Methyl isocyanate's structure

3D model of the MIC molecule

Methyl isocyanate (MIC) is an organic compound with the molecular formula C₂H₃NO, arranged as H₃C-N=C=O. Synonyms are isocyanatomethane, methyl carbylamine, and MIC. It was discovered in 1888 as an ester of isocyanic acid. The best known incident involving methyl isocyanate is the Bhopal disaster. Image File history File links Download high resolution version (1100x493, 13 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Methyl isocyanate ... Image File history File links Download high resolution version (1100x493, 13 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Methyl isocyanate ... Image File history File links Download high resolution version (1100x710, 150 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Methyl isocyanate ... Image File history File links Download high resolution version (1100x710, 150 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Methyl isocyanate ... General formula of a carboxylate ester. ... Cyanic acid is a colourless poisonous liquid with a boiling point of 23. ... Time cover about Bhopal disaster. ...

Physical properties

Methyl isocyanate is a clear, colorless, lachrymatory, sharp smelling liquid. It is highly flammable, boils at 39.1°C and has a low flash point (Union Carbide, 1967). Methyl isocyanate is soluble in water to 6-10 parts per 100 parts, but it reacts with the water (see Reactions). Categories: Stub | Chemical weapons ... The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture with air. ...

Manufacture

Methyl isocyanate is usually manufactured from monomethylamine and phosgene. 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 hydrogen chloride is formed, but N-methylcarbamoyl chloride (MCC) forms as the mixture is condensed and leaves one mole of hydrogen chloride as a gas. Flash point  ? °C R/S statement R: ? S: ? RTECS number PF6300000 Supplementary data page Structure and properties n, εr, etc. ... Phosgene (also known as carbonyl chloride, COCl2) is a highly toxic gas or refrigerated liquid that was used as a chemical weapon in World War I. It has no color, but is detectable in air by its odor, which resembles moldy hay. ... R-phrases , S-phrases , , , , Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ... The mole and its simple conversions into different units of measurements. ...

The methyl isocyanate is obtained by treating the MCC with a tertiary amine (e. g.: dimethylaniline, pyridine(Slocombe & Hardy 1949) or by separating it by using distillation techniques (Merz 1965). Image File history File links MMA_plus_Phosgene_diagram. ... Dimethylaniline is a chemical compound consisting of a ring of six carbon atoms, with three double bonds each equally spaced with a single bond between them. ... Pyridine is a clear liquid with an odor that is sour, putrid, and fish-like. ...

Methyl isocyanate is also manufactured from N-methyformamide and air. In the latter process it is immediately consumed in a closed-loop process to make methomyl (Chem.Week 1985a). Other manufacturing methods have been reported (Giesselmann et al. 1980; Chem. Week 1985b). Image File history File links MCC_to_MIC_&_HCl. ...

Reactions

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 1,3-dimethylurea and carbon dioxide with the evolution of heat (325 calories per gram of MIC that reacts). Urea is an organic compound of carbon, nitrogen, oxygen and hydrogen, with the formula CON2H4 or (NH2)2CO. Urea is also known as carbamide, especially in the recommended International Non-proprietary Names (rINN) in use in Europe. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ...

At 25°C, in excess water, one-half of the MIC is consumed in 9 minutes (Castro et al. 1985); 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, 1,3,5-trimethylbiuret is formed along with carbon dioxide (Union Carbide 1967). Image File history File links MIC_&_water_to_DMU_&_TMB.png Summary Reaction of methyl isocyanate with water drawn by Oldsci with ISIS-draw Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Methyl isocyanate ... Biuret is a chemical compound with the chemical formula C2O2N3H5. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ...

Compounds that contain hydrogen attached to nitrogen, such as ammonia or primary or secondary amines, will rapidly react with MIC to form substituted ureas. Other N-H compounds, such as amides and ureas, react much more slowly with MIC (March 1985). Ammonia is a compound of nitrogen and hydrogen with the formula NH3. ... Ammonia Amines are organic compounds containing nitrogen as the key atom in the amine functional group. ... Urea is an organic compound of carbon, nitrogen, oxygen and hydrogen, with the formula CON2H4 or (NH2)2CO. Urea is also known as carbamide, especially in the recommended International Non-proprietary Names (rINN) in use in Europe. ... In chemistry, the term amide has several meanings. ... Urea is an organic compound of carbon, nitrogen, oxygen and hydrogen, with the formula CON2H4 or (NH2)2CO. Urea is also known as carbamide, especially in the recommended International Non-proprietary Names (rINN) in use in Europe. ...

Alcohols and phenols, which contain an O-H group, react slowly with MIC, but the reaction can be catalyzed by trialkylamines or dialkyltin dicarboxylate. In general usage, alcohol (from Arabic al-khwl الكحول, or al-ghawl الغول) refers almost always to ethanol, also known as grain alcohol, and often to any beverage that contains ethanol (see alcoholic beverage). ... In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of a hydroxyl group (-OH) attached to an aromatic hydrocarbon group. ... Ammonia Amines are organic compounds containing nitrogen as the key atom in the amine functional group. ...

Oximes, hydroxylamines, and enols also react with MIC to form methylcarbamates (Union Carbide 1967). These reactions produce the products described below (Uses). When treated with catalysts, MIC reacts with itself to form a solid trimer, trimethyl isocyanurate, or a higher molecular weight polymer. Image File history File links MIC_plus_1-naphthol_to_carbaryl. ... An oxime is one in a class of chemical compounds with the general formula R1R2 C N O H, where R1 is an organic side chain and R2 is either hydrogen, forming an aldoxime, or another organic group, forming a ketoxime. ... The compound hydroxylamine is a nitrogen-containing base whose chemical formula is NH2OH, and is therefore a close relative of the compound ammonia. ... Enol (or, more officially, but less commonly: alkenol) is an alkene with hydroxyl group on one of the carbon atoms of the double bond. ... A catalyst (Greek: καταλύτης) is a substance that accelerates the rate of a chemical reaction, at some temperature, but without itself being transformed or consumed by the reaction (see also catalysis). ...

