View source for Chemistry:Chloromethane

{{Short description|Chemical compound formerly used as a refrigerant}}
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 411542354
| ImageFile = Natta projection of chloromethane.svg
| ImageFile_Ref = {{chemboximage|correct|??}}
| ImageSize = 100
| ImageName = Stereo, skeletal formula of chloromethane with all explicit hydrogens added
| ImageFileL1 = Chloromethane-3D-balls.png
| ImageFileL1_Ref = {{chemboximage|correct|??}}
| ImageNameL1 = Ball and stick model of chloromethane
| ImageFileR1 = Chloromethane-3D-vdW.png
| ImageFileR1_Ref = {{chemboximage|correct|??}}
| ImageNameR1 = Spacefill model of chloromethane
| PIN = Chloromethane<ref>{{cite book |author=[[Organization:International Union of Pure and Applied Chemistry|International Union of Pure and Applied Chemistry]] |date=2014 |title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 |publisher=[[Organization:Royal Society of Chemistry|The Royal Society of Chemistry]] |pages=1033 |doi=10.1039/9781849733069 |isbn=978-0-85404-182-4}}</ref>
| OtherNames = {{unbulleted list|Refrigerant-40|R-40<ref name=GESTIS>{{GESTIS|ZVG=11220}}</ref> |Methyl chloride<ref name=GESTIS/>|Monochloromethane<ref name=GESTIS/>}}
|Section1={{Chembox Identifiers
| Abbreviations =
| CASNo = 74-87-3
| CASNo_Ref = {{cascite|correct|CAS}}
| PubChem = 6327
| ChemSpiderID = 6087
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| UNII = A6R43525YO
| UNII_Ref = {{fdacite|correct|FDA}}
| EINECS = 200-817-4
| UNNumber = 1063
| KEGG = C19446
| KEGG_Ref = {{keggcite|changed|kegg}}
| MeSHName = Methyl+Chloride
| ChEBI = 36014
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 117545
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| RTECS = PA6300000
| Beilstein = 1696839
| Gmelin = 24898
| SMILES = CCl
| StdInChI = 1S/CH3Cl/c1-2/h1H3
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = NEHMKBQYUWJMIP-UHFFFAOYSA-N
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
}}
|Section2={{Chembox Properties
| C=1 | H=3 | Cl=1
| Appearance = Colorless gas
| Odor = Faint, sweet odor<ref name=PGCH/>
| Density = 1.003 g/mL (-23.8&nbsp;°C, liquid)<ref name=GESTIS/> 2.3065 g/L (0&nbsp;°C, gas)<ref name=GESTIS/>
| MeltingPtC = -97.4
| MeltingPt_ref = <ref name=GESTIS/>
| BoilingPtC = -23.8
| BoilingPt_ref = <ref name=GESTIS/>
| Solubility = 5.325 g L<sup>−1</sup>
| LogP = 1.113
| VaporPressure = 506.09 kPa (at {{convert|20|C}})
| HenryConstant = 940 nmol Pa<sup>−1</sup> kg<sup>−1</sup>
| MagSus = -32.0·10<sup>−6</sup> cm<sup>3</sup>/mol
}}
|Section3={{Chembox Structure
| Coordination = Tetragonal
| MolShape = Tetrahedron
| Dipole = 1.9 D
}}
|Section4={{Chembox Thermochemistry
| DeltaHf = −83.68 kJ mol<sup>−1</sup>
| DeltaHc = −764.5–−763.5 kJ mol<sup>−1</sup>
| Entropy = 234.36 J K<sup>−1</sup> mol<sup>−1</sup>
}}
|Section5={{Chembox Hazards
| GHSPictograms = {{gHS flame}} {{gHS health hazard}}
| GHSSignalWord = '''DANGER'''
| HPhrases = {{h-phrases|220|351|373}}
| PPhrases = {{p-phrases|210|281|410+403}}
| NFPA-H = 2
| NFPA-F = 4
| NFPA-R = 0
| FlashPtC = −20
| FlashPt_ref = <ref name=GESTIS/>
| AutoignitionPtC = 625
| AutoignitionPt_ref = <ref name=GESTIS/>
| ExploLimits = 8.1%-17.4%<ref name=PGCH/>
| LD50 = 150-180 mg/kg (oral, rat)<ref name=GESTIS/><br>5.3 mg/L/4 h (inhalation, rat)<ref name=GESTIS/>
| PEL = TWA 100 ppm C 200 ppm 300 ppm (5-minute maximum peak in any 3 hours)<ref name=PGCH>{{PGCH|0403}}</ref>
| IDLH = Ca [2000 ppm]<ref name=PGCH/>
| REL = Ca<ref name=PGCH/>
| MainHazards =
| LC50 = 72,000 ppm (rat, 30 min)<br />2200 ppm (mouse, 6 hr)<br />2760 ppm (mammal, 4 hr)<br />2524 ppm (rat, 4 hr)<ref name=IDLH>{{IDLH|74873|Methyl chloride}}</ref>
| LCLo = 20,000 ppm (guinea pig, 2 hr)<br />14,661 ppm (dog, 6 hr)<ref name=IDLH/>
}}
|Section6={{Chembox Related
| OtherFunction_label = alkanes
| OtherFunction = {{unbulleted list|[[Chemistry:Chloroiodomethane|Chloroiodomethane]]|[[Chemistry:Bromochloromethane|Bromochloromethane]]|[[Chemistry:Dibromochloromethane|Dibromochloromethane]]}}
| OtherCompounds = [[Chemistry:2-Chloroethanol|2-Chloroethanol]]
}}
}}

