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			{{distinguish|Methyl isocyanide}}
			{{Use dmy dates|date=July 2018}}
	{{Chembox		{{Chembox
			| Watchedfields = changed
	| verifiedrevid = 444012845
			| verifiedrevid = 451299397
	| ImageFile = Methyl isocyanate.svg		| ImageFile = Methyl isocyanate.svg
	| ImageSize =		| ImageSize =
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	| ImageSize1 =		| ImageSize1 =
	| ImageName1 = Methyl isocyanate		| ImageName1 = Methyl isocyanate
			| PIN = Isocyanatomethane <!-- This is a change from previous recommendations. Methyl isocyanate (MIC) is an organic compound with the molecular formula CH3NCO. Synonyms are isocyanatomethane and methyl carbylamine. Methyl isocyanate is an intermediate chemical in the production of carbamate pesticides (such as carbaryl, carbofuran, methomyl, and aldicarb). It has also been used in the production of rubbers and adhesives. As an extremely toxic and irritating compound, it is very hazardous to human health. It was the principal toxicant involved in the infamous Bhopal gas disaster, which officially killed around 16,000 people in total. It is also a very potent lachrymatory agent.
	| IUPACName = Methyl isocyanate
	| OtherNames = isocyanatomethane, methyl carbylamine
			Preferred IUPAC names are generated substituively using the prefix 'isocyanato' attached directly to a parent hydride. -->
	| Abbreviations = MIC
			| OtherNames = Methyl carbylamine<br />MIC
	| Section1 = {{Chembox Identifiers
			|Section1={{Chembox Identifiers
			| IUPHAR_ligand = 6290
	| CASNo_Ref = {{cascite|correct|CAS}}		| CASNo_Ref = {{cascite|correct|CAS}}
	| CASNo = 624-83-9		| CASNo = 624-83-9
			| UNII_Ref = {{fdacite|correct|FDA}}
	| PubChem = 12228
			| UNII = C588JJ4BV9
	| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
			| PubChem = 12228
			| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
	| ChemSpiderID = 11727		| ChemSpiderID = 11727
	| ChEBI_Ref = {{ebicite|correct|EBI}}		| ChEBI_Ref = {{ebicite|correct|EBI}}
	| ChEBI = 59059		| ChEBI = 59059
	| SMILES = O=C=N/C		| SMILES = O=C=NC
	| StdInChI_Ref = {{stdinchicite|correct|chemspider}}		| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
	| StdInChI=1S/C2H3NO/c1-3-2-4/h1H3		| StdInChI =1S/C2H3NO/c1-3-2-4/h1H3
	| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}		| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
	| StdInChIKey = HAMGRBXTJNITHG-UHFFFAOYSA-N		| StdInChIKey = HAMGRBXTJNITHG-UHFFFAOYSA-N
	}}		}}
	| Section2 = {{Chembox Properties		|Section2={{Chembox Properties
	| Formula = C<sub>2</sub>H<sub>3</sub>NO		| Formula =C<sub>2</sub>H<sub>3</sub>NO
	| MolarMass = 57.051 g/mol		| MolarMass = 57.051 g/mol
	| Appearance =		| Appearance = Colorless liquid
			| Odor = Sharp, pungent odor<ref name=PGCH/>
	| Density = 0.9230 g/cm<sup>3</sup> at 27°C
			| Density = 0.9230 g/cm<sup>3</sup> at 27 °C
	| MeltingPt = -45°C
	| BoilingPt = 39.5°C		| MeltingPtC = −45
	| Solubility = very soluble<ref name="hand">{{RubberBible87th}}</ref>		| MeltingPt_ref = <ref name="hand">{{RubberBible87th}}</ref>
			| BoilingPtC = 38.3 - 41
			| BoilingPt_ref = <ref name="hand"/>
			| Solubility = 10% (15°C)<ref name=PGCH/>
	| VaporPressure = 57.7 ]		| VaporPressure = 57.7 ]
	}}		}}
	| Section3 = {{Chembox Structure		|Section3={{Chembox Structure
	| CrystalStruct =		| CrystalStruct =
	| Coordination =		| Coordination =
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	| Dipole = 2.8 ]		| Dipole = 2.8 ]
	}}		}}