Sodium methoxide, triethyl phosphine, ferric chloride, and certain other metal compounds catalyze the formation of the MIC-trimer, while the higher molecular weight polymer formation is catalyzed by certain trialkylamines. Since the formation of the MIC trimer is exothermic (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 (Union Carbide 1967). Image File history File links MIC_to_trimer. ... An alkoxide has an organic group bonded to a negatively charged oxygen atom, they are generally basic. ... R-phrases , , , , S-phrases , , , , , Flash point flammable gas Autoignition temperature 38 °C (see text) Explosive limits 1. ... Ferric chloride (FeCl3) is an iron-based salt. ... Ammonia Amines are organic compounds containing nitrogen as the key atom in the amine functional group. ... Exothermic means to release energy in the form of heat. ...

Uses

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. Carbamates are a group of organic compounds sharing a common functional group with the general structure -NH(CO)O-. More precisely the carbamate group is considered an amide group with an alkoxy or hydroxy functional group next to the carbonyl group. ... A cropduster spreading pesticide. ... Carbaryl is a chemical in the carbamate family used chiefly as an insecticide. ... Carbofuran is the most toxic of the carbamate pesticides. ... This subtance is a carbamate with strucural formula: 2-methyl-2-(methylthio)propionaldehyde O-methylcarbamoyloxime. ... Rubber is an elastic hydrocarbon polymer which occurs as a milky emulsion (known as latex) in the sap of several varieties of plants though can be produced synthetically. ... An adhesive is a compound that adheres or bonds two items together. ...

Hazards

Methyl isocyanate is extremely toxic and can damage by inhalation, ingestion and contact in quantities as low as 0.4 ppm. Damage includes coughing, chest pain, dyspnea, asthma, irritation of the eyes, nose and throat as well as skin damage. Higher levels of exposure, over 21 ppm, can result in pulmonary or lung edema, emphysema and hemorrhages, bronchial pneumonia and death. Although the detectable odor of methyl isocyanate is a concentration triple the permissible exposure, its potent lachrymal 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)(Kimmerle and Eben 1964). Toxic redirects here, but this is also the name of a song by Britney Spears; see Toxic (song) Look up toxic and toxicity in Wiktionary, the free dictionary. ... Parts per million (ppm) is a measure of concentration that is used where low levels of concentration are significant. ... Chest of a human male The chest is a part of the anatomy of humans and various other animals. ... Dyspnea (Latin dyspnoea, Greek dyspnoia from dyspnoos, short of breath) or shortness of breath (SOB) is perceived difficulty breathing or pain on breathing. ... Closeup of a blue-green human eye. ... Human nose in profile You may be looking for Nose, a town in Japan, or The Nose, a story by Nikolai Gogol and an opera by Dmitri Shostakovich. ... Anatomy In anatomy, the throat is the part of the neck anterior to the vertebral column. ... A close-up of human skin. ... Edema (BE: oedema, formerly known as dropsy) is swelling of any organ or tissue due to accumulation of excess fluid. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Pneumonia is an illness of the lungs and respiratory system in which the microscopic, alveoli (air-filled sacs) responsible for absorbing oxygen from the atmosphere become inflamed and flooded with fluid. ... Categories: Stub | Chemical weapons ...

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 40ºC.

The toxic effect of the compound was apparent in the Bhopal accident, when around 40,000 kilograms of methyl isocyanate were released over a populated area on December 3, 1984, killing thousands of people. Time cover about Bhopal disaster. ... The international prototype, made of platinum-iridium, which is kept at the BIPM under conditions specified by the 1st CGPM in 1889. ... December 3 is the 337th (in leap years the 338th) day of the year in the Gregorian calendar. ... 1984 (MCMLXXXIV) was a leap year starting on Sunday of the Gregorian calendar. ...

References

Castro E. A. et al; J Chem Soc Perkin 2 5: 737-42 (1985).

Chemical Week, “A fleeting existence for toxic-gas molecules” p. 9, June 12,1985a.

Chemical Week, “A safer method for making carbamates” p. 136, no. 20, 1985b.

Giesselmann G., Guenther K., Fuenten W., “Methyl Isocyanate”, German Patent No. 2,828,259, January 10, 1980 (cited in Chemical Abstracts 92: 214882n).

Kimmerle G, and Eben A., “Zur Toxicität von Methylisocyanat und dessen quantitativer Bestimmung in der Luft”, Achiv fur Toxikologie, no. 20, 235-241, 1964.

March J. Advanced Organic Chemistry, 3rd ed., John Wiley & Sons, New York, p. 802, 1985.

Merz W, “Procédé et dispositif de préparation d’isocyanates d’alkyle” French Patent No. 1,400,863 assigned to Farbenfabriken Bayer AG, Germany 1965.

Slocombe R. J. & Hardy E. E., “Process of Producing Carbamyl Chlorides” U. S. Patent No. 2,480,088, August 23, 1949.

Union Carbide Corporation "Methyl Isocyanate” Product Information Publication, F-41443, November 1967.

External links

• NIOSH Safety and Health Topic: Isocyanates, from the website of the National Institute for Occupational Safety and Health (NIOSH)
• Methyl isocyanate from National Library of Medicine's Hazardous Substances Database