'''Chloromethane''', also called '''methyl chloride''', '''Refrigerant-40''', '''R-40''' or '''HCC 40''', is an [[Chemistry:Organic compound|organic compound]] with the chemical formula {{chem2|CH3Cl}}. One of the [[Chemistry:Haloalkane|haloalkane]]s, it is a colorless, sweet-smelling, flammable gas. Methyl chloride is a crucial [[Biology:Reagent|reagent]] in industrial chemistry, although it is rarely present in consumer products,<ref name=Ross/> and was formerly utilized as a [[Chemistry:Refrigerant|refrigerant]].  Most chloromethane is biogenic.

==Occurrence==
Chloromethane is an abundant organohalogen, anthropogenic or natural, in the atmosphere.  Natural sources produce an estimated 4,100,000,000 kg/yr.<ref>{{cite book|title=Naturally Occurring Organohalogen Compounds|editor=
Kinghorn, A. Douglas.; Falk, Heinz, Gibbons, Simon; Asakawa, Yoshinori; Liu, Ji-Kai; Dirsch, Verena M. Cham|publisher=Springer Nature|location=Switzerland|year=2023|
ISBN= 3-031-26629-3|author=Gribble, Gordon|series=Progress in the Chemistry of Organic Natural Products }}</ref>
===Marine===
Laboratory cultures of marine [[Earth:Phytoplankton|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>{{cite journal |vauthors=Scarratt MG, Moore RM| year = 1996 | title = Production of Methyl Chloride and Methyl Bromide in Laboratory Cultures of Marine Phytoplankton | journal = Mar Chem | volume = 54 | pages = 263–272 | doi = 10.1016/0304-4203(96)00036-9 | issue = 3–4| bibcode = 1996MarCh..54..263S }}</ref><ref>{{cite journal |vauthors=Scarratt MG, Moore RM| year = 1998 | title = Production of Methyl Bromide and Methyl Chloride in Laboratory Cultures of Marine Phytoplankton II | journal = Mar Chem | volume = 59 | pages = 311–320 | doi = 10.1016/S0304-4203(97)00092-3 | issue = 3–4| bibcode = 1998MarCh..59..311S }}</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>{{cite journal | author = Laturnus F | year = 2001 | title = Marine Macroalgae in Polar Regions as Natural Sources for Volatile Organohalogens | journal = Environ Sci Pollut Res | volume = 8 | pages = 103–108 | doi = 10.1007/BF02987302 | pmid = 11400635 | issue = 2| s2cid = 570389 }}</ref>

