1H-Imidazole
- Formula: C3H4N2
- Molecular weight: 68.0773
- IUPAC Standard InChIKey: RAXXELZNTBOGNW-UHFFFAOYSA-N
- 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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Gas phase thermochemistry data
Go To: Top, Phase change data, Gas phase ion energetics data, Ion clustering 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:
DRB - Donald R. Burgess, Jr.
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔfH°gas | 129.5 | kJ/mol | N/A | Zaheeruddin and Lodhi, 1991 | Value 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 |
ΔfH°gas | 139.3 ± 1.9 | kJ/mol | Cm | Guthrie and Pike, 1987 | Heat of hydrolysis; ALS |
ΔfH°gas | 132.9 ± 0.6 | kJ/mol | Ccb | Jimenez, Roux, et al., 1987 | see Jimenez, Roux, et al., 1986; ALS |
ΔfH°gas | 128. ± 7.5 | kJ/mol | Ccb | Bedford, Edmondson, et al., 1962 | ALS |
Phase change data
Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Ion clustering 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:
BS - Robert L. Brown and Stephen E. Stein
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DRB - Donald R. Burgess, Jr.
AC - William E. Acree, Jr., James S. Chickos
DH - Eugene S. Domalski and Elizabeth D. Hearing
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
Tboil | 530.2 | K | N/A | Weast and Grasselli, 1989 | BS |
Quantity | Value | Units | Method | Reference | Comment |
Tfus | 363.7 | K | N/A | Hilgeman, Mouroux, et al., 1989 | Uncertainty assigned by TRC = 0.4 K; TRC |
Tfus | 361.9 | K | N/A | De Wit, Offringa, et al., 1983 | Uncertainty assigned by TRC = 0.2 K; TRC |
Quantity | Value | Units | Method | Reference | Comment |
Ttriple | 362.69 | K | N/A | De Wit, De Kruif, et al., 1983 | Uncertainty assigned by TRC = 0.02 K; TRC |
Quantity | Value | Units | Method | Reference | Comment |
ΔsubH° | 79. ± 10. | kJ/mol | AVG | N/A | Average of 8 values; Individual data points |
Enthalpy of sublimation
ΔsubH (kJ/mol) | Temperature (K) | Method | Reference | Comment |
---|---|---|---|---|
83.1 ± 0.2 | 300. | ME | Jimenez, Roux, et al., 1987 | Based on data from 292. to 309. K.; AC |
80.8 | 301. | ME,TE | De Wit, Van Miltenburg, et al., 1983 | Based on data from 288. to 310. K.; AC |
Enthalpy of fusion
ΔfusH (kJ/mol) | Temperature (K) | Reference | Comment |
---|---|---|---|
12.500 | 363.7 | Hilgeman, Mouroux, et al., 1989, 2 | DH |
12.821 | 362.69 | DeWit, DeKruif, et al., 1983 | DH |
12.800 | 361.9 | DeWit, Offringa, et al., 1983 | DH |
12.8 | 361.9 | Domalski and Hearing, 1996 | See also De Wit, De Kruif, et al., 1983, 2.; AC |
Entropy of fusion
ΔfusS (J/mol*K) | Temperature (K) | Reference | Comment |
---|---|---|---|
35.35 | 362.69 | DeWit, DeKruif, et al., 1983 | DH |
35.37 | 361.9 | DeWit, Offringa, et al., 1983 | DH |
Gas phase ion energetics data
Go To: Top, Gas phase thermochemistry data, Phase change data, Ion clustering 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 ± 0.01 | eV | N/A | N/A | L |
Quantity | Value | Units | Method | Reference | Comment |
Proton affinity (review) | 942.8 | kJ/mol | N/A | Hunter and Lias, 1998 | HL |
Quantity | Value | Units | Method | Reference | Comment |
Gas basicity | 909.2 | kJ/mol | N/A | Hunter and Lias, 1998 | HL |
Ionization energy determinations
IE (eV) | Method | Reference | Comment |
---|---|---|---|
8.81 ± 0.01 | PI | Main-Bobo, Loesik, et al., 1986 | LBLHLM |
