Methyl nitrite is an organic compound with the chemical formula . It is a gas, and is the simplest alkyl nitrites.
Structure
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.
The cis and trans structure have also been determined by microwave spectroscopy (see external links).
Synthesis
Methyl nitrite can be prepared by the reaction of
silver nitrite with
iodomethane: Silver nitrite (AgNO
2) exists in solution as the silver
ion, Ag
+ and the nitrite ion, NO
2−. One of the
on an oxygen from nitrite ion attacks the methyl group (−CH
3), releasing the
iodide ion into solution.
Unlike silver nitrite, silver iodide is highly insoluble in water and thus forms a solid.
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 nitrite 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.
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:
Properties and uses
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.
Environmental impact
As one product of the combustion of
unleaded petrol in air, methyl nitrite has been proposed as a cause of the decline of
, and hence that of
in
Europe.
Safety
Methyl nitrite is a toxic asphyxiating gas, a potent
cyanosis agent. Exposure may result in methemoglobinemia.
[ 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.[ 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.
See also
Cited sources
External links
