Methyl isocyanide
IUPAC name
Other names
  • Methyl isocyanide
  • Isoacetonitrile
  • Methylisonitrile
  • Isomethanenitrile
  • Methaneisonitrile
3D model (JSmol)
ECHA InfoCard 100.008.917 Edit this at Wikidata
EC Number
  • 209-806-9
  • InChI=1S/C2H3N/c1-3-2/h1H3 checkY
  • InChI=1/C2H3N/c1-3-2/h1H3
  • [C-]#[N+]C
Molar mass 41.053 g·mol−1
Appearance Colorless liquid
Density 0.69 g/mL
Melting point −45 °C (−49 °F; 228 K)
Boiling point 59 to 60 °C (138 to 140 °F; 332 to 333 K)
GHS labelling:
GHS07: Exclamation markGHS08: Health hazard
H302, H312, H332, H373
P260, P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P312, P304+P340, P312, P314, P322, P330, P363, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
Related compounds
Related compounds
acetic acid, acetamide, ethylamine, Acetonitrile
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Methyl isocyanide or isocyanomethane is an organic compound and a member of the isocyanide family. This colorless liquid is isomeric and isoelectronic to methyl cyanide (acetonitrile), 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 rings. The C-N distance in methyl isocyanide is very short, 1.158 Å as is characteristic of isocyanides. [1]

Preparation and uses

Methyl isocyanide was first prepared by A. Gautier by reaction of silver cyanide with methyl iodide.[2][3] The common method for preparing methyl isocyanides is the dehydration of N-methylformamide.[4] Many metal cyanides react with methylating agents to give complexes of methyl isocyanide.[5] This kind of reactivity has been invoked as being relevant to the origin of life.[6]

Methyl isocyanide is useful for the preparation of diverse heterocycles. It is often used to prepare transition metal isocyanide complexes.[7]


Methyl isocyanide is very endothermic (ΔfH(g) = +150.2 kJ/mol, 3.66 kJ/g) and can isomerize explosively to acetonitrile.[8] 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.[9]


  1. ^ Kessler, Myer; Ring, Harold; Trambarulo, Ralph; Gordy, Walter (1950-07-01). "Microwave Spectra and Molecular Structures of Methyl Cyanide and Methyl Isocyanide". Physical Review. American Physical Society (APS). 79 (1): 54–56. Bibcode:1950PhRv...79...54K. doi:10.1103/physrev.79.54. ISSN 0031-899X.
  2. ^ Gautier, A. (1868). "Ueber eine neue Reihe von Verbindungen, welche mit den Cyanwasserstoffsäure-Aethern isomer sind". Justus Liebigs Annalen der Chemie. 146 (1): 119–124. doi:10.1002/jlac.18681460107.
  3. ^ Gautier, A. (1869). "Des Nitriles des Acides Gras: Deuxième Partie - Des Carbylamines". Annales de Chimie et de Physique. 17: 203.
  4. ^ R. E. Schuster, James E. Scott, and Joseph Casanova, Jr (1966). "Methyl isocyanide". Organic Syntheses. 46: 75. doi:10.15227/orgsyn.046.0075.((cite journal)): CS1 maint: multiple names: authors list (link)
  5. ^ Fehlhammer, Wolf P.; Fritz, Marcus. (1993). "Emergence of a CNH and Cyano Complex Based Organometallic Chemistry". Chemical Reviews. 93 (3): 1243–1280. doi:10.1021/cr00019a016.
  6. ^ Mariani, Angelica; Russell, David; Javelle, Thomas; Sutherland, John (2018). "A Light-Releasable Potentially Prebiotic Nucleotide Activating Agent". Journal of the American Chemical Society. 140 (28): 8657–8661. doi:10.1021/jacs.8b05189. PMC 6152610. PMID 29965757.
  7. ^ Eckert, H.; Nestl, A.; Ugi, I. (2001). "Methyl Isocyanide". Encyclopedia of Reagents for Organic Synthesis. John Wiley & Sons. doi:10.1002/047084289X.rm198. ISBN 0471936235.
  8. ^ Clothier, P. Q. E.; Glionna, M. T. J.; Pritchard, H. O. (July 1985). "Thermal explosions of methyl isocyanide in spherical vessels". The Journal of Physical Chemistry. 89 (14): 2992–2996. doi:10.1021/j100260a008. ISSN 0022-3654.
  9. ^ Urben, Peter (22 May 2017). Bretherick's Handbook of Reactive Chemical Hazards | ScienceDirect. ISBN 9780081009710. Retrieved 2022-02-23.