===Biogenesis===
The [[Earth:Salt marsh|salt marsh]] plant ''[[Biology:Batis maritima|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 name=Ni >{{cite journal |vauthors=Ni X, Hager LP| year = 1998 | title = cDNA Cloning of ''Batis maritima'' Methyl Chloride Transferase and Purification of the Enzyme | journal = Proc Natl Acad Sci USA | volume = 95 | pages = 12866–71 | doi = 10.1073/pnas.95.22.12866 | pmid = 9789006 | issue = 22 | pmc = 23635| bibcode = 1998PNAS...9512866N | doi-access = free }}</ref> This protein has been purified and expressed in ''E. coli'', and seems to be present in other organisms such as white rot fungi (''[[Biology:Phellinus pomaceus|Phellinus pomaceus]]''), red algae (''[[Biology:Endocladia muricata|Endocladia muricata]]''), and the ice plant (''[[Biology:Mesembryanthemum crystallinum|Mesembryanthemum crystallinum]]''), each of which is a known CH<sub>3</sub>Cl producer.<ref name=Ni/><ref>{{cite journal |vauthors=Ni X, Hager LP| year = 1999 | title = Expression of ''Batis maritima'' Methyl Chloride Transferase in ''Escherichia coli'' | journal = Proc Natl Acad Sci USA | volume = 96 | pages = 3611–5 | doi = 10.1073/pnas.96.7.3611 | pmid = 10097085 | issue = 7 | pmc = 22342| bibcode = 1999PNAS...96.3611N | doi-access = free }}</ref>

===Sugarcane and the emission of methyl chloride===
In the sugarcane industry, the organic waste is usually burned in the power [[Physics:Cogeneration|cogeneration]] process. When contaminated by chloride, this waste burns, releasing methyl chloride in the atmosphere.<ref name="RefF">{{cite journal |title= Global chlorine emissions from biomass burning: Reactive Chlorine Emissions Inventory |journal= Journal of Geophysical Research: Atmospheres |volume= 104 |pages= 8373–8389 |last1= Lobert |first1= Jurgen |last2= Keene |first2=Willian |last3= Yevich |first3=Jennifer |doi=10.1029/1998JD100077 |year=1999 |issue= D7 |bibcode=1999JGR...104.8373L|doi-access= free }}</ref>

===Interstellar detections===
Chloromethane has been detected in the low-mass Class 0 protostellar binary, [[Astronomy:IRAS 16293-2422|IRAS 16293'''–'''2422]], using the [[Astronomy:Atacama Large Millimeter Array|Atacama Large Millimeter Array]] (ALMA). It was also detected in the comet 67P/Churyumov–Gerasimenko (67P/C-G) using the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument on the [[Engineering:Rosetta (spacecraft)|Rosetta]] spacecraft.<ref>{{Cite web | url=https://www.eso.org/public/images/eso1732e/ |title = ALMA and Rosetta Detect Freon-40 in Space}}</ref> The detections reveal that chloromethane can be formed in star-forming regions before planets or life is formed.{{cn|date=October 2023}}

[[File:ALMA and Rosetta Detect Freon-40 in Space.jpg|thumb|left|Chloromethane has been detected in space.<ref>{{cite web|title=ALMA and Rosetta Detect Freon-40 in Space - Dashing Hopes that Molecule May be Marker of Life|url=https://www.eso.org/public/news/eso1732/|website=eso.org|access-date=3 October 2017}}</ref>]]

==Production==
Chloromethane was first synthesized by the French chemists Jean-Baptiste Dumas and Eugene Peligot in 1835 by boiling a mixture of [[Chemistry:Methanol|methanol]], [[Chemistry:Sulfuric acid|sulfuric acid]], and [[Chemistry:Sodium chloride|sodium chloride]].  This method is the forerunner for that used today, which uses [[Chemistry:Hydrogen chloride|hydrogen chloride]] instead of sulfuric acid and sodium chloride.<ref>{{Cite web |title=Chloromethane |url=https://www.acs.org/content/acs/en/molecule-of-the-week/archive/c/chloromethane.html |access-date=2022-05-13 |website=American Chemical Society |language=en}}</ref>

Chloromethane is produced commercially by treating [[Chemistry:Methanol|methanol]] with [[Chemistry:Hydrochloric acid|hydrochloric acid]] or hydrogen chloride, according to the [[Chemistry:Chemical equation|chemical equation]]:<ref name=Ross>{{Ullmann | last1 = Rossberg | first1 = M. | last2 = Lendle | first2 = W. | last3 = Pfleiderer | first3 = G. | last4 = Tögel | first4 = A. | last5 = Dreher | first5 = E. L. | last6 = Langer | first6 = E. | last7 = Rassaerts | first7 = H. | last8 = Kleinschmidt | first8 = P. | last9 = Strack | first9 = H. | last10 = Cook | first10 = R. | last11 = Beck | first11 = U. | last12 = Lipper | first12 = K.-A. | last13 = Torkelson | first13 = T.R.| last14 = Löser | first14 = E. | last15 = Beutel | first15 = K.K. | last16 = Mann | first16 = T. | title= Chlorinated Hydrocarbons| year = 2006 | isbn = 3527306730 | doi=10.1002/14356007.a06_233.pub2 | pmc = }}</ref>