	| Section4 = {{Chembox Thermochemistry		|Section4={{Chembox Thermochemistry
	| DeltaHf = -92.0 ]<ref name="hand"/>		| DeltaHf = −92.0 ]<ref name="hand"/>
			| DeltaHc = -1.1275E+06 ]<ref>{{cite journal |author=Lemoult |journal=Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences |date=1898 |volume=126 |page=43}}</ref>
	| DeltaHc =
	| Entropy =		| Entropy =
	| HeatCapacity =		| HeatCapacity =
	}}		}}
	| Section8 = {{Chembox Hazards		|Section8={{Chembox Hazards
	| MainHazards =		| MainHazards =
			| GHSPictograms = {{gHS skull and crossbones}} {{gHS health hazard}} {{gHS flame}} {{gHS corrosion}} {{GHS07}}
	| NFPA-H = 4
			| HPhrases = {{h-phrases|225|300|311|315|317|318|330|334|335|361d}}
	| NFPA-F = 3
			| PPhrases = {{p-phrases|201|202|210|233|240|241|242|243|260|261|264|270|271|272|280|281|284|285|301+310|302+352|303+361+353|304+340|304+341|305+351+338|308+313|310|312|320|321|322|330|332+313|333+313|342+311|361|362|363|370+378|403+233|403+235|405|501}}
	| NFPA-R = 2
	| NFPA-O = W		| NFPA-H = 4
	| FlashPt = -7°C		| NFPA-F = 3
	| Autoignition = 534°C		| NFPA-R = 3
			| NFPA-S = W
	| ExploLimits = 5.3 - 26%<ref name="hand"/>
			| FlashPtC = −7
	}}
			| AutoignitionPtC = 534
	| Section9 = {{Chembox Related
			| ExploLimits = 5.3–26%<ref name="hand"/>
	| OtherCpds = ]
			| IDLH = 3 ppm<ref name=PGCH>{{PGCH|0423}}</ref>
			| LC50 = 6.1 ppm (rat, 6 hr)<br/>12.2 ppm (mouse, 6 hr)<br/>5.4 ppm (guinea pig, 6 hr)<br/>21 ppm (rat, 2 hr)<ref name=IDLH>{{IDLH|624839|Methyl isocyanate}}</ref>
			| LD50 = 120 mg/kg (oral, mouse)<br/>51.5 mg/kg (oral, rat)<ref name=IDLH/>
			| REL = TWA 0.02 ppm (0.05 mg/m<sup>3</sup>) <ref name=PGCH/>
			| PEL = TWA 0.02 ppm (0.05 mg/m<sup>3</sup>) <ref name=PGCH/>
			}}<ref>{{cite web |url=http://www.nmsu.edu/safety/programs/chem_safety/NFPA-ratingJ-R.htm |title=NFPA Hazard Rating Information for Common Chemicals |publisher=nmsu.edu |access-date=2021-06-10 |url-status=dead |archive-url=https://web.archive.org/web/20150217040510/http://www.nmsu.edu/safety/programs/chem_safety/NFPA-ratingJ-R.htm |archive-date=2015-02-17}}</ref>
			|Section9={{Chembox Related
			| OtherCompounds = ]
	}}		}}
	}}		}}
	'''Methyl isocyanate''' ('''MIC''') is an organic compound with the molecular formula C<sub>2</sub>H<sub>3</sub>NO, arranged as H<sub>3</sub>C-N=C=O. Synonyms are isocyanatomethane, methyl carbylamine, and MIC. Methyl isocyanate is an intermediate chemical in the production of ] ]s (such as ], ], ], and ]). It has also been used in the production of ]s and ]s. As a highly ] and irritating material, it is hazardous to human health, and was involved in the ] which killed nearly 8,000 people initially and approximately 17,000 people in total.<ref name="irs">{{cite journal | doi = 10.1186/1476-069X-4-6 | journal = Environmental Health | year = 2005 | last1 = Broughton | first1 = Edward | volume = 4 | pages = 6 | pmid = 15882472 | title = The Bhopal disaster and its aftermath: a review | issue = 1 | pmc = 1142333}}</ref><ref>{{cite web |url=http://www.lakareformiljon.org/images/stories/dokument/2009/bhopal_gas_disaster.pdf |title=Chemical Industry and Public Health&nbsp;— Bhopal as an example |last=Eckerman |first=Ingrid |year=2001}}</ref><ref>{{cite book |last=Eckerman |first=Ingrid |title=The Bhopal Saga - Causes and Consequences of the World's Largest Industrial Disaster |url=http://www.eckerman.nu/default.cfm?page=The%20Bhopal%20Saga |year=2004 |publisher=Universities Press |location=India |isbn=81-7371-515-7 }}</ref><ref>{{cite