Methyl isocyanide

Formula: C₂H₃N
Molecular weight: 41.0519
IUPAC Standard InChI: InChI=1S/C2H3N/c1-3-2/h1H3
IUPAC Standard InChIKey: ZRKSVHFXTRFQFL-UHFFFAOYSA-N
CAS Registry Number: 593-75-9
Chemical structure:
This structure is also available as a 2d Mol file
Other names: Methane, isocyano-; Isocyanomethane; Methyl isonitrile; CH3NC
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- Condensed phase thermochemistry data
- Phase change data
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Gas phase thermochemistry data

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Data compiled as indicated in comments:
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DRB - Donald R. Burgess, Jr.

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	39.1 ± 1.7	kcal/mol	Cm	Baghal-Vayjooee, Collister, et al., 1977	Reanalyzed by Pedley, Naylor, et al., 1986, Original value = 41.32 ± 0.24 kcal/mol; Heat of isomerization; ALS
Δ_fH°_gas	34.13	kcal/mol	N/A	Lemoult, 1906	Value computed using Δ_fH_liquid° value of 112.0 kj/mol from Lemoult, 1906 and Δ_vapH° value of 30.8 kj/mol from Baghal-Vayjooee, Collister, et al., 1977.; DRB

Reaction thermochemistry data

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Data compiled as indicated in comments:
B - John E. Bartmess
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.

Individual Reactions

C₂H₂N^- + = Methyl isocyanide

By formula: C₂H₂N^- + H⁺ = C₂H₃N

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	380.6 ± 2.1	kcal/mol	G+TS	Matimba, Crabbendam, et al., 1992	gas phase; B
Δ_rH°	374.5 ± 2.1	kcal/mol	G+TS	Filley, DePuy, et al., 1987	gas phase; Matimba, Crabbendam, et al., 1992 indicate that CN- loss interfered with equilibrium here.; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	373.1 ± 2.0	kcal/mol	IMRE	Matimba, Crabbendam, et al., 1992	gas phase; B
Δ_rG°	367.0 ± 2.0	kcal/mol	IMRE	Filley, DePuy, et al., 1987	gas phase; Matimba, Crabbendam, et al., 1992 indicate that CN- loss interfered with equilibrium here.; B

Methyl isocyanide =

By formula: C₂H₃N = C₂H₃N

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-23.70 ± 0.14	kcal/mol	Cm	Baghal-Vayjooee, Collister, et al., 1977	gas phase; Heat of isomerization; ALS

Gas phase ion energetics data

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Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias

Data compiled as indicated in comments:
B - John E. Bartmess
MM - Michael M. Meot-Ner (Mautner)
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron

View reactions leading to C₂H₃N⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	200.5	kcal/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	192.8	kcal/mol	N/A	Hunter and Lias, 1998	HL

Gas basicity at 298K

Gas basicity (review) (kcal/mol)	Reference	Comment
202.8 ± 1.3	Witt and Grutzmacher, 1997	T = 298K; Equilibrium constant measured directly. Data readjusted to 98 HUN/LIA; MM

Ionization energy determinations

IE (eV)	Method	Reference	Comment
11.53 ± 0.04	EI	Harland and McIntosh, 1985	LBLHLM
11.5 ± 0.25	EI	Chess, Lapp, et al., 1982	LBLHLM
11.24	PE	Bevan, Sandorfy, et al., 1981	LLK
11.24	PE	Lake and Thompson, 1971	LLK
11.83	EI	Heerma and deRidder, 1970	RDSH
11.27	PE	Bevan, Sandorfy, et al., 1981	Vertical value; LLK
11.32	PE	Asbrink, Von Niessen, et al., 1980	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
CH₃⁺	14.76	CN	EI	Heerma and deRidder, 1970	RDSH
C₂HN⁺	14.56 ± 0.08	?	EI	Harland and McIntosh, 1985	LBLHLM
C₂HN⁺	14.46	H₂	EI	Heerma and deRidder, 1970	RDSH
C₂H₂N⁺	13.21 ± 0.04	H	EI	Harland and McIntosh, 1985	LBLHLM
C₂H₂N⁺	13.21	H	EI	Heerma and deRidder, 1970	RDSH
C₂N⁺	18.33 ± 0.06	?	EI	Harland and McIntosh, 1985	LBLHLM
C₂N⁺	18.28	?	EI	Heerma and deRidder, 1970	RDSH

