1H-Imidazole

• Formula: C₃H₄N₂
• Molecular weight: 68.0773
• IUPAC Standard InChI: InChI=1S/C3H4N2/c1-2-5-3-4-1/h1-3H,(H,4,5) Copy

  
• IUPAC Standard InChIKey: RAXXELZNTBOGNW-UHFFFAOYSA-N Copy
• CAS Registry Number: 288-32-4
• Chemical structure:
  This structure is also available as a 2d Mol file or as a computed 3d SD file
  The 3d structure may be viewed using Java or Javascript.
• Other names: Imidazole; Glyoxalin; Glyoxaline; Imidazol; Imutex; Methanimidamide, N,N'-1,2-ethenediyl-; Miazole; 1,3-Diaza-2,4-cyclopentadiene; 1,3-Diazole; Formamidine, N,N'-vinylene-; Iminazole; IMD; Pyrro(b)monazole; USAF EK-4733; NSC 60522
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• Information on this page:
  • Gas phase thermochemistry data
  • Reaction thermochemistry data
  • Gas phase ion energetics data
  • Mass spectrum (electron ionization)
  • UV/Visible spectrum
  • References
  • Notes
• Other data available:
  • Condensed phase thermochemistry data
  • Phase change data
  • Ion clustering data
  • IR Spectrum
  • Gas Chromatography
• Data at other public NIST sites:
  • X-ray Photoelectron Spectroscopy Database, version 5.0
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Gas phase thermochemistry data

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

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

Reaction thermochemistry data

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled as indicated in comments:
B - John E. Bartmess
RCD - Robert C. Dunbar
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias
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

 +  =

By formula: C₃H₃N₂^- + H⁺ = C₃H₄N₂

 +  = ( • )

By formula: Na⁺ + C₃H₄N₂ = (Na⁺ • C₃H₄N₂)

 +  = ( • )

By formula: C₃H₃N₂^- + C₃H₄N₂ = (C₃H₃N₂^- • C₃H₄N₂)

C₃H₄N₂⁺ +  = (C₃H₄N₂⁺ • )

By formula: C₃H₄N₂⁺ + C₃H₄N₂ = (C₃H₄N₂⁺ • C₃H₄N₂)

C₄H₁₂N⁺ +  = (C₄H₁₂N⁺ • )

By formula: C₄H₁₂N⁺ + C₃H₄N₂ = (C₄H₁₂N⁺ • C₃H₄N₂)

 +  = ( • )

By formula: C₂H₃O₂^- + C₃H₄N₂ = (C₂H₃O₂^- • C₃H₄N₂)

 +  =  + 

By formula: C₅H₆N₂O + H₂O = C₃H₄N₂ + C₂H₄O₂

 +  =  +  + 

By formula: C₉H₁₆N₂O₂ + H₂O = C₄H₈O₂ + C₃H₄N₂ + C₂H₆O

 +  =  +  + 

By formula: C₁₂H₁₄N₂O₂ + H₂O = C₃H₄N₂ + CH₄O + C₈H₈O₂

 +  =  +  + 

By formula: C₈H₁₄N₂O₂ + H₂O = C₃H₆O₂ + C₃H₄N₂ + C₂H₆O

 +  =  + 

By formula: C₄H₁₁N + C₅H₆N₂O = C₆H₁₃NO + C₃H₄N₂

 +  = ( • )

By formula: Li⁺ + C₃H₄N₂ = (Li⁺ • C₃H₄N₂)

 +  = ( • )

By formula: K⁺ + C₃H₄N₂ = (K⁺ • C₃H₄N₂)

Gas phase ion energetics data

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

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

Data compiled as indicated in comments:
B - John E. Bartmess
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

Ionization energy determinations

Appearance energy determinations

De-protonation reactions

 +  =

By formula: C₃H₃N₂^- + H⁺ = C₃H₄N₂

Mass spectrum (electron ionization)

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

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

Spectrum

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Additional Data

UV/Visible spectrum

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: Victor Talrose, Alexander N. Yermakov, Alexy A. Usov, Antonina A. Goncharova, Axlexander N. Leskin, Natalia A. Messineva, Natalia V. Trusova, Margarita V. Efimkina

Spectrum

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Additional Data

References

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, Mass spectrum (electron ionization), UV/Visible spectrum, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Zaheeruddin and Lodhi, 1991
Zaheeruddin, M.; Lodhi, Z.H., Enthalpies of formation of some cyclic compounds, Phys. Chem. (Peshawar Pak.), 1991, 10, 111-118. [all data]

Jimenez, Roux, et al., 1987
Jimenez, P.; Roux, M.V.; Turrion, C., Thermochemical properties of N-heterocyclic compounds. I. Enthalpies of combustion, vapour pressures and enthalpies of sublimation, and enthalpies of formation of pyrazole, imidazole, indazole, and benzimidazole, J. Chem. Thermodyn., 1987, 19, 985-992. [all data]