web |url=http://history1900s.about.com/od/1980s/qt/bhopal.htm |first=Jennifer |last=Rosenberg |publisher=About.com |title=At 1984 - Huge Poison Gas Leak in Bhopal, India |accessdate=2008-07-10}}</ref>		'''Methyl isocyanate''' ('''MIC''') is an ] with the molecular formula CH<sub>3</sub>NCO. Synonyms are '''isocyanatomethane''' and '''methyl carbylamine'''. Methyl isocyanate is an intermediate chemical in the production of ] ]s and Haffmann Bromamide Degradation (such as ], ], ], and ]). It has also been used in the production of ]s and ]s. As an extremely ] and irritating compound, it is very hazardous to human health. MIC was the principal toxicant involved in the ], which short-term killed 4,000–8,000 people and caused permanent injury and premature deaths to approximately 15,000-20,000.<ref name="irs">{{cite journal |vauthors=Broughton E |title=The Bhopal disaster and its aftermath: a review |journal=Environmental Health |volume=4 |issue=1 |pages=6 |date=May 2005 |pmid=15882472 |pmc=1142333 |bibcode=2005EnvHe...4....6B |doi=10.1186/1476-069X-4-6 |doi-access=free}}</ref><ref>{{cite journal |vauthors=Eckerman I |title=Chemical Industry and Public Health — Bhopal as an example |journal=MPH |year=2001 |volume=2001 |issue=24 |publisher=Nordic School of Public Health |location=Göteborg, Sweden |issn=1104-5701 |url=http://www.lakareformiljon.org/images/stories/dokument/2009/bhopal_gas_disaster.pdf |url-status=live |archive-url=https://web.archive.org/web/20121030030142/http://www.lakareformiljon.org/images/stories/dokument/2009/bhopal_gas_disaster.pdf |archive-date=2012-10-30}}</ref><ref>{{cite book |vauthors=Eckerman I |title=The Bhopal Saga - Causes and Consequences of the World's Largest Industrial Disaster |url=http://www.eckerman.nu/default.cfm?page=The%20Bhopal%20Saga |year=2004 |publisher=Universities Press |location=India |isbn=81-7371-515-7 |url-status=dead |archive-url=https://web.archive.org/web/20070610212157/http://www.eckerman.nu/default.cfm?page=The%20Bhopal%20Saga |archive-date=2007-06-10}}</ref><ref>{{cite web |url=http://history1900s.about.com/od/1980s/qt/bhopal.htm |vauthors=Rosenberg J |publisher=About.com |title=At 1984 - Huge Poison Gas Leak in Bhopal, India |access-date=2008-07-10 |url-status=live |archive-url=https://web.archive.org/web/20071202051803/http://history1900s.about.com/od/1980s/qt/bhopal.htm |archive-date=2007-12-02}}</ref><ref name="Eckerman2013">{{cite book |vauthors=Eckerman I |chapter=Bhopal Gas Catastrophe 1984: Causes and Consequences |publisher=Elsevier |title=Reference Module in Earth Systems and Environmental Sciences |pages=272–287 |year=2013 |doi=10.1016/B978-0-12-409548-9.01903-5|isbn=978-0-12-409548-9}}</ref> It is also a very potent ].<ref name=Kimmerle />
	==Physical properties==		== Physical properties ==
	Methyl isocyanate (MIC) is a clear, colorless, ], sharp-smelling liquid. It is highly flammable, boils at 39.1°C and has a low ].<ref name="Union Carbide 1967">Union Carbide Corporation ''"Methyl Isocyanate"'' '''Product Information Publication''', F-41443, November 1967.</ref> Methyl isocyanate is soluble in water to 6–10 parts per 100 parts, but it reacts with the water (see ]).		Methyl isocyanate is a colorless, poisonous, ] (] agent), flammable liquid.<ref name="Union Carbide 1967">Union Carbide Corporation "Methyl Isocyanate" Product Information Publication, F-41443, November 1967.</ref> It is soluble in water to 6–10 parts per 100 parts, but it also reacts with water (see ] below).
