1H-Imidazole

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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

Quantity Value Units Method Reference Comment
Δfgas30.95kcal/molN/AZaheeruddin and Lodhi, 1991Value computed using ΔfHsolid° value of 60.0 kj/mol from Zaheeruddin and Lodhi, 1991 and ΔsubH° value of 69.5 kj/mol from Jimenez, Roux, et al., 1987.; DRB
Δfgas33.29 ± 0.45kcal/molCmGuthrie and Pike, 1987Heat of hydrolysis; ALS
Δfgas31.8 ± 0.1kcal/molCcbJimenez, Roux, et al., 1987see Jimenez, Roux, et al., 1986; ALS
Δfgas30.6 ± 1.8kcal/molCcbBedford, Edmondson, et al., 1962ALS

Condensed 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:
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DH - Eugene S. Domalski and Elizabeth D. Hearing

Quantity Value Units Method Reference Comment
Δfsolid  CcbZaheeruddin and Lodhi, 1991uncertain value: 14.33 kcal/mol; ALS
Δfsolid11.9 ± 0.1kcal/molCcbJimenez, Roux, et al., 1987see Jimenez, Roux, et al., 1986; ALS
Δfsolid13.97 ± 0.78kcal/molCcbBedford, Edmondson, et al., 1962Reanalyzed by Cox and Pilcher, 1970, Original value = 14.6 ± 0.8 kcal/mol; ALS
Quantity Value Units Method Reference Comment
Δcsolid  CcbZaheeruddin and Lodhi, 1991uncertain value: -433.119 kcal/mol; ALS
Δcsolid-430.7 ± 0.1kcal/molCcbJimenez, Roux, et al., 1987see Jimenez, Roux, et al., 1986; ALS
Δcsolid-432.75 ± 0.78kcal/molCcbBedford, Edmondson, et al., 1962Reanalyzed by Cox and Pilcher, 1970, Original value = -433.34 ± 0.78 kcal/mol; ALS
Δcsolid-430.8kcal/molCcbZimmerman and Geisenfelder, 1961ALS

Constant pressure heat capacity of solid

Cp,solid (cal/mol*K) Temperature (K) Reference Comment
19.7298.15Jimenez, Roux, et al., 1987Cp given as 1.21 J/g*K.; DH
21.46300.DeWit, DeKruif, et al., 1983T = 90 to 370 K.; DH
22.6310.DeWit, Offringa, et al., 1983T = 300 to 450 K.; DH

Reaction thermochemistry data

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Gas phase ion energetics data, References, Notes

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

imidazolide anion + Hydrogen cation = 1H-Imidazole

By formula: C3H3N2- + H+ = C3H4N2

Quantity Value Units Method Reference Comment
Δr349.93 ± 0.72kcal/molG+TSGianola, Ichino, et al., 2005gas phase; B
Δr350.1 ± 2.1kcal/molG+TSTaft, Anvia, et al., 1986gas phase; value altered from reference due to change in acidity scale; B
Quantity Value Units Method Reference Comment
Δr342.60 ± 0.40kcal/molIMREGianola, Ichino, et al., 2005gas phase; B
Δr342.8 ± 2.0kcal/molIMRETaft, Anvia, et al., 1986gas phase; value altered from reference due to change in acidity scale; B

Sodium ion (1+) + 1H-Imidazole = (Sodium ion (1+) • 1H-Imidazole)

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

Quantity Value Units Method Reference Comment
Δr33.4 ± 1.2kcal/molCIDTHuang and Rodgers, 2002RCD
Δr33.4 ± 1.3kcal/molCIDTArmentrout and Rodgers, 2000RCD
Δr33.4 ± 1.2kcal/molCIDTRodgers and Armentrout, 1999RCD

imidazolide anion + 1H-Imidazole = (imidazolide anion • 1H-Imidazole)

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

Quantity Value Units Method Reference Comment
Δr26.4kcal/molPHPMSMeot-Ner (Mautner), 1988gas phase; M
Quantity Value Units Method Reference Comment
Δr29.3cal/mol*KPHPMSMeot-Ner (Mautner), 1988gas phase; M

C3H4N2+ + 1H-Imidazole = (C3H4N2+ • 1H-Imidazole)

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

Quantity Value Units Method Reference Comment
Δr23.7kcal/molPHPMSMeot-Ner (Mautner), 1988gas phase; M
Quantity Value Units Method Reference Comment
Δr21.7cal/mol*KPHPMSMeot-Ner (Mautner), 1988gas phase; M

C4H12N+ + 1H-Imidazole = (C4H12N+ • 1H-Imidazole)

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

Quantity Value Units Method Reference Comment
Δr22.6kcal/molPHPMSMeot-Ner (Mautner), 1988gas phase; M
Quantity Value Units Method Reference Comment
Δr21.2cal/mol*KPHPMSMeot-Ner (Mautner), 1988gas phase; M

MeCO2 anion + 1H-Imidazole = (MeCO2 anion • 1H-Imidazole)

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

Quantity Value Units Method Reference Comment
Δr27.7kcal/molPHPMSMeot-Ner (Mautner), 1988gas phase; M
Quantity Value Units Method Reference Comment
Δr24.4cal/mol*KPHPMSMeot-Ner (Mautner), 1988gas phase; M

