1H-1,2,4-Triazole

Formula: C₂H₃N₃
Molecular weight: 69.0653
IUPAC Standard InChI: InChI=1S/C2H3N3/c1-3-2-5-4-1/h1-2H,(H,3,4,5)
IUPAC Standard InChIKey: NSPMIYGKQJPBQR-UHFFFAOYSA-N
CAS Registry Number: 288-88-0
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.
Species with the same structure:
- 4H-1,2,4-triazole
Other names: s-Triazole; 1,2,4-Triazole; 1,2,4-1H-Triazole; CGA-71019; Pyrrodiazole
Information on this page:
Other data available:
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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	46.1 ± 0.2	kcal/mol	Ccb	Jimenez, Roux, et al., 1989	ALS
Δ_fH°_gas	46.30 ± 0.45	kcal/mol	Ccb	Faour and Akasheh, 1985	ALS
Δ_fH°_gas	45.05	kcal/mol	N/A	Masalitinova, Oleinikova, et al., 1984	Value computed using Δ_fH_solid° value of 107.9±0.5 kj/mol from Masalitinova, Oleinikova, et al., 1984 and Δ_subH° value of 80.6 kj/mol from Jimenez, Roux, et al., 1989.; DRB
Δ_fH°_gas	45.36	kcal/mol	N/A	Aleksandrov, Osipova, et al., 1982	Value computed using Δ_fH_solid° value of 109.2±0.9 kj/mol from Aleksandrov, Osipova, et al., 1982 and Δ_subH° value of 80.6 kj/mol from Jimenez, Roux, et al., 1989.; DRB

Condensed phase thermochemistry data

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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
Δ_fH°_solid	25.98 ± 0.1	kcal/mol	Ccb	Jimenez, Roux, et al., 1989	ALS
Δ_fH°_solid	27.03 ± 0.33	kcal/mol	Ccb	Faour and Akasheh, 1985	ALS
Δ_fH°_solid	25.79 ± 0.11	kcal/mol	Ccb	Masalitinova, Oleinikova, et al., 1984	ALS
Δ_fH°_solid	26.10 ± 0.22	kcal/mol	Ccb	Aleksandrov, Osipova, et al., 1982	ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_solid	-316.54 ± 0.07	kcal/mol	Ccb	Jimenez, Roux, et al., 1989	ALS
Δ_cH°_solid	-317.61 ± 0.29	kcal/mol	Ccb	Faour and Akasheh, 1985	ALS
Δ_cH°_solid	-316.362 ± 0.088	kcal/mol	Ccb	Masalitinova, Oleinikova, et al., 1984	ALS
Δ_cH°_solid	-316.68 ± 0.22	kcal/mol	Ccb	Aleksandrov, Osipova, et al., 1982	ALS
Δ_cH°_solid	-316.8	kcal/mol	Ccb	Zimmerman and Geisenfelder, 1961	ALS

Constant pressure heat capacity of solid

C_p,solid (cal/mol*K)	Temperature (K)	Reference	Comment
18.8	298.15	Jimenez, Roux, et al., 1989	DH

Phase change data

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Data compiled as indicated in comments:
BS - Robert L. Brown and Stephen E. Stein
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
AC - William E. Acree, Jr., James S. Chickos
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DRB - Donald R. Burgess, Jr.
DH - Eugene S. Domalski and Elizabeth D. Hearing

Quantity	Value	Units	Method	Reference	Comment
T_boil	533.2	K	N/A	Aldrich Chemical Company Inc., 1990	BS
T_boil	477.15	K	N/A	Bruhl, 1895	Uncertainty assigned by TRC = 1.5 K; TRC
Quantity	Value	Units	Method	Reference	Comment
T_fus	393.5	K	N/A	Hilgeman, Mouroux, et al., 1989	Uncertainty assigned by TRC = 0.4 K; TRC
T_fus	392.	K	N/A	Vorontsova and Vlasov, 1987	Crystal phase 1 phase; Uncertainty assigned by TRC = 0.5 K; TRC
T_fus	295.15	K	N/A	Bruhl, 1895	Uncertainty assigned by TRC = 1.5 K; TRC
Quantity	Value	Units	Method	Reference	Comment
Δ_subH°	19.8 ± 0.7	kcal/mol	AVG	N/A	Average of 6 values; Individual data points

Enthalpy of fusion

Δ_fusH (kcal/mol)	Temperature (K)	Reference	Comment
3.8480	393.5	Hilgeman, Mouroux, et al., 1989, 2	DH
2.57 ± 0.02	393.3	Sabbah and Perez, 1999	AC
3.85	393.5	Domalski and Hearing, 1996	AC

In addition to the Thermodynamics Research Center (TRC) data available from this site, much more physical and chemical property data is available from the following TRC products:

Reaction thermochemistry data

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Data compiled as indicated in comments:
B - John E. Bartmess
RCD - Robert C. Dunbar
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

C₂H₂N₃^- + = 1H-1,2,4-Triazole

By formula: C₂H₂N₃^- + H⁺ = C₂H₃N₃

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	344.2 ± 2.1	kcal/mol	G+TS	Taft, 1991	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	336.9 ± 2.0	kcal/mol	IMRE	Taft, 1991	gas phase; B

+ 1H-1,2,4-Triazole = ( • )