			It has a refractive index of 1.363 with a wavelength of 589&nbsp;nm at a temperature of 20&nbsp;°C <!--needs atmospheric pressure and medium (e.g. liquid, gas, solid and type of each or reference value by which this refractiveindex and wavelength is calculated --><ref>{{cite journal |last1=Kirilin |first1=Aleksei |last2=Belova |first2=Liya |last3=Pletneva |first3=Maria |title=New aspects of isocyanate synthesis with the use of O-silylurethanes |journal=Mendeleev Communications |date=January–February 2017 |volume=27 |issue=1 |pages=99–100 |doi=10.1016/j.mencom.2017.01.033}}</ref>
	==Manufacture==
	Methyl isocyanate is usually manufactured from ] and ]. These substances react at a range of temperatures, but for large scale production, it is advantageous to combine these reactants at higher temperature in the gas phase. A mixture of methyl isocyanate and two moles of ] is formed, but N-methylcarbamoyl chloride (MCC) forms as the mixture is condensed, and leaves one ] of hydrogen chloride as a gas.]
			== Manufacture ==
	The methyl isocyanate is obtained by treating the MCC with a tertiary amine (e. g.: ], ])<ref>Slocombe R. J. & Hardy E. E., ''"Process of Producing Carbamyl Chlorides"'' '''U. S. Patent''' No. 2,480,088, August 23, 1949.</ref> or by separating it by using distillation techniques.<ref>Merz W, ''"Procédé et dispositif de préparation d'isocyanates d'alkyle"'' '''French Patent''' No. 1,400,863 assigned to Farbenfabriken Bayer AG, Germany 1965.</ref>
			Methyl isocyanate is usually manufactured by the reaction of ] and ]. For large-scale production it is advantageous to combine these reactants at higher temperature in the gas phase. A mixture of methyl isocyanate and two moles of ] is formed, but N-methylcarbamoyl chloride (MCC) forms as the mixture is condensed, leaving one ] of ] as a gas.
	]		]
			The methyl isocyanate is obtained by treating the MCC with a ], such as ], or with ],<ref>{{cite patent |country=US |number=2480088 |status=patent |inventor=Slocombe, R. J.; Hardy, E. E. |title=Process of Producing Carbamyl Chlorides |gdate=1949-08-23 |assign1=Monsanto}}</ref> or by separating it by using ] techniques.<ref>{{cite patent |country=FR |number=1400863 |status=patent |inventor=Merz, W. |title=Procédé et dispositif de préparation d'isocyanates d'alkyle |assign1=Bayer |gdate=1965-05-28}}</ref>
			]
	Methyl isocyanate is also manufactured from N-methylformamide and air. In the latter process, it is immediately consumed in a closed-loop process to make methomyl.<ref>'''Chemical Week''', ''"A fleeting existence for toxic-gas molecules"'' p. 9, June 12, 1985.</ref> Other manufacturing methods have been reported.<ref>Giesselmann G., Guenther K., Fuenten W., ''"Methyl Isocyanate"'', '''German Patent''' No. 2,828,259, January 10, 1980 (cited in '''Chemical Abstracts''' 92: 214882n).</ref><ref>'''Chemical Week''', ''"A safer method for making carbamates"'' p. 136, no. 20, 1985b.</ref>
			Methyl isocyanate is also manufactured from ] and air. In the latter process, it is immediately consumed in a closed-loop process to make ].<ref>Chemical Week, ''"A fleeting existence for toxic-gas molecules"'' p. 9, 12 June 1985.</ref> Other manufacturing methods have been reported.<ref>{{cite patent |country=DE |number=2828259 |status=patent |inventor=Giesselmann, G.; Guenther, K.; Fuenten, W. |title=Verfahren zur Herstellung von Methyl Isocyanate |gdate=1980-01-10 |assign1=Degussa}}</ref><ref>{{cite journal |journal=Chemical Week |year=1985 |title=A safer method for making carbamates |page=136 |volume=1985b |issue=20}}</ref>
	==Reactions==		== Reactions ==
			Methyl isocyanate reacts readily with many substances that contain N-H or O-H groups. With water, it forms ] and ] with the evolution of heat (1358.5 joules, or 325 calories, per gram of MIC): It is relatively slow to react at below 68&nbsp;°F, but will increase its rate with elevated temperatures or in the presence of acid or base.<ref>{{cite journal |last1=Manilla |title=Methyl isocyanate: Risk assessment, environmental, and health hazard |journal=Hazardous Gases Risk Assessment on the Environment and Human Health |date=2021 |pages=251–261}}</ref>
	Methyl isocyanate reacts readily with many substances that contain N-H or O-H groups and some other compounds. It also reacts with itself to form a trimer or higher molecular weight polymers.
