Chloromethane
300321
222656455
2008-06-30T13:41:36Z
12.240.60.198
{{Chembox new
| ImageFileL1 = Chloromethane.svg
| ImageSizeL1 = 100px
| ImageFileR1 = Chloromethane-3D-vdW.png
| ImageSizeR1 = 160px
| IUPACName = Chloromethane
| OtherNames = Monochloromethane, Methyl chloride, Artic, Freon 40, R 40, UN 1063
| Section1 = {{Chembox Identifiers
| CASNo = 74-87-3
| EINECS = 200-817-4
| PubChem = 6327
| SMILES = CCl
| 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)
| BoilingPt = -24.2 °C (249 K)
| Solubility = 5.325 g/l
| LogP = 0.91
| VaporPressure = 490 kPa (20 °C)
}}
| 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 [[haloalkanes]]. It was once widely used as a [[refrigeration|refrigerant]]. It is a colorless extremely flammable gas with a slightly sweet odor, which is, however, detected at possibly toxic levels. Due to concerns about its toxicity, it is no longer present in consumer products.
Methyl chloride 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.
== 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 ==
Formerly, chloromethane was a widely used [[refrigerant]], but due to its toxicity this use has been discontinued. Chloromethane was also once used for producing [[lead]]-based [[gasoline additive|additives for gasoline]], but [[leaded gasoline]] has been phased out in most of the industrialized world (an important exception being the former [[Soviet Union]]).
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 also employed as a 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 methyl chloride gas produces [[central nervous system]] effects similar to [[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 methyl chloride has been linked to [[birth defect]]s in mice. In humans, exposure to methyl chloride during [[pregnancy]] may cause the fetus' lower [[spine (anatomy)|spinal column]], [[pelvis]], and [[leg]]s to form incorrectly, but this has not been conclusively proven.
In [[1997]], a re-investigation of [[Boston|Boston's]] [[Cocoanut Grove fire|Cocoanut Grove]] nightclub fire cited a methyl chloride leak from a refrigerator as a major cause of that disaster.
== See also ==
* [[Halomethane]]
* [[Fluoromethane]]
* [[Bromomethane]]
* [[Iodomethane]]
== 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)]
[[Category:Organochlorides]]
[[Category:Halomethanes]]
[[Category:Refrigerants]]
[[Category:Halogenated solvents]]
[[Category:Hazardous air pollutants]]
[[Category:IARC Group 3 carcinogens]]
[[da:Metylklorid]]
[[de:Chlormethan]]
[[fr:Chlorométhane]]
[[it:Clorometano]]
[[lv:Hlormetāns]]
[[nl:Methylchloride]]
[[ja:クロロメタン]]
[[pt:Clorometano]]
[[fi:Metyylikloridi]]
[[zh:一氯甲烷]]