Methyl isocyanide or isocyanomethane is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

and a member of the

isocyanide An isocyanide (also called isonitrile or carbylamine) is an organic compound with the functional group –. It is the isomer of the related nitrile (–C≡N), hence the prefix is ''isocyano''.IUPAC Goldboo''isocyanides''/ref> The organic fragme ...

family. This colorless liquid is isomeric to methyl cyanide (

acetonitrile Acetonitrile, often abbreviated MeCN (methyl cyanide), is the chemical compound with the formula and structure . This colourless liquid is the simplest organic nitrile (hydrogen cyanide is a simpler nitrile, but the cyanide anion is not clas ...

), but its reactivity is very different. In contrast to the faintly sweet, ethereal odor of acetonitrile, the smell of methyl isocyanide, like that of other simple volatile isocyanides, is distinctly penetrating and vile. Methyl isocyanide is mainly used for making 5-membered

heterocyclic A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and ...

rings. The C-N distance in methyl isocyanide is very short, 1.158 Å as is characteristic of isocyanides.

Preparation and uses

Methyl isocyanide was first prepared by A. Gautier by reaction of

silver cyanide Silver cyanide is the chemical compound with the formula AgCN. It is a white solid that precipitated upon treatment of solutions containing Ag+ with cyanide, which is used in some schemes to recover silver from solution. Silver cyanide is used in ...

with

methyl iodide Iodomethane, also called methyl iodide, and commonly abbreviated "MeI", is the chemical compound with the formula CH3I. It is a dense, colorless, volatile liquid. In terms of chemical structure, it is related to methane by replacement of one h ...

. The common method for preparing methyl isocyanides is the dehydration of ''N''-methylformamide. Many metal cyanides react with methylating agents to give complexes of methyl isocyanide. This kind of reactivity has been invoked as being relevant to the origin of life. Methyl isocyanide is useful for the preparation of diverse heterocycles. It is often used to prepare

transition metal isocyanide complexes Technetium (99mTc) sestamibi is used in nuclear medicine imaging. Transition metal isocyanide complexes are coordination compounds containing isocyanide ligands. Because isocyanides are relatively basic, but also good pi-acceptors, a wide range ...

Safety

Methyl isocyanide is very endothermic (Δ_f''H''^⦵(g) = +150.2 kJ/mol, 3.66 kJ/g) and can isomerize explosively to acetonitrile. A sample exploded when heated in a sealed ampoule, and during redistillation at 59 °C/1 bar, a drop of liquid fell back into the dry boiler flask and exploded violently. The explosive decomposition of methyl isocyanide has been studied in detail.

References

External links

* {{Molecules detected in outer space Hazardous air pollutants Isocyanides Ligands Foul-smelling chemicals