			]
	Methyl isocyanate reacts with water to form ] and ] with the evolution of heat (325 calories per gram of MIC that reacts).
			At 25&nbsp;°C, in excess water, half of the MIC is consumed in 9 min.;<ref>{{cite journal |vauthors=Castro EA, Moodie RB, Sansom PJ |title=The kinetics of hydrolysis of methyl and phenyl isocyanates |journal=Journal of the Chemical Society, Perkin Transactions 2 |year=1985 |volume=1985 |issue=5 |pages=737–742 |doi=10.1039/P29850000737}}</ref> if the heat is not efficiently removed from the reacting mixture, the rate of the reaction will increase and rapidly cause the MIC to boil. Such a reaction triggered the ] after a large amount of water was introduced to a MIC storage tank. The consequence of the out of control ] was a ] and the direct release of 42 tons of MIC to the atmosphere.
	]
			If MIC is in excess, ] is formed along with ].<ref name="Union Carbide 1967" /> ] and ], which contain an O-H group, react slowly with MIC, but the reaction can be catalyzed by trialkylamines or dialkyltin dicarboxylate. ]s, ]s, and ]s also react with MIC to form methylcarbamates.<ref name="Union Carbide 1967" /> These reactions produce the products described below (]).
	At 25°C, in excess water, one-half of the MIC is consumed in 9 minutes;<ref>{{cite journal |title=The kinetics of hydrolysis of methyl and phenyl lsocyanates |author=Enrique A. Castro, Roy B. Moodie and Peter J. Sansom |journal=J. Chem. Soc., Perkin Trans. 2 |year=1985 |volume=1985 |pages=737 |doi=10.1039/P29850000737 |issue=5}}</ref> if the heat is not efficiently removed from the mixture, the rate of the reaction will increase and rapidly cause the MIC to boil. If MIC is in excess, ] is formed along with ].<ref name="Union Carbide 1967" />
			]
	Compounds that contain hydrogen attached to nitrogen, such as ] or primary or secondary ]s, will rapidly react with MIC to form substituted ]s. Other N-H compounds, such as ]s and ]s, react much more slowly with MIC.<ref>{{cite book |author=March J. |title=Advanced Organic Chemistry |edition=3rd |publisher=John Wiley & Sons |location=New York |year=1985 |pages=802}}</ref>
			], primary, and secondary ]s rapidly react with MIC to form substituted ]s. Other N-H compounds, such as amides and ]s, react much more slowly with MIC.<ref>{{cite book |vauthors=March J |title=Advanced Organic Chemistry |edition=3rd |publisher=John Wiley & Sons |location=New York |year=1985 |page=802}}</ref>
			It also reacts with itself to form a trimer or higher-molecular-weight polymers. In the presence of ], MIC reacts with itself to form a solid trimer, trimethyl isocyanurate, or a higher-molecular-weight polymer:
	] and ], which contain an O-H group, react slowly with MIC, but the reaction can be catalyzed by trialkyl]s or dialkyltin dicarboxylate.
	]		]
			], ], ] and certain other metal compounds catalyze the formation of the MIC-trimer, while the high-molecular-weight polymer formation is catalyzed by certain trialkylamines. Since the formation of the MIC trimer is ] (1246 joules, or 298 calories, per gram of MIC), the reaction can lead to violent boiling of the MIC. The high-molecular-weight polymer hydrolyzes in hot water to form the trimethyl ]. Since ] metal salts can be formed from impurities in commercial grade MIC and steel, this product must not be stored in steel drums or tanks.<ref name="Union Carbide 1967" />
			== Toxicity ==
	]s, ]s, and ]s also react with MIC to form methylcarbamates.<ref name="Union Carbide 1967" /> These reactions produce the products described below (Uses).