9.12 | EI | Klebe, Houte, et al., 1972 | LLK |
8.96 | PE | Ramsey, 1979 | Vertical value; LLK |
8.78 | PE | Cradock, Findlay, et al., 1973 | Vertical value; LLK |
Appearance energy determinations
Ion | AE (eV) | Other Products | Method | Reference | Comment |
---|---|---|---|---|---|
CH2N+ | 11.67 ± 0.05 | C2H2N | PI | Main-Bobo, Loesik, et al., 1986 | LBLHLM |
C2H2N+ | 13.2 | HCN | EI | Klebe, Houte, et al., 1972 | LLK |
C2H3N2+ | 11.48 ± 0.02 | CH | PI | Main-Bobo, Loesik, et al., 1986 | LBLHLM |
C3H3N2+ | 12.8 | H | EI | Klebe, Houte, et al., 1972 | LLK |
De-protonation reactions
By formula: C3H3N2- + H+ = C3H4N2
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 1464.1 ± 3.0 | kJ/mol | G+TS | Gianola, Ichino, et al., 2005 | gas phase; B |
ΔrH° | 1465. ± 8.8 | kJ/mol | G+TS | Taft, Anvia, et al., 1986 | gas phase; value altered from reference due to change in acidity scale; B |
Quantity | Value | Units | Method | Reference | Comment |
ΔrG° | 1433.4 ± 1.7 | kJ/mol | IMRE | Gianola, Ichino, et al., 2005 | gas phase; B |
ΔrG° | 1434. ± 8.4 | kJ/mol | IMRE | Taft, Anvia, et al., 1986 | gas phase; value altered from reference due to change in acidity scale; B |
Ion clustering data
Go To: Top, Gas phase thermochemistry data, Phase change 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:
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias
RCD - Robert C. Dunbar
Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. Searches may be limited to ion clustering reactions. A general reaction search form is also available.
Clustering reactions
By formula: C2H3O2- + C3H4N2 = (C2H3O2- • C3H4N2)
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 116. | kJ/mol | PHPMS | Meot-Ner (Mautner), 1988 | gas phase; M |
Quantity | Value | Units | Method | Reference | Comment |
ΔrS° | 102. | J/mol*K | PHPMS | Meot-Ner (Mautner), 1988 | gas phase; M |
By formula: C3H3N2- + C3H4N2 = (C3H3N2- • C3H4N2)
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 110. | kJ/mol | PHPMS | Meot-Ner (Mautner), 1988 | gas phase; M |
Quantity | Value | Units | Method | Reference | Comment |
ΔrS° | 123. | J/mol*K | PHPMS | Meot-Ner (Mautner), 1988 | gas phase; M |
By formula: C3H4N2+ + C3H4N2 = (C3H4N2+ • C3H4N2)
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 99.2 | kJ/mol | PHPMS | Meot-Ner (Mautner), 1988 | gas phase; M |
Quantity | Value | Units | Method | Reference | Comment |
ΔrS° | 90.8 | J/mol*K | PHPMS | Meot-Ner (Mautner), 1988 | gas phase; M |
By formula: C4H12N+ + C3H4N2 = (C4H12N+ • C3H4N2)
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 94.6 | kJ/mol | PHPMS | Meot-Ner (Mautner), 1988 | gas phase; M |
Quantity | Value | Units | Method | Reference | Comment |
ΔrS° | 88.7 | J/mol*K | PHPMS | Meot-Ner (Mautner), 1988 | gas phase; M |
By formula: K+ + C3H4N2 = (K+ • C3H4N2)
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 109. ± 5.4 | kJ/mol | CIDT | Huang and Rodgers, 2002 | RCD |
By formula: Li+ + C3H4N2 = (Li+ • C3H4N2)
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 211. ± 9.6 | kJ/mol | CIDT | Huang and Rodgers, 2002 | RCD |
By formula: Na+ + C3H4N2 = (Na+ • C3H4N2)
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 140. ± 5.0 | kJ/mol | CIDT | Huang and Rodgers, 2002 | RCD |
ΔrH° | 140. ± 5.4 | kJ/mol | CIDT | Armentrout and Rodgers, 2000 | RCD |
ΔrH° | 140. ± 5.0 | kJ/mol | CIDT | Rodgers and Armentrout, 1999 | RCD |