Guthrie and Pike, 1987
Guthrie, J.P.; Pike, D.C., Hydration of acylimidazoles: tetrahedral intermediates in acylimidazole hydrolysis and nucleophilic attack by imidazole on esters. The question of concerted mechanisms for acyl transfers, Can. J. Chem., 1987, 65, 1951-1969. [all data]

Jimenez, Roux, et al., 1986
Jimenez, P.; Roux, M.V.; Turrion, C.; Gomis, F., Thermochemical properties of some N-heterocyclic compounds, J. Calorim. Anal. Therm. Thermodyn. Chim., 1986, 17, 469-470. [all data]

Bedford, Edmondson, et al., 1962
Bedford, A.F.; Edmondson, P.B.; Mortimer, C.T., Heats of formation and bond energies. Part VI. n-Butyliso-butyraldimine, n-butylisobutylamine, pyrazole, and imidazole, J. Chem. Soc., 1962, 2927-2931. [all data]

Gianola, Ichino, et al., 2005
Gianola, A.J.; Ichino, T.; Hoenigman, R.L.; Kato, S.; Bierbaum, V.M.; Lineberger, W.C., Photoelectron spectra and ion chemistry of imidazolide, J. Phys. Chem. A, 2005, 109, 50, 11504-11514, https://doi.org/10.1021/jp053566o . [all data]

Taft, Anvia, et al., 1986
Taft, R.W.; Anvia, F.; Taagepera, M.; Catalan, J.; Elgueroy, J., Electrostatic proximity effects in the relative basicities of pyrazole, imidazole, pyridazine, and pyrimidine, J. Am. Chem. Soc., 1986, 108, 3237. [all data]

Huang and Rodgers, 2002
Huang, H.; Rodgers, M.T., Sigma versus Pi interactions in alkali metal ion binding to azoles: Threshold collision-induced dissociation and ab initio theory studies, J. Phys. Chem. A, 2002, 106, 16, 4277, https://doi.org/10.1021/jp013630b . [all data]

Armentrout and Rodgers, 2000
Armentrout, P.B.; Rodgers, M.T., An Absolute Sodium Cation Affinity Scale: Threshold Collision-Induced Dissociation Experiments and ab Initio Theory, J. Phys. Chem A, 2000, 104, 11, 2238, https://doi.org/10.1021/jp991716n . [all data]

Rodgers and Armentrout, 1999
Rodgers, M.T.; Armentrout, P.B., Absolute Alkali Metal Ion Binding Affinities of Several Azoles Determined by Threshold Collision-Induced Dissociation, Int. J. Mass Spectrom. Ion Proc., 1999, 185/186/187, 359. [all data]

Meot-Ner (Mautner), 1988
Meot-Ner (Mautner), M., Models for Strong Interactions in Proteins and Enzymes. 2. Interactions of Ions with the Peptide Link and Imidazole, J. Am. Chem. Soc., 1988, 110, 10, 3075, https://doi.org/10.1021/ja00218a014 . [all data]

Wadso, 1960
Wadso, I., Heats of hydrolysis of N-acetylated imidazole, 1,2,4-triazole and tetrazole, Acta Chem. Scand., 1960, 14, 903-908. [all data]

Wadso, 1962
Wadso, I., Heats of aminolysis and hydrolysis of some N-acetyl compounds and of acetic anhydride, Acta Chem. Scand., 1962, 16, 471-478. [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]

Main-Bobo, Loesik, et al., 1986
Main-Bobo, J.; Loesik, S.; Gase, W.; Baer, T.; Mommers, A.; Holmes, J., The thermochemistry and dissociation dynamics of internal-energy selected pyrazole and imidazole ions, J. Am. Chem. Soc., 1986, 108, 677. [all data]

Klebe, Houte, et al., 1972
Klebe, K.J.; Houte, J.J.V.; Thuijl, J.V., Loss of HCN and H from the molecular ion of imidazole, Org. Mass Spectrom., 1972, 6, 1363. [all data]

Ramsey, 1979
Ramsey, B.G., Substituent effects on imidazole basicity and photoelectron spectroscopy determined ionization energies, J. Org. Chem., 1979, 44, 2093. [all data]

Cradock, Findlay, et al., 1973
Cradock, S.; Findlay, R.H.; Palmer, M.H., The molecular energy levels of the azoles: A study by photoelectron spectroscopy and ab initio molecular orbital calculations, Tetrahedron, 1973, 29, 2173. [all data]

Johnson, 1967
Johnson, E.A., UV atlas of organic compounds, 1967, 3, G1/7. [all data]

Notes

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• Symbols used in this document:
  

  AE	Appearance energy
  IE (evaluated)	Recommended ionization energy
  ΔfH°gas	Enthalpy of formation of gas at standard conditions
  ΔrG°	Free energy of reaction at standard conditions
  ΔrH°	Enthalpy of reaction at standard conditions
  ΔrS°	Entropy of reaction at standard conditions

• Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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