De-protonation reactions

C₂H₂N^- + = Methyl isocyanide

By formula: C₂H₂N^- + H⁺ = C₂H₃N

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	380.6 ± 2.1	kcal/mol	G+TS	Matimba, Crabbendam, et al., 1992	gas phase; B
Δ_rH°	374.5 ± 2.1	kcal/mol	G+TS	Filley, DePuy, et al., 1987	gas phase; Matimba, Crabbendam, et al., 1992 indicate that CN- loss interfered with equilibrium here.; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	373.1 ± 2.0	kcal/mol	IMRE	Matimba, Crabbendam, et al., 1992	gas phase; B
Δ_rG°	367.0 ± 2.0	kcal/mol	IMRE	Filley, DePuy, et al., 1987	gas phase; Matimba, Crabbendam, et al., 1992 indicate that CN- loss interfered with equilibrium here.; B

Mass spectrum (electron ionization)

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Data compiled by: NIST Mass Spectrometry Data Center, William E. Wallace, director

Spectrum

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Additional Data

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Owner	NIST Mass Spectrometry Data Center Collection (C) 2014 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.
Origin	R.G.GILLIS AUST SCI SERVICE, ASCOT VALE, VIC., AUSTRALIA
NIST MS number	47

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Vibrational and/or electronic energy levels

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Data compiled by: Takehiko Shimanouchi

Symmetry: C_3ν Symmetry Number σ = 3

Sym.	No	Approximate	Selected Freq.		Infrared		Raman

Species		type of mode	Value	Rating	Value	Phase	Value	Phase

a₁	1	CH3 s-str	2966	B	2965.8 M	gas	2951 S	liq.
a₁	2	NC str	2166	B	2166.0 M	gas	2161 S	liq.
a₁	3	CH3 s-deform	1429	D	1429	gas	1414 M	liq.
a₁	4	CN str	945	B	944.6 M	gas	928 M	liq.
e	5	CH3 d-str	3014	B	3014.3 S	gas	3002 W	liq.
e	6	CH3 d-deform	1467	B	1466.9 S	gas	1456 W	liq.
e	7	CH3 rock	1129	B	1129.3 S	gas
e	8	CNC bend	263	C	263 W	gas	290 S	liq.

Source: Shimanouchi, 1972

Notes

Strong

Medium

Weak

1~3 cm^-1 uncertainty

3~6 cm^-1 uncertainty

6~15 cm^-1 uncertainty

Gas Chromatography

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, Mass spectrum (electron ionization), Vibrational and/or electronic energy levels, References, Notes

Data compiled by: NIST Mass Spectrometry Data Center, William E. Wallace, director

Normal alkane RI, polar column, temperature ramp

View large format table.

Column type	Active phase	I	Reference	Comment
Capillary	DB-Wax	1010.	Duque, Bonilla, et al., 2001	30. m/0.25 mm/0.25 μm, Helium, 4. K/min, 220. C @ 30. min; T_start: 25. C

Normal alkane RI, polar column, custom temperature program

View large format table.

Column type	Active phase	I	Reference	Comment
Capillary	SOLGel-Wax	1002.	Johanningsmeier and McFeeters, 2011	30. m/0.25 mm/0.25 μm, Helium; Program: 40 0C (2 min) 5 0C/min -> 140 0C 10 0C/min -> 250 0C (3 min)

References

Baghal-Vayjooee, Collister, et al., 1977
Baghal-Vayjooee, M.H.; Collister, J.L.; Pritchard, H.O., The enthalpy of isomerisation of methyl isocyanide, Can. J. Chem., 1977, 55, 2634-2636. [all data]

Pedley, Naylor, et al., 1986
Pedley, J.B.; Naylor, R.D.; Kirby, S.P., Thermochemical Data of Organic Compounds, Chapman and Hall, New York, 1986, 1-792. [all data]

Lemoult, 1906
Lemoult, P., Carbylamines et nitriles., Compt. Rend., 1906, 143, 902-904. [all data]

