1H-Pyrazole
- Formula: C3H4N2
- Molecular weight: 68.0773
- IUPAC Standard InChI: InChI=1S/C3H4N2/c1-2-4-5-3-1/h1-3H,(H,4,5)
- IUPAC Standard InChIKey: WTKZEGDFNFYCGP-UHFFFAOYSA-N
- CAS Registry Number: 288-13-1
- 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: Pyrazole; 1,2-Diazole
- Permanent link for this species. Use this link for bookmarking this species for future reference.
- Information on this page:
- Other data available:
- Data at other public NIST sites:
- Options:
Data at NIST subscription sites:
NIST subscription sites provide data under the NIST Standard Reference Data Program, but require an annual fee to access. The purpose of the fee is to recover costs associated with the development of data collections included in such sites. Your institution may already be a subscriber. Follow the links above to find out more about the data in these sites and their terms of usage.
Condensed phase thermochemistry data
Go To: Top, 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:
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 |
|---|---|---|---|---|---|
| ΔfH°solid | Ccb | Zaheeruddin and Lodhi, 1991 | uncertain value: 26.859 kcal/mol; ALS | ||
| ΔfH°solid | 25.2 ± 0.2 | kcal/mol | Ccb | Jimenez, Roux, et al., 1987 | see Jimenez, Roux, et al., 1986; ALS |
| ΔfH°solid | 27.7 ± 1.1 | kcal/mol | Ccb | Bedford, Edmondson, et al., 1962 | Reanalyzed by Cox and Pilcher, 1970, Original value = 28.3 ± 1.1 kcal/mol; ALS |
| Quantity | Value | Units | Method | Reference | Comment |
| ΔcH°solid | Ccb | Zaheeruddin and Lodhi, 1991 | uncertain value: -445.650 kcal/mol; ALS | ||
| ΔcH°solid | -444.0 ± 0.1 | kcal/mol | Ccb | Jimenez, Roux, et al., 1987 | see Jimenez, Roux, et al., 1986; ALS |
| ΔcH°solid | -446.5 ± 1.1 | kcal/mol | Ccb | Bedford, Edmondson, et al., 1962 | Reanalyzed by Cox and Pilcher, 1970, Original value = -447.1 ± 1.1 kcal/mol; ALS |
| ΔcH°solid | -444.2 | kcal/mol | Ccb | Zimmerman and Geisenfelder, 1961 | ALS |
Constant pressure heat capacity of solid
| Cp,solid (cal/mol*K) | Temperature (K) | Reference | Comment |
|---|---|---|---|
| 19.4 | 298.15 | Jimenez, Roux, et al., 1987 | Cp given as 1.19 J/g*K.; DH |
| 21.0 | 300. | DeWit, Offringa, et al., 1983 | T = 300 to 450 K.; DH |
References
Go To: Top, Condensed phase thermochemistry 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]
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, 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]
Notes
Go To: Top, Condensed phase thermochemistry data, References
- Symbols used in this document:
Cp,solid Constant pressure heat capacity of solid ΔcH°solid Enthalpy of combustion of solid at standard conditions ΔfH°solid Enthalpy of formation of solid at standard conditions - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
- The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment. However, NIST makes no warranties to that effect, and NIST shall not be liable for any damage that may result from errors or omissions in the Database.
- Customer support for NIST Standard Reference Data products.