			Methyl isocyanate is extremely ]. There is no known ]. The threshold limit value set by the American Conference of Governmental Industrial Hygienists is 0.02 ]. MIC is toxic by inhalation, ingestion and contact in quantities as low as 0.4 ]. Exposure symptoms include coughing, ] pain, ], ], irritation of the ]s, ] and ], as well as ] damage. Higher levels of exposure, over 21 ppm, can result in pulmonary or lung ], ] and ]s, bronchial ] and ]. Although the odor of methyl isocyanate cannot be detected at 5 ppm by most people, its potent ] properties provide an excellent warning of its presence (at a concentration of 2–4 parts per million (ppm) subjected to eyes are irritated, while at 21 ppm, subjects could not tolerate the presence of methyl isocyanate in air).<ref name=Kimmerle>{{cite journal |vauthors=Kimmerle G, Eben A |title=Zur Toxizität von Methylisocyanat und dessen quantitativer Bestimmung in der Luft |journal=Archiv für Toxikologie |year=1964 |volume=20 |issue=4 |pages=235–241 |s2cid=21422558 |doi=10.1007/bf00577897|bibcode=1964ArTox..20..235K }}</ref> The irritant effects of methyl isocyanate are mediated by the irritant and tear gas receptor ] in pain-sensing nerve endings in the eye.<ref>{{Cite journal |last1=Bessac |first1=Bret F. |last2=Sivula |first2=Michael |last3=Hehn |first3=Christian A. |last4=Caceres |first4=Ana I. |last5=Escalera |first5=Jasmine |last6=Jordt |first6=Sven-Eric |date=2009-04-01 |title=Transient receptor potential ankyrin 1 antagonists block the noxious effects of toxic industrial isocyanates and tear gases |journal=The FASEB Journal |language=en |volume=23 |issue=4 |pages=1102–1114 |doi=10.1096/fj.08-117812 |doi-access=free |issn=0892-6638 |pmc=2660642 |pmid=19036859}}</ref>
			Proper care must be taken to store methyl isocyanate because of its ease of exothermically polymerizing (see ]) and its similar sensitivity to water. Only ] or ] containers may be safely used; the MIC must be stored at temperatures below {{convert|40|°C}} and preferably at {{convert|4|°C}}.{{Citation needed|date=August 2018}}
	When treated with ], MIC reacts with itself to form a solid trimer, trimethyl isocyanurate, or a higher molecular weight polymer.
			The toxic effect of the compound was apparent in the 1984 ], when around {{convert|42000|kg}} of methyl isocyanate and other gases were released from the underground reservoirs of the ] (UCIL) factory, over a populated area on 3 December 1984, killing about 3,500 people immediately, 8,000 people in the first 48 hours and 15,000 more over the next several years. 200,000 people had lasting health effects from the disaster.<ref>{{cite journal |last1=Varma |first1=Daya |last2=Mulay |first2=Shree |title=Methyl Isocyanate: The Bhopal Gas |journal=Handbook of Toxicology of Chemical Warfare Agents |date=2015 |pages=287–299 |doi=10.1016/B978-0-12-800159-2.00022-1}}</ref><ref name="convictions">{{cite news |url=http://news.bbc.co.uk/1/hi/world/south_asia/8725140.stm |title=Bhopal trial: Eight convicted over India gas disaster |date=7 June 2010 |publisher=] |access-date=7 June 2010 | archive-url=https://web.archive.org/web/20100607185745/http://news.bbc.co.uk/1/hi/world/south_asia/8725140.stm |archive-date=7 June 2010 |url-status=live}}</ref>
	]
			During structural fires, natural materials can contribute to releasing isocyanates including methyl isocyanate.<ref>Dzhordzhio Naldzhiev, Matija Strlic; Polyurethane insulation and household products – a systematic review of their impact on indoor environmental quality, , 2020</ref>