: CH<sub>3</sub>OH + HCl  →  CH<sub>3</sub>Cl + H<sub>2</sub>O

A smaller amount of chloromethane is produced by treating a mixture of [[Chemistry:Methane|methane]] with [[Chemistry:Chlorine|chlorine]] at elevated temperatures.  This method, however, also produces more highly chlorinated compounds such as [[Chemistry:Dichloromethane|dichloromethane]], [[Chemistry:Chloroform|chloroform]], and [[Chemistry:Carbon tetrachloride|carbon tetrachloride]].  For this reason, methane chlorination is usually only practiced when these other products are also desired.  This chlorination method also cogenerates hydrogen chloride, which poses a disposal problem.<ref name=Ross/>

: {{Chem2|CH4 + Cl2 -> CH3Cl + HCl}}<br>
: {{Chem2|CH3Cl + Cl2 -> CH2Cl2 + HCl}}<br>
: {{Chem2|CH2Cl2 + Cl2 -> CHCl3 + HCl}}<br>
: {{Chem2|CHCl3 + Cl2 -> CCl4 + HCl}}

==Dispersion in the environment==

[[File:CH3Cl_mm.png|thumb|left|CH<sub>3</sub>Cl measured by the Advanced Global Atmospheric Gases Experiment ([http://agage.mit.edu/ AGAGE]) in the lower atmosphere ([[Earth:Troposphere|troposphere]]) at stations around the world. Abundances are given as pollution free monthly mean mole fractions in parts-per-trillion.]]

Most of the methyl chloride present in the environment ends up being released to the [[Astronomy:Atmosphere|atmosphere]]. After being released into the air, the atmospheric lifetime of this substance is about 10 months with multiple natural sinks, such as ocean, transport to the stratosphere, soil, etc.<ref name ="RefA">{{cite journal|vauthors=Fabian P, Borchers R, Leifer R, Subbaraya BH, Lal S, Boy M |title=Global stratospheric distribution of halocarbons |journal= Atmospheric Environment |volume=30 |number=10/11 |pages=1787–1796 |date=1996|doi=10.1016/1352-2310(95)00387-8 |bibcode=1996AtmEn..30.1787F }}</ref><ref>{{cite journal|vauthors=Zhang W, Jiao Y, Zhu R, Rhew RC |title= Methyl Chloride and Methyl Bromide Production and Consumption in Coastal Antarctic Tundra Soils Subject to Sea Animal Activities|journal= Environmental Science & Technology |volume=54 |number=20 |pages=13354–13363 |date=2020|doi=10.1021/acs.est.0c04257|pmid= 32935983|bibcode= 2020EnST...5413354Z|s2cid= 221745138}}</ref><ref>{{cite journal|vauthors=Carpenter LJ, Reimann S, Burkholder JB, Clerbaux C, Hall BD, Hossaini R, Laube JC, Yvon-Lewis SA |title= Update on ODSs and Other Gases of Interest to the Montreal Protocol|journal= WMO (World Meteorological Organization), Scientific Assessment of Ozone Depletion: 2014, Global Ozone Research and Monitoring Project |date=2014|url=https://www.esrl.noaa.gov/csl/assessments/ozone/2014/summary/ch1.html}}</ref>

On the other hand, when the methyl chloride emitted is released to water, it will be rapidly lost by volatilization. The [[Physics:Half-life|half-life]] of this substance in terms of volatilization in the river, lagoon and lake is 2.1 h, 25 h and 18 days, respectively.<ref>{{cite book|last1=Lyman |first1=Warren |last2=Rosenblatt |first2=David |last3=Reehl |first3=William |date=1982 |title=Handbook of chemical property estimation methods|publisher=McGraw-Hill |isbn=9780070391758 |url=https://archive.org/details/handbookofchemic0000lyma |url-access=registration }}</ref><ref name="RefB">{{cite journal|author=Agency for Toxic Substances and Disease Registry (ATSDR) |title=Toxicological profile for chloromethane |date=1990}}</ref>

