View source for Chloromethane

{{chembox
| Watchedfields = changed
| verifiedrevid = 322113753
| ImageFileL1 = Methyl Chloride.svg
| ImageSizeL1 = 100px
| ImageFileR1 = Chloromethane-3D-vdW.png
| ImageSizeR1 = 140px
| IUPACName = Chloromethane
| OtherNames = Monochloromethane, Methyl chloride, Artic, Freon 40, R 40, UN 1063
| Section1 = {{Chembox Identifiers
|   ChemSpiderID = 6087
| InChIKey = NEHMKBQYUWJMIP-UHFFFAOYAW
| CASNo = 74-87-3
|    CASNo_Ref = {{cascite}}
|   EINECS = 200-817-4
|   PubChem = 6327
|   SMILES = ClC
|   InChI = 1/CH3Cl/c1-2/h1H3
|   ChEBI = 36014
|   RTECS = PA6300000
  }}
| Section2 = {{Chembox Properties
|   Formula = CH<sub>3</sub>Cl
|   MolarMass = 50.49 g/mol
|   Appearance = Colorless gas with a faint sweet odor
|   Density = 2.22 kg/m<sup>3</sup> (0 °C)
|   MeltingPt = −97.7 °C (176 K) (-143.9 °F)
|   BoilingPt = -24.2 °C (249 K) (-11.6 °F)
|   Solubility = 5.325 g/l (25 °C)
|   LogP = 0.91
|   VaporPressure = 490 kPa (20 °C) ; 71 PSI (68°F)
  }}
| Section3 = {{Chembox Structure
|   MolShape = Tetrahedral
  }}
| Section4 = {{Chembox Hazards
|   EUClass = Extremely flammable ('''F+'''), Harmful ('''Xn'''), [[Carcinogen|Carc. Cat. 3]]
|   MainHazards = 
|   FlashPt = -46 °C
|   Autoignition = 625 °C
|   NFPA-H = 2
|   NFPA-F = 4
|   NFPA-R = 
|   NFPA-O = 
|   RPhrases = {{R10}}, {{R40}}, {{R48/20}}
|   SPhrases = {{S9}}, {{S16}}, {{S33}}
  }}
}}
'''Chloromethane''', also called '''methyl chloride''', '''R-40''' or '''HCC 40''', is a [[chemical compound]] of the group of [[organic compound]]s called [[haloalkane]]s. It was once widely used as a [[refrigeration|refrigerant]].  It is a colorless extremely flammable gas with a minorly sweet odor, which is, however, detected at possibly toxic levels.  Due to concerns about its toxicity, it is no longer present in consumer products.
Chloromethane was first synthesized by the French chemists [[Jean-Baptiste Dumas]] and [[Eugene Peligot]] in 1835 by boiling a mixture of [[methanol]], [[sulfuric acid]], and [[sodium chloride]].  This method is similar to that used today.

==Occurrence==
Chloromethane is the most abundant [[organohalogen]] – anthropogenic or natural – in the atmosphere.

===Marine===
Laboratory cultures of marine phytoplankton (''Phaeodactylum tricornutum'', ''Phaeocystis'' sp., ''Thalassiosira weissflogii'', ''Chaetoceros calcitrans'', ''Isochrysis'' sp., ''Porphyridium'' sp., ''Synechococcus'' sp., ''Tetraselmis'' sp., ''Prorocentrum'' sp., and ''Emiliana huxleyi'') produce CH<sub>3</sub>Cl, but in relatively insignificant amounts <ref>Scarratt MG, Moore RM (1996) Production of Methyl Chloride and Methyl Bromide in  Laboratory Cultures of Marine Phytoplankton. Mar Chem '''54''': 263</ref><ref>Scarratt MG, Moore RM (1998) Production of Methyl Bromide and Methyl Chloride in  Laboratory Cultures of Marine Phytoplankton II. Mar Chem '''59''': 311</ref>. An extensive study of 30 species of polar macroalgae revealed the release of
significant amounts of CH<sub>3</sub>Cl in only ''Gigartina skottsbergii'' and ''Gymnogongrus antarcticus''<ref>Laturnus F (2001) Marine Macroalgae in Polar Regions as Natural Sources for Volatile  Organohalogens. Environ Sci Pollut Res '''8''': 103</ref>.

===Biogenesis===
The [[salt marsh]] plant ''Batis maritima'' contains the enzyme methyl chloride [[transferase]] that catalyzes the synthesis of CH<sub>3</sub>Cl from S-adenosine-L-methionine and chloride <ref>Ni X, Hager LP (1998) cDNA Cloning of ''Batis maritima'' Methyl Chloride Transferase and  Purification of the Enzyme. Proc Natl Acad Sci USA '''95''': 12866</ref>. This protein has been purified and expressed in ''E. coli'', and seems to be present in other organisms such as white rot fungi (''Phellinus pomaceus''), red algae (''Endocladia muricata''), and the ice plant (''Mesembryanthemum crystallium''), each of which is a known CH<sub>3</sub>Cl producer <ref>Ni X, Hager LP (1998) cDNA Cloning of ''Batis maritima'' Methyl Chloride Transferase and  Purification of the Enzyme. Proc Natl Acad Sci USA '''95''': 12866</ref><ref>Ni X, Hager LP (1999) Expression of ''Batis maritima'' Methyl Chloride Transferase in  ''Escherichia coli''. Proc Natl Acad Sci USA '''96''': 3611</ref>.