References
Go To: Top, Gas phase thermochemistry data, Phase change data, Gas phase ion energetics data, Ion clustering 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]
Weast and Grasselli, 1989
CRC Handbook of Data on Organic Compounds, 2nd Editon, Weast,R.C and Grasselli, J.G., ed(s)., CRC Press, Inc., Boca Raton, FL, 1989, 1. [all data]
Hilgeman, Mouroux, et al., 1989
Hilgeman, F.R.; Mouroux, F.Y.N.; Mok, D.; Holan, M.K.,
Phase Diagrams of Binary Solid Azole Systems,
J. Chem. Eng. Data, 1989, 34, 220. [all data]
De Wit, Offringa, et al., 1983
De Wit, H.G.M.; Offringa, J.C.A.; De Kruif, C.G.; van Miltenburg, J.C.,
Thremodynamic properties of molecular organic crystals containing nitrogen, oxygen and sulfur. III. molar heat capacities measured by DSC. scanning calorimetry.,
Thermochim. Acta, 1983, 65, 43. [all data]
De Wit, De Kruif, et al., 1983
De Wit, H.G.M.; De Kruif, C.G.; Van Miltenburg, J.C.,
Thermodynamic properties of molecular organic crystals containing nitrogen, oxygen, and sulfur II. Molar heat capacities of eight compounds by adiabatic calorimetry,
J. Chem. Thermodyn., 1983, 15, 9, 891, https://doi.org/10.1016/0021-9614(83)90095-2
. [all data]
De Wit, Van Miltenburg, et al., 1983
De Wit, H.G.M.; Van Miltenburg, J.C.; De Kruif, C.G.,
Thermodynamic properties of molecular organic crystals containing nitrogen, oxygen, and sulphur 1. Vapour pressures and enthalpies of sublimation,
The Journal of Chemical Thermodynamics, 1983, 15, 7, 651-663, https://doi.org/10.1016/0021-9614(83)90079-4
. [all data]
Hilgeman, Mouroux, et al., 1989, 2
Hilgeman, F.R.; Mouroux, F.Y.N.; Mok, D.; Holan, M.K.,
Phase diagrams of binary solid azole systems,
J. Chem. Eng. Data, 1989, 34, 220-222. [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]
Domalski and Hearing, 1996
Domalski, Eugene S.; Hearing, Elizabeth D.,
Heat Capacities and Entropies of Organic Compounds in the Condensed Phase. Volume III,
J. Phys. Chem. Ref. Data, 1996, 25, 1, 1, https://doi.org/10.1063/1.555985
. [all data]
De Wit, De Kruif, et al., 1983, 2
De Wit, H.G.M.; De Kruif, C.G.; Van Miltenburg, J.C.,
Thermodynamic properties of molecular organic crystals containing nitrogen, oxygen, and sulfur II. Molar heat capacities of eight compounds by adiabatic calorimetry,
The Journal of Chemical Thermodynamics, 1983, 15, 9, 891-902, https://doi.org/10.1016/0021-9614(83)90095-2
. [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]
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]
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]
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]
Notes
Go To: Top, Gas phase thermochemistry data, Phase change data, Gas phase ion energetics data, Ion clustering data, References
- Symbols used in this document:
AE Appearance energy IE (evaluated) Recommended ionization energy Tboil Boiling point Tfus Fusion (melting) point Ttriple Triple point temperature ΔfH°gas Enthalpy of formation of gas at standard conditions ΔfusH Enthalpy of fusion ΔfusS Entropy of fusion ΔrG° Free energy of reaction at standard conditions ΔrH° Enthalpy of reaction at standard conditions ΔrS° Entropy of reaction at standard conditions ΔsubH Enthalpy of sublimation ΔsubH° Enthalpy of sublimation at standard conditions - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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