Matimba, Crabbendam, et al., 1992
Matimba, H.E.K.; Crabbendam, A.M.; Ingemann, S.; Nibbering, N.M.M., Gas-phase Bimolecular Chemistry of the .-CHNC and .-CHCN Radical Anions, Int. J. Mass Spectrom. Ion Proc., 1992, 114, 1-2, 85, https://doi.org/10.1016/0168-1176(92)85024-T . [all data]

Filley, DePuy, et al., 1987
Filley, J.; DePuy, C.H.; Bierbaum, V.M., Gas-Phase Negative Ion Chemistry of Methyl Isocyanide, J. Am. Chem. Soc., 1987, 109, 20, 5992, https://doi.org/10.1021/ja00254a017 . [all data]

Hunter and Lias, 1998
Hunter, E.P.; Lias, S.G., Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update, J. Phys. Chem. Ref. Data, 1998, 27, 3, 413-656, https://doi.org/10.1063/1.556018 . [all data]

Witt and Grutzmacher, 1997
Witt, M.; Grutzmacher, H.F., The gas phase basicity and proton affinity of propionamide: a comparison of methods, Int. J. Mass Spectrom. Ion. Processes, 1997, 164, 93. [all data]

Harland and McIntosh, 1985
Harland, P.W.; McIntosh, B.J., Enthalpies of formation for the isomeric ions H_xCCN⁺ and H_xCNC⁺ (x = 0-3) by monochromatic electron impact on C₂N₂, CH₃CN and CH₃NC., Int. J. Mass Spectrom. Ion Processes, 1985, 67, 29. [all data]

Chess, Lapp, et al., 1982
Chess, E.K.; Lapp, R.L.; Gross, M.L., The question of tautomerism of alkylnitrile and isonitrile radical cations, Org. Mass Spectrom., 1982, 17, 475. [all data]

Bevan, Sandorfy, et al., 1981
Bevan, J.W.; Sandorfy, C.; Pang, F.; Bogg, J.E., The photoelectron spectrum of methylisocyanide-borane, Spectrochim. Acta A:, 1981, 37, 601. [all data]

Lake and Thompson, 1971
Lake, R.F.; Thompson, H.W., The photoelectron spectra of methyl isocyanide and trideuteromethyl isocyanide, Spectrochim. Acta, 1971, 27A, 783. [all data]

Heerma and deRidder, 1970
Heerma, W.; deRidder, J.J., The electron-impact induced fragmentation of some alkyl isocyanides and alpha-branched alkyl cyanides, Org. Mass Spectrom., 1970, 3, 1439. [all data]

Asbrink, Von Niessen, et al., 1980
Asbrink, L.; Von Niessen, W.; Bieri, G., 30.4-nm He(II) photoelectron spectra of organic molecules, J. Electron Spectrosc. Relat. Phenom., 1980, 21, 93. [all data]

Shimanouchi, 1972
Shimanouchi, T., Tables of Molecular Vibrational Frequencies Consolidated Volume I, National Bureau of Standards, 1972, 1-160. [all data]

Duque, Bonilla, et al., 2001
Duque, C.; Bonilla, A.; Bautista, E.; Zea, S., Exudation of low molecular wight compounds (thiobismethane, methyl isocyanide, amd methyl isothiocyanate) as a possible chemical defense mechanism in the marine sponge Ircinia felix, Biochem. Systematics Ecol., 2001, 29, 5, 459-467, https://doi.org/10.1016/S0305-1978(00)00081-8 . [all data]

Johanningsmeier and McFeeters, 2011
Johanningsmeier, S.D.; McFeeters, R.F., Detection of volatile spoilage metabolites in fermented cucumbers using nontargeted, comprehensive 2-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGCxTOFMS), J. Food Sci., 2011, 76, 1, c168-c177, https://doi.org/10.1111/j.1750-3841.2010.01918.x . [all data]

Notes

Symbols used in this document:

AE Appearance energy

Δ_fH°_gas Enthalpy of formation of gas at standard conditions

Δ_rG° Free energy of reaction at standard conditions

Δ_rH° Enthalpy of reaction at standard conditions
Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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NIST Chemistry WebBook, SRD 69

Methyl isocyanide

Data at NIST subscription sites:

Gas phase thermochemistry data