methyl nitrite

At room temperature, methyl nitrite exists as a mixture of cis and trans conformers. The cis conformer is 3.13 kJ mol⁻¹, more stable than the trans form, with an energy barrier to rotation of 45.3 kJ mol⁻¹.{{cite journal | journal = Journal of Physical Chemistry | year = 1990 | volume = 94 | issue = 10 | pages = 4029–39 | title=Infrared spectrum, ab initio calculations, barriers to internal rotation and structural parameters for methyl nitrite | doi = 10.1021/j100373a028 | last1 = Van Der Veken | first1 = B. J. | last2 = Maas | first2 = R. | last3 = Guirgis | first3 = G. A. | last4 = Stidham | first4 = H. D. | last5 = Sheehan | first5 = T. G. | last6 = Durig | first6 = James R. }} The cis and trans structure have also been determined by microwave spectroscopy (see external links).

Methyl nitrite can be prepared by the reaction of silver nitrite with iodomethane: Silver nitrite (AgNO₂) exists in solution as the silver ion, Ag⁺ and the nitrite ion, NO₂⁻. One of the lone pairs on an oxygen from nitrite ion attacks the methyl group (−CH₃), releasing the iodide ion into solution.{{cite book |author1=Pavia, Donald L. |author2=Lampman, Gary M. |author3=Kriz, George S. |year=2004 |title=Organic Chemistry |volume=2 |location=Mason, Ohio |publisher=Thompson Custom Publishing |oclc=236055357 |isbn=978-0-03-014813-2}} Unlike silver nitrite, silver iodide is highly insoluble in water and thus forms a solid.{{cite book |author1=Darrell D. Ebbing |author2=Steven D. Gammon |year=2005 |title=General Chemistry |url=https://archive.org/details/generalchemistr000darr |url-access=registration |edition=8th |location=Boston |publisher=Houghton Mifflin |isbn=978-0-618-39941-3}} Note that nitrogen is a better nucleophile than oxygen and most nitrites would react via an S_N2-like mechanism and the major product would be nitromethane. For example, sodium and potassium nitrite reacting with iodomethane would produce mostly nitromethane, with methyl nitrite as the minor product. However, the presence of the silver ion in solution has a stabilizing effect on the formation of carbocation intermediates, increasing the percent yield of methyl nitrite. In either case, some nitromethane and methyl nitrite are both formed.

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The figure shows the two gas-phase structures of methyl nitrite, as determined by IR and microwave spectroscopy.

Methyl nitrite free of nitromethane can be made by reacting iodomethane with nitrogen dioxide:

:{{chem2 | 2 CH3I + 2 NO2 -> 2 CH3ONO + I2 }}

Methyl nitrite is a precursor and intermediate, e.g. during production of phenylpropanolamine.

Methyl nitrite is also present in aged cigarette smoke. Here it is presumably formed from nitrogen dioxide (itself formed by oxidation of nitric oxide) and methanol.{{Cite book | url=https://books.google.com/books?id=D2HvBQAAQBAJ&q=methyl+nitrite&pg=PA827 | title=The Chemical Components of Tobacco and Tobacco Smoke| isbn=9781466515529| last1=Rodgman| first1=Alan| last2=Perfetti| first2=Thomas A.| date=2016-04-19| publisher=CRC Press}}

As one product of the combustion of unleaded petrol in air, methyl nitrite has been proposed as a cause of the decline of insects, and hence that of songbirds in Europe.{{Cite journal|last=Summers-Smith|first=J. Denis|authorlink=J. Denis Summers-Smith|journal=British Birds|volume=100|date=September 2007|page=558|issn=0007-0335|title=Is unleaded petrol a factor in urban House Sparrow decline?}}

Methyl nitrite is a toxic asphyxiating gas, a potent cyanotic agent. Exposure may result in methemoglobinemia.[https://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@term+@DOCNO+7197 METHYL NITRITE – National Library of Medicine HSDB Database]. Toxnet.nlm.nih.gov. Retrieved on 2019-03-10.

Methyl nitrite is an oxidizing agent and a heat-sensitive explosive; its sensitivity increases in presence of metal oxides. With inorganic bases it forms explosive salts. It forms explosive mixtures with air. It is used as a rocket propellant, a monopropellant.[https://cameochemicals.noaa.gov/chemical/3953 Methyl Nitrite]. Cameochemicals.noaa.gov. Retrieved on 2019-03-10. It explodes more violently than ethyl nitrite. Lower alkyl nitrites may decompose and burst the container even when stored under refrigeration.{{Cite book | url=https://books.google.com/books?id=4_PJCgAAQBAJ&q=methyl+nitrite&pg=PA1501 | title=Bretherick's Handbook of Reactive Chemical Hazards| isbn=9781483162508| last1=Bretherick| first1=L.| date=2016-10-27| publisher=Elsevier}}

• Nitromethane
• Organic chemistry
• Nucleophilic substitution

{{Reflist}}

• {{cite book | editor= Haynes, William M. | year = 2011 | title = CRC Handbook of Chemistry and Physics | edition = 92nd | publisher = CRC Press | isbn = 978-1439855119| title-link = CRC Handbook of Chemistry and Physics }}

{{Commonscat}}

• [http://webbook.nist.gov/cgi/cbook.cgi?ID=C624919 WebBook page for CH3NO2]
• [http://pubs.acs.org/doi/abs/10.1021/j100474a023 Determination of cis and trans structures of methyl nitrite by microwave spectroscopy.]

{{Nitric oxide signaling}}

Category:Antianginals

Category:Antidotes

Category:Methyl esters

Category:Alkyl nitrites

Category:Explosive gases

Category:Explosive chemicals