The amount of methyl chloride in the [[Earth:Stratosphere|stratosphere]] is estimated to be 2 x 10<sup>6</sup> tonnes per year, representing 20-25% of the total amount of chlorine that is emitted to the stratosphere annually.<ref name ="RefC">{{cite journal|vauthors=Borchers R, Gunawardena R, Rasmussen RA |title=Long term trend of selected halogenated hydrocarbons |pages=259–262 |date=1994}}</ref><ref name ="RefD">{{cite journal|vauthors=Crutzen PJ, Gidel LT |title=The tropospheric budgets of the anthropogenic chlorocarbons CO, CH4, CH3Cl and the effect of various NOx sources on tropospheric ozone |journal=Journal of Geophysical Research |volume=88 |pages=6641–6661 |date=1983|doi=10.1029/JC088iC11p06641 }}</ref>

==Uses==
Large scale use of chloromethane is for the production of [[Chemistry:Dimethyldichlorosilane|dimethyldichlorosilane]] and related [[Chemistry:Organosilicon compound|organosilicon compound]]s.<ref name=Ross/> These compounds arise via the [[Chemistry:Direct process|direct process]]. The relevant reactions are (Me = CH<sub>3</sub>):
:x MeCl + Si → Me<sub>3</sub>SiCl, Me<sub>2</sub>SiCl<sub>2</sub>, MeSiCl<sub>3</sub>, Me<sub>4</sub>Si<sub>2</sub>Cl<sub>2</sub>, ...
[[Chemistry:Dimethyldichlorosilane|Dimethyldichlorosilane]] (Me<sub>2</sub>SiCl<sub>2</sub>) is of particular value as a precursor to [[Chemistry:Silicone|silicone]]s, but [[Chemistry:Trimethylsilyl chloride|trimethylsilyl chloride]] (Me<sub>3</sub>SiCl) and [[Chemistry:Methyltrichlorosilane|methyltrichlorosilane]] (MeSiCl<sub>3</sub>) are also valuable.
Smaller quantities are used as a solvent in the manufacture of [[Chemistry:Butyl rubber|butyl rubber]] and in petroleum refining.

Chloromethane is employed as a [[Biology:Methylation|methylating]] and chlorinating agent, e.g. the production of methylcellulose. It is also used in a variety of other fields: as an extractant for [[Chemistry:Petroleum|grease]]s, [[Chemistry:Oil|oil]]s, and resins, as a [[Physics:Propellant|propellant]] and [[Physics:Blowing agent|blowing agent]] in [[Chemistry:Polystyrene|polystyrene]] foam production, as a [[Medicine:Local anesthetic|local anesthetic]], as an intermediate in drug manufacturing, as a [[Chemistry:Catalyst|catalyst]] carrier in low-temperature [[Chemistry:Polymerization|polymerization]], as a fluid for thermometric and thermostatic equipment, and as a [[Biology:Herbicide|herbicide]].

===Obsolete applications===
Chloromethane was a widely used [[Chemistry:Refrigerant|refrigerant]], but its use has been discontinued. Chloromethane was also once used for producing lead-based gasoline additives (tetramethyllead).

==Safety==
Inhalation of chloromethane gas produces [[Biology:Central nervous system|central nervous system]] effects similar to [[Medicine:Alcohol intoxication|alcohol intoxication]]. The TLV is 50 ppm and the MAC is the same. Prolonged exposure may have mutagenic effects.<ref name=Ross/>

==See also==
* [[Chemistry:Bromomethane|bromomethane]]
* [[Chemistry:Dichloromethane|dichloromethane]]
* [[Chemistry:Chloroform|trichloromethane]]
* [[Chemistry:Carbon tetrachloride|tetrachloromethane]]
==References==
{{reflist}}

==External links==
* {{ICSC|0419|04}}
* {{PGCH|0403}}
* [https://web.archive.org/web/20070927210420/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]
* [https://web.archive.org/web/20070927195226/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)]
* Ohligschläger et al. (2020). Chloromethanes. In Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a06 233.pub4

{{halomethanes}}


[[Category:Greenhouse gases]]
[[Category:Halogenated solvents]]
[[Category:Halomethanes]]
[[Category:Hazardous air pollutants]]
[[Category:Chloroalkanes]]
[[Category:Refrigerants]]
[[Category:Halogen-containing natural products]]
[[Category:Methylating agents]]

{{Sourceattribution|Chloromethane}}