</sub>]] + HCl
The output of these processes is a mixture of [[methyl chloride]], dichloromethane, [[chloroform]], and [[carbon tetrachloride]]. These compounds are separated by [[distillation]].

==Uses==
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.<ref name=Ullmann/>

It is widely used as a [[paint stripper]] and a [[degreaser]]. In the [[food industry]], it has been used to [[decaffeination|decaffeinate]] [[coffee]] and [[tea]] as well as to prepare extracts of [[hops]] and other [[flavoring]]s.<ref>{{cite web|author = Office of Environmental Health Hazard Assessment|publisher = [[California Environmental Protection Agency]]|month = September|year = 2000|work = Public Health Goals for Chemicals in Drinking Water|title = Dichloromethane|url = http://www.oehha.ca.gov/water/phg/pdf/dcm.pdf}}</ref> Its volatility has led to its use as an [[Aerosol_spray#Aerosol propellants|aerosol spray propellant]] and as a [[blowing agent]] for [[polyurethane]] [[foam]]s.

====Specialized uses====
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 in the model-making industry for joining plastic components together — it is commonly referred to as "Di-clo."

Also used in the garment printing industry for removal of heat-sealed garment transfers. Usually sold in cans with methanol as the propellant gas.{{Citation needed|date=August 2010}} Its volatility is exploited in novelty items — [[drinking bird]]s, [[bubble light]]s, and [[jukebox]] displays.

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.<ref>{{cite book|author = [[Royal Dutch Shell|Shell Bitumen]]|title = The Shell Bitumen Handbook|url = http://books.google.com/?id=bA1tIkRJL8kC&pg=PA277&lpg=PA277&dq=aliquot+bitumen+solvent+methylene+chloride|isbn = 9780727732200|date = 2003-09-25}}</ref>

==Toxicity==
Dichloromethane is the least [[toxic]] of the simple chlorohydrocarbons, but it is not without its health risks as its high [[Volatility (chemistry)|volatility]] makes it an acute inhalation hazard.<ref>{{cite journal|author = Rioux JP, Myers RA|title = Methylene chloride poisoning: a paradigmatic review|journal = J Emerg Med|volume = 6|issue = 3|pages = 227–238|year = 1988|pmid = 3049777|doi = 10.1016/0736-4679(88)90330-7}}</ref> Dichloromethane is also metabolised by the body to [[carbon monoxide]] potentially leading to [[carbon monoxide poisoning]].<ref>{{cite journal|author = Fagin J, Bradley J, Williams D|title = Carbon monoxide poisoning secondary to inhaling methylene chloride|journal = Br Med J|volume = 281|issue = 6253|pages = 1461|year = 1980|pmid = 7437838|doi = 10.1136/bmj.281.6253.1461|pmc = 1714874}}</ref> Acute exposure by inhalation has resulted in optic neuropathy<ref>{{cite journal|author = Kobayashi A, Ando A, Tagami N, Kitagawa M, Kawai E, Akioka M, Arai E, Nakatani T, Nakano S, Matsui Y, Matsumura M|title = Severe optic neuropathy caused by dichloromethane inhalation|journal = J Ocul Pharmacol and Ther|volume = 24|issue = 6|pages = 607–612|year = 2008|pmid = 19049266|doi = 10.1089/jop.2007.0100}}</ref> and hepatitis.<ref>{{cite journal|author = Cordes DH, Brown WD, Quinn KM|title = Chemically induced hepatitis after inhaling organic solvents|journal = West J Med|volume = 148|issue = 4|pages = 458–460|year = 1988|pmid = 3388849|pmc = 1026148}}</ref> Prolonged skin contact can result in the dichloromethane dissolving some of the fatty tissues in skin, resulting in skin irritation or chemical burns.<ref>{{cite journal|author = Wells G, Waldron H|title = Methylene chloride burns|journal = Br J Ind Med|volume = 41|issue = 3|pages = 420|year = 1984|pmid = 6743591|pmc = 1009322}}</ref>

It may be [[carcinogen]]ic, as it has been linked to [[cancer]] of the [[lungs]], [[liver]], and [[pancreas]] in laboratory animals.<ref name="USDHHS">{{cite web|author=USDHHS|title=Toxicological Profile for Methylene Chloride|url=http://www.atsdr.cdc.gov/toxprofiles/tp14.pdf|accessdate=2006-09-10|format=PDF}}</ref> Dichloromethane crosses the placenta. [[Fetal]] toxicity in women who are exposed to it during [[pregnancy]] however has not been proven.<ref>{{cite journal|author = Bell B, Franks P, Hildreth N, Melius J|title = Methylene chloride exposure and birthweight in Monroe County, New York|journal = Environ Res|volume = 55|issue = 1|pages = 31–9|year = 1991|pmid = 1855488|doi = 10.1016/S0013-9351(05)80138-0}}</ref> In animal experiments it was fetotoxic at doses that were maternally toxic but no [[teratology|teratogenic]] effects were seen.<ref name="USDHHS"/>

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.<ref>{{cite web|url=http://www.europarl.europa.eu/news/expert/infopress_page/064-46096-012-01-03-911-20090113IPR46095-12-01-2009-2009-false/default_en.htm|title=Dichloromethane to be banned in paint-strippers|date=2009-01-14|accessdate=2009-01-15}}</ref> The ban will take effect by December 2010.{{Citation needed|date=August 2010}}

==References==
{{Reflist}}

==External links==
* {{ICSC|0058|00}}
* {{PGCH|0414}}
* [http://www.npi.gov.au/substances/dichloromethane/index.html National Pollutant Inventory - Dichloromethane Fact Sheet]
* [http://ptcl.chem.ox.ac.uk/MSDS/DI/dichloromethane.html MSDS at Oxford University]
* [http://ntp.niehs.nih.gov/ntp/roc/eleventh/profiles/s066dich.pdf Dichloromethane at National Toxicology Program]
* [http://www.inchem.org/documents/iarc/vol71/004-dichloromethane.html IARC Summaries & Evaluations Vol. 71 (1999)]

{{Halomethanes}}

[[Category:Organochlorides]]
[[Category:Halomethanes]]
[[Category:Aerosol propellants]]
[[Category:Hazardous air pollutants]]
[[Category:Refrigerants]]
[[Category:Halogenated solvents]]
[[Category:IARC Group 2B carcinogens]]

[[ar:ثنائي كلورو الميثان]]
[[bs:Metilen hlorid]]
[[cs:Dichlormethan]]
[[da:Metylenklorid]]
[[de:Dichlormethan]]
[[et:Metüleenkloriid]]
[[es:Cloruro de metileno]]
[[fr:Dichlorométhane]]
[[it:Diclorometano]]
[[he:דיכלורומתאן]]
[[lv:Metilēnhlorīds]]
[[lb:Dichloromethan]]
[[hu:Diklórmetán]]
[[nl:Dichloormethaan]]
[[ja:ジクロロメタン]]
[[pl:Chlorek metylenu]]
[[pt:Diclorometano]]
[[ru:Дихлорметан]]
[[fi:Dikloorimetaani]]
[[sv:Diklormetan]]
[[vi:Diclomêtan]]
[[zh:二氯甲烷]]
[[Category:2Fix]]