	], ], ], and certain other metal compounds catalyze the formation of the MIC-trimer, while the high-molecular-weight polymer formation is catalyzed by certain trialkyl]s. Since the formation of the MIC trimer is ] (298 calories per gram of MIC), the reaction can lead to violent boiling of the MIC. The high-molecular-weight polymer hydrolyzes in hot water to form the trimethyl isocyanurate. Since catalytic metal salts can be formed from impurities in commercial grade MIC and steel, this product must not be stored in steel drums or tanks.<ref name="Union Carbide 1967" />
			=== Mechanism of action ===
	==Uses==
			Until recent decades, the mechanism of methyl isocyanate toxicity in humans was largely unknown or unclear.<ref>{{cite journal |vauthors=Mehta PS, Mehta AS, Mehta SJ, Makhijani AB |title=Bhopal tragedy's health effects. A review of methyl isocyanate toxicity |journal=JAMA |volume=264 |issue=21 |pages=2781–2787 |date=December 1990 |pmid=2232065 |doi=10.1001/jama.1990.03450210081037}}</ref><ref>{{cite journal |vauthors=Varma DR |title=Epidemiological and experimental studies on the effects of methyl isocyanate on the course of pregnancy |journal=Environmental Health Perspectives |volume=72 |pages=153–157 |date=June 1987 |pmid=3622430 |pmc=1474644 |doi=10.1289/ehp.8772153}}</ref> Methyl isocyanate and other ]s are ]s and are currently thought to cause toxicity by the ] of biomolecules.<ref>{{cite journal |last1=Bessac |first1=B.F. |last2=Jordt |first2=S.-E. |date=2010-07-01 |title=Sensory Detection and Responses to Toxic Gases: Mechanisms, Health Effects, and Countermeasures |journal=Proceedings of the American Thoracic Society |volume=7 |issue=4 |pages=269–277 |pmid=20601631 |pmc=3136963 |issn=1546-3222 |doi=10.1513/pats.201001-004sm}}</ref> The mechanism of methyl isocyanate was previously suspected to be the ] of ], thus interfering with its oxygen-binding capability and causing ]. However, experiments showed that when ]s and ]s were exposed to methyl isocyanate at ]s above the ] (], the concentration sufficient to kill 50% of the tested population), only 2% of hemoglobin molecules were carbamylated, suggesting that this is probably not the mechanism of toxicity.<ref>{{cite journal |last1=Varma |first1=Daya R.|last2=Guest |first2=Ian |date=1993 |title=The Bhopal accident and methyl isocyanate toxicity |journal=Journal of Toxicology and Environmental Health |volume=40 |issue=4 |pages=513–529 |pmid=8277516 |bibcode=1993JTEH...40..513V |issn=0098-4108 |doi=10.1080/15287399309531816}}</ref><ref>{{cite journal |last1=Ramachandran |first1=P.K. |last2=Gandhe |first2=B.R. |last3=Venkateswaran |first3=K.S. |last4=Kaushik |first4=M.P. |last5=Vijayaraghavan |first5=R. |last6=Agarwal |first6=G.S. |last7=Gopalan |first7=N. |last8=Suryanarayana |first8=M.V.S. |last9=Shinde |first9=S.K. |last10=Sriramachari |first10=S. |date=1988 |title=Gas chromatographic studies of the carbamylation of haemoglobin by methyl isocyanate in rats and rabbits |journal=Journal of Chromatography B: Biomedical Sciences and Applications |volume=426 |issue=2 |pages=239–247 |pmid=3392138 |issn=0378-4347 |doi=10.1016/s0378-4347(00)81952-0}}</ref>
	Methyl isocyanate is an intermediate chemical in the production of ] ]s (such as ], ], ], and ]). It has also been used in the production of ]s and ]s.