1H-Imidazole, 1-acetyl- + Water = 1H-Imidazole + Acetic acid

By formula: C5H6N2O + H2O = C3H4N2 + C2H4O2

Quantity Value Units Method Reference Comment
Δr-4.83 ± 0.05kcal/molCmWadso, 1960liquid phase; solvent: Aqueous; Heat of hydrolysis; ALS

Acetylimidazole diethyl acetal + Water = Ethyl Acetate + 1H-Imidazole + Ethanol

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

Quantity Value Units Method Reference Comment
Δr-10.68 ± 0.16kcal/molCmGuthrie and Pike, 1987liquid phase; Heat of hydrolysis; ALS

1-(Dimethoxy-phenylmethyl)-1H-imidazole + Water = 1H-Imidazole + Methyl Alcohol + Benzoic acid, methyl ester

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

Quantity Value Units Method Reference Comment
Δr-13.26 ± 0.17kcal/molCmGuthrie and Pike, 1987liquid phase; Heat of hydrolysis; ALS

N-Formylimidazole diethyl acetal + Water = Ethyl formate + 1H-Imidazole + Ethanol

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

Quantity Value Units Method Reference Comment
Δr-8.28 ± 0.42kcal/molCmGuthrie and Pike, 1987liquid phase; Heat of hydrolysis; ALS

1-Butanamine + 1H-Imidazole, 1-acetyl- = Acetamide, N-butyl- + 1H-Imidazole

By formula: C4H11N + C5H6N2O = C6H13NO + C3H4N2

Quantity Value Units Method Reference Comment
Δr-18.07 ± 0.08kcal/molCmWadso, 1962solid phase; ALS

Lithium ion (1+) + 1H-Imidazole = (Lithium ion (1+) • 1H-Imidazole)

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

Quantity Value Units Method Reference Comment
Δr50.4 ± 2.3kcal/molCIDTHuang and Rodgers, 2002RCD

Potassium ion (1+) + 1H-Imidazole = (Potassium ion (1+) • 1H-Imidazole)

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

Quantity Value Units Method Reference Comment
Δr26.0 ± 1.3kcal/molCIDTHuang and Rodgers, 2002RCD

Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Reaction thermochemistry data, References, Notes

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

Quantity Value Units Method Reference Comment
IE (evaluated)8.81 ± 0.01eVN/AN/AL
Quantity Value Units Method Reference Comment
Proton affinity (review)225.3kcal/molN/AHunter and Lias, 1998HL
Quantity Value Units Method Reference Comment
Gas basicity217.3kcal/molN/AHunter and Lias, 1998HL

Ionization energy determinations

IE (eV) Method Reference Comment
8.81 ± 0.01PIMain-Bobo, Loesik, et al., 1986LBLHLM
9.12EIKlebe, Houte, et al., 1972LLK
8.96PERamsey, 1979Vertical value; LLK
8.78PECradock, Findlay, et al., 1973Vertical value; LLK

Appearance energy determinations

Ion AE (eV) Other Products MethodReferenceComment
CH2N+11.67 ± 0.05C2H2NPIMain-Bobo, Loesik, et al., 1986LBLHLM
C2H2N+13.2HCNEIKlebe, Houte, et al., 1972LLK
C2H3N2+11.48 ± 0.02CHPIMain-Bobo, Loesik, et al., 1986LBLHLM
C3H3N2+12.8HEIKlebe, Houte, et al., 1972LLK

De-protonation reactions

imidazolide anion + Hydrogen cation = 1H-Imidazole

By formula: C3H3N2- + H+ = C3H4N2

Quantity Value Units Method Reference Comment
Δr349.93 ± 0.72kcal/molG+TSGianola, Ichino, et al., 2005gas phase; B
Δr350.1 ± 2.1kcal/molG+TSTaft, Anvia, et al., 1986gas phase; value altered from reference due to change in acidity scale; B
Quantity Value Units Method Reference Comment
Δr342.60 ± 0.40kcal/molIMREGianola, Ichino, et al., 2005gas phase; B
Δr342.8 ± 2.0kcal/molIMRETaft, Anvia, et al., 1986gas phase; value altered from reference due to change in acidity scale; B

References

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, 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]

Cox and Pilcher, 1970
Cox, J.D.; Pilcher, G., Thermochemistry of Organic and Organometallic Compounds, Academic Press, New York, 1970, 1-636. [all data]

Zimmerman and Geisenfelder, 1961
Zimmerman, H.; Geisenfelder, H., Uber die Mesomerieenergie von Azolen, Z. Electrochem., 1961, 65, 368-371. [all data]

DeWit, DeKruif, et al., 1983
DeWit, H.G.M.; DeKruif, C.G.; Van Miltenburg, J.C., Thermodynamic properties of molecular organic crystals containing organic crystals containing nitrogen, oxygen, and sulfur. II. Molar heat capacities of eight compounds by adiabatic calorimetry, J. Chem. Thermodynam., 1983, 15, 891-902. [all data]

DeWit, Offringa, et al., 1983
DeWit, H.G.M.; Offringa, J.C.A.; De Kruif, C.G.; Van Miltenburg, J.C., Thermodynamic properties of molecular organic crystals containing nitrogen, oxygen and sulfur. III. Molar heat capacities measured by differential scanning calorimetry, Thermochim. Acta, 1983, 65, 43-51. [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]


Notes

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, References