By formula: Na⁺ + C₂H₃N₃ = (Na⁺ • C₂H₃N₃)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	29.6 ± 1.2	kcal/mol	CIDT	Rodgers and Armentrout, 2000	RCD

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
0.0	0.	CIDT	Rodgers and Armentrout, 2000	RCD

+ = 1H-1,2,4-Triazole +

By formula: C₄H₅N₃O + H₂O = C₂H₃N₃ + C₂H₄O₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-7.29 ± 0.06	kcal/mol	Cm	Wadso, 1960	solid phase; Heat of hydrolysis; ALS

+ = + 1H-1,2,4-Triazole

By formula: C₄H₁₁N + C₄H₅N₃O = C₆H₁₃NO + C₂H₃N₃

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-20.50 ± 0.06	kcal/mol	Cm	Wadso, 1962	solid phase; ALS

= 1H-1,2,4-Triazole

By formula: C₂H₃N₃ = C₂H₃N₃

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	2.8	kcal/mol	Eqk	Mauret, Fayet, et al., 1973	liquid phase; solvent: Benzene; ALS

+ = + 1H-1,2,4-Triazole

By formula: C₄H₅N₃O + C₆H₇N = C₈H₉NO + C₂H₃N₃

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-17.28 ± 0.08	kcal/mol	Cm	Wadso, 1962	solid phase; ALS

+ 1H-1,2,4-Triazole = ( • )

By formula: Li⁺ + C₂H₃N₃ = (Li⁺ • C₂H₃N₃)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	45.7 ± 1.9	kcal/mol	CIDT	Rodgers and Armentrout, 2000	RCD

+ 1H-1,2,4-Triazole = ( • )

By formula: K⁺ + C₂H₃N₃ = (K⁺ • C₂H₃N₃)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	20.8 ± 1.2	kcal/mol	CIDT	Rodgers and Armentrout, 2000	RCD

References

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

Jimenez, Roux, et al., 1989
Jimenez, P.; Roux, M.V.; Turrion, C., Thermochemical properties of N-heterocyclic compounds II. Enthalpies of combustion, vapour pressures, enthalpies of sublimation, and enthalpies of formation of 1,2,4-triazole and benzotriazole, J. Chem. Thermodyn., 1989, 21, 759-764. [all data]

Faour and Akasheh, 1985
Faour, M.; Akasheh, T.S., Heat of combustion of some N-heterocycle compounds. Part 1, J. Chem. Soc. Perkin Trans. 2, 1985, 811-713. [all data]

Masalitinova, Oleinikova, et al., 1984
Masalitinova, T.N.; Oleinikova, T.P.; Polyakova, L.P., Thermochemical study of 1,2,4-triazole as a reference substnace for the calorimetry of combustion of organonitrogen compounds, Ref. Zh., Khim.; Abstr. No. 7B3028, 1984, 0. [all data]

Aleksandrov, Osipova, et al., 1982
Aleksandrov, Yu.I.; Osipova, T.R.; Yuhkevich, V.F., Study of 1,2,4-triazole as a standard sample in the calorimetry of thoroughly nitrided organic compounds, Termodin. Organ. Soedin., 1982, 42-45. [all data]

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

Aldrich Chemical Company Inc., 1990
Aldrich Chemical Company Inc., Catalog Handbook of Fine Chemicals, Aldrich Chemical Company, Inc., Milwaukee WI, 1990, 1. [all data]

Bruhl, 1895
Bruhl, J.W., Spectrochemistry of Nitrogen-Containing Compounds. I., Z. Phys. Chem., Stoechiom. Verwandtschaftsl., 1895, 16, 193. [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]

Vorontsova and Vlasov, 1987
Vorontsova, N.A.; Vlasov, O.N., Determination of saturated vapor pressure of Bayletone and its semiproducts, Deposited Doc. ONIITEkhim Cherkassy, 1987, Doc. No. 1423 khp - 87, 1987. [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]

Sabbah and Perez, 1999
Sabbah, Raphaël; Perez, Laurence, Energetics of Intramolecular Bonds in 1H-1,2,4-Triazole and 1H-Benzotriazole, Aust. J. Chem., 1999, 52, 4, 235-621, https://doi.org/10.1071/C99006 . [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]

Taft, 1991
Taft, R.W., , personal communication, Aug, 1991. [all data]

Rodgers and Armentrout, 2000
Rodgers, M.T.; Armentrout, P.B., Noncovalent Metal-Ligand Bond Energies as Studied by Threshold Collision-Induced Dissociation, Mass Spectrom. Rev., 2000, 19, 4, 215, https://doi.org/10.1002/1098-2787(200007)19:4<215::AID-MAS2>3.0.CO;2-X . [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]

Mauret, Fayet, et al., 1973
Mauret, P.; Fayet, J.P.; Fabre, M.; Elguero, J.; Pardo, M.d.C., Tautomerism study of υ-triazole from dipolar moment measurements, J. Chim. Phys. Phys.-Chim. Biol., 1973, 70, 1483-1485. [all data]

Notes

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Symbols used in this document:

C_p,solid	Constant pressure heat capacity of solid
T	Temperature
T_boil	Boiling point
T_fus	Fusion (melting) point
Δ_cH°_solid	Enthalpy of combustion of solid at standard conditions
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions
Δ_fH°_solid	Enthalpy of formation of solid at standard conditions
Δ_fusH	Enthalpy of fusion
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions
Δ_subH°	Enthalpy of sublimation at standard conditions

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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