			== Extraterrestrial occurrence ==
	==Hazards==
			] ] (northern ]).<ref name="ALMA" />]]
	Methyl isocyanate (MIC) is extremely ]. The threshold limit value set by the American Conference on Government Industrial Hygienist was 0.02 ]. MIC can damage by inhalation, ingestion and contact in quantities as low as 0.4 ]. Damage includes coughing, ] pain, ], ], irritation of the ]s, ] and ], as well as ] damage. Higher levels of exposure, over 21 ppm, can result in pulmonary or lung ], ] and ]s, bronchial ] and ]. Although the odor of methyl isocyanate cannot be detected at 5 ppm by most people, its potent ] properties provide an excellent warning of its presence (at a concentration of 2–4 parts per million (ppm) subject's eyes are irritated, while at 21 ppm, subjects could not tolerate the presence of methyl isocyanate in air).<ref>Kimmerle G, and Eben A., ''"Zur Toxicität von Methylisocyanat und dessen quantitativer Bestimmung in der Luft"'', '''Achiv fur Toxikologie''', no. 20, 235–241, 1964.</ref>
			On 30 July 2015, scientists reported that upon the first touchdown of the '']'' lander on ] ]{{'s}} surface, measurements by the ] revealed sixteen ]s, four of which were seen for the first time on a ], including ], ], methyl isocyanate and ].<ref name="wapo20150730">{{cite news |url=https://www.washingtonpost.com/world/philae-probe-finds-evidence-that-comets-can-be-cosmic-labs/2015/07/30/63a2fc0e-36e5-11e5-ab7b-6416d97c73c2_story.html |archive-url=https://web.archive.org/web/20181223235109/https://www.washingtonpost.com/world/philae-probe-finds-evidence-that-comets-can-be-cosmic-labs/2015/07/30/63a2fc0e-36e5-11e5-ab7b-6416d97c73c2_story.html |url-status=dead |archive-date=23 December 2018 |title=Philae probe finds evidence that comets can be cosmic labs |newspaper=The Washington Post |agency=Associated Press |vauthors=Jordans F |date=30 July 2015 |access-date=30 July 2015}}</ref><ref name="esa20150730">{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Rosetta/Science_on_the_surface_of_a_comet |title=Science on the Surface of a Comet |publisher=European Space Agency |date=30 July 2015 |access-date=30 July 2015 |url-status=live |archive-url=https://web.archive.org/web/20150802005802/http://www.esa.int/Our_Activities/Space_Science/Rosetta/Science_on_the_surface_of_a_comet |archive-date=2 August 2015}}</ref><ref name="SCI-20150731">{{cite journal |vauthors=Bibring JP, Taylor MG, Alexander C, Auster U, Biele J, Finzi AE, Goesmann F, Klingelhoefer G, Kofman W, Mottola S, Seidensticker KJ, Spohn T, Wright I |display-authors=6 |title=Philae's first look. Philae's First Days on the Comet. Introduction |journal=Science |volume=349 |issue=6247 |pages=493 |date=July 2015 |pmid=26228139 |bibcode=2015Sci...349..493B |doi=10.1126/science.aac5116 |doi-access=free|url=https://elib.dlr.de/97953/1/Science-2015-Bibring-493.pdf }}</ref>
			In 2017, two teams of astronomers using the ] (ALMA) ] made of 66 radio telescopes in the ] (northern ]) have discovered the presence of MIC around young Sun-like stars.<ref name="ALMA">{{cite web |title=ALMA Finds Ingredient of Life Around Infant Sun-like Stars |url=https://www.eso.org/public/news/eso1718/ |website=www.eso.org |access-date=8 June 2017 |url-status=live |archive-url=https://web.archive.org/web/20170608143057/http://www.eso.org/public/news/eso1718/ |archive-date=8 June 2017}}</ref>
	Proper care must be taken to store methyl isocyanate because of its ease of exothermically polymerizing (see Reactions) and its similar sensitivity to water. Only stainless steel or glass containers may be safely used; the MIC must be stored at temperatures below {{convert|40|°C}} and preferably at {{convert|4|°C}}.
			MIC is considered a ] as explained by the discoverers of the ALMA findings in ], a multiple system of very young stars: "This family of organic molecules is involved in the synthesis of ]s and ]s, which, in the form of ]s, are the biological basis for life as we know it".<ref name="ALMA" />
	The toxic effect of the compound was apparent in the ], when around {{convert|42000|kg}} of methyl isocyanate and other gases were released from the underground reservoirs of ] (UCIL) factory, over a populated area on December 3, 1984, immediately killing thousands and leading to the deaths of tens of thousands in subsequent weeks and months.
	==References==		== References ==
			{{reflist}}
	<references />
	==External links==		== External links ==
	* , from the website of the National Institute for Occupational Safety and Health (NIOSH)		* , from the website of the National Institute for Occupational Safety and Health (NIOSH).
	*		*
			{{Chemical agents}}
			{{Authority control}}
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