== Production ==
Large amounts of chloromethane are produced naturally in the [[ocean]]s by the action of sunlight on [[biomass]] and [[chlorine]] in sea foam.  However, all chloromethane that is used in industry is produced synthetically.

Most chloromethane is prepared by reacting [[methanol]] with [[hydrochloric acid|hydrogen chloride]], according to the [[chemical equation]]

:[[methanol|CH<sub>3</sub>OH]] + [[hydrochloric acid|HCl]] → CH<sub>3</sub>Cl + [[water|H<sub>2</sub>O]]

This can be carried out either by bubbling hydrogen chloride gas through boiling methanol with or without a [[zinc chloride]] [[catalyst]], or by passing combined methanol and hydrogen chloride vapors over an [[alumina]] catalyst at 350 °C.

A smaller amount of chloromethane is produced by heating a mixture of [[methane]] and [[chlorine]] to over 400 °C.  However, this method also results in more highly chlorinated compounds such as [[methylene chloride]] and [[chloroform]] and is usually only used when these other products are also desired.

Further reaction of chloromethane with hydrochloric acid can produce [[dichloromethane]], [[trichloromethane]] (known as chloroform) and [[tetrachloromethane]] (also known as carbon tetrachloride).

== Uses ==
Chloromethane was a widely used [[refrigerant]], but its use has been discontinued due to its toxicity and flammability. Chloromethane was also once used for producing lead-based gasoline additives (tetramethyllead).

The most important use of chloromethane today is as a [[chemical intermediate]] in the production of [[silicone]] polymers.  Smaller quantities are used as a solvent in the manufacture of [[butyl rubber]] and in [[petroleum refining]].

Chloromethane is employed as a [[Methylation|methylating]] and chlorinating agent in [[organic chemistry]]. It is also used in a variety of other fields: as an extractant for [[petroleum|grease]]s, [[oil]]s and [[resin]]s, as a [[propellant]] and [[blowing agent]] in [[polystyrene]] foam production, as a [[local anesthetic]], as an intermediate in drug manufacturing, as a [[catalyst]] carrier in low-temperature [[polymerization]], as a fluid for thermometric and thermostatic equipment, and as a [[herbicide]].

== Safety ==
Inhalation of chloromethane gas produces [[central nervous system]] effects similar to [[drug intoxication]].  Victims may feel drowsy, dizzy, or confused and have difficulty breathing, with gasping and choking, walking or speaking.  At higher concentrations, [[paralysis]], [[seizure]]s, and [[coma]] may result.

In case of ingestion nausea and vomiting may result. Skin contact when in the form of a refrigerated liquid may result in [[frostbite]]. Contact with eyes may result in dim vision, widely dilated pupils that react slowly to changes in light.

Chronic exposure to chloromethane has been linked to [[birth defect]]s in mice.  In humans, exposure to chloromethane during [[pregnancy]] may cause the fetus' lower [[spine (anatomy)|spinal column]], [[pelvis]], and [[leg]]s to form incorrectly, but this has not been conclusively demonstrated.

In 1997, a re-investigation of [[Boston|Boston's]] [[Cocoanut Grove fire|Cocoanut Grove]] nightclub fire in 1942 cited a chloromethane leak from a refrigerator as a major cause of that disaster.

==References==
 <references/>

==External links==
*{{ICSC|0419|04}}
*{{PGCH|0403}}
*[http://ptcl.chem.ox.ac.uk/MSDS/CH/chloromethane.html MSDS at Oxford University]
*[http://www.inchem.org/documents/sids/sids/CLMETHANE.pdf Data sheet at inchem.org]
*[http://www.inchem.org/documents/pims/chemical/metchlor.htm Toxicological information]
*[http://www.eco-usa.net/toxics/clmethan.shtml Information about chloromethane]
*[http://www.inchem.org/documents/cicads/cicads/cicad28.htm Concise International Chemical Assessment Document 28 on chloromethane]
*[http://www.inchem.org/documents/iarc/vol71/026-methylchloride.html IARC Summaries & Evaluations Vol. 71 (1999)]

{{Halomethanes}}

[[Category:Greenhouse gases]]
[[Category:Halogenated solvents]]
[[Category:Halomethanes]]
[[Category:Hazardous air pollutants]]
[[Category:IARC Group 3 carcinogens]]
[[Category:Organochlorides]]
[[Category:Refrigerants]]

[[cs:Chlormethan]]
[[da:Metylklorid]]
[[de:Chlormethan]]
[[el:Μεθυλοχλωρίδιο]]
[[es:Clorometano]]
[[fr:Chlorométhane]]
[[it:Clorometano]]
[[lv:Hlormetāns]]
[[lb:Monochloromethan]]
[[hu:Klórmetán]]
[[mk:Хлорометан]]
[[nl:Chloormethaan]]
[[ja:クロロメタン]]
[[pl:Chlorometan]]
[[pt:Clorometano]]
[[ru:Хлорметан]]
[[fi:Metyylikloridi]]
[[sv:Klormetan]]
[[th:คลอโรมีเทน]]
[[uk:Хлорметан]]
[[zh:氯甲烷]]
[[Category:2Fix]]