Azobenzene, (E)-

Formula: C₁₂H₁₀N₂
Molecular weight: 182.2212
IUPAC Standard InChI: InChI=1S/C12H10N2/c1-3-7-11(8-4-1)13-14-12-9-5-2-6-10-12/h1-10H
IUPAC Standard InChIKey: DMLAVOWQYNRWNQ-UHFFFAOYSA-N
CAS Registry Number: 17082-12-1
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.
Species with the same structure:
- Azobenzene
Other names: Diazene, diphenyl-, (E)-; trans-Azobenzene; (E)-Diphenyldiazene; Diazene,diphenyl-,(trans)-
Information on this page:
Other data available:
- Gas phase ion energetics data
- Mass spectrum (electron ionization)
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Data at NIST subscription sites:

NIST / TRC Web Thermo Tables, professional edition (thermophysical and thermochemical data)

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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	96.92 ± 0.31	kcal/mol	Ccr	Steele, Chirico, et al., 1996	Hfusion=21.3±0.5 kJ/mol; ALS
Δ_fH°_gas	96.13 ± 0.65	kcal/mol	Ccb	Dias, Minas Da Piedade, et al., 1992	ALS
Δ_fH°_gas	96.51	kcal/mol	N/A	Schulze, Petrick, et al., 1977	Value computed using Δ_fH_solid° value of 310.2±3.4 kj/mol from Schulze, Petrick, et al., 1977 and Δ_subH° value of 93.6 kj/mol from Steele, Chirico, et al., 1996.; DRB
Δ_fH°_gas	98.85	kcal/mol	N/A	Cole and Gilbert, 1951	Value computed using Δ_fH_solid° value of 320.0 kj/mol from Cole and Gilbert, 1951 and Δ_subH° value of 93.6 kj/mol from Steele, Chirico, et al., 1996.; DRB
Δ_fH°_gas	98.14	kcal/mol	N/A	Corruccini and Gilbert, 1939	Value computed using Δ_fH_solid° value of 317.0±2.0 kj/mol from Corruccini and Gilbert, 1939 and Δ_subH° value of 93.6 kj/mol from Steele, Chirico, et al., 1996.; 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	74.429	kcal/mol	Ccr	Steele, Chirico, et al., 1996	Hfusion=21.3±0.5 kJ/mol; ALS
Δ_fH°_solid	73.76 ± 0.45	kcal/mol	Ccb	Dias, Minas Da Piedade, et al., 1992	ALS
Δ_fH°_solid	74.14 ± 0.81	kcal/mol	Ccb	Schulze, Petrick, et al., 1977	Reanalyzed by Pedley, Naylor, et al., 1986, Original value = 74.40 ± 0.81 kcal/mol; Hfusion=22.6±0.1 kJ/mol; ALS
Δ_fH°_solid	76.49	kcal/mol	Ccb	Cole and Gilbert, 1951	ALS
Δ_fH°_solid	75.7 ± 0.4	kcal/mol	Ccb	Corruccini and Gilbert, 1939	ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_solid	-1544.62 ± 0.21	kcal/mol	Ccr	Steele, Chirico, et al., 1996	Hfusion=21.3±0.5 kJ/mol; ALS
Δ_cH°_solid	-1544.0 ± 0.24	kcal/mol	Ccb	Dias, Minas Da Piedade, et al., 1992	ALS
Δ_cH°_solid	-1544.3 ± 0.81	kcal/mol	Ccb	Schulze, Petrick, et al., 1977	Hfusion=22.6±0.1 kJ/mol; ALS
Δ_cH°_solid	-1546.7	kcal/mol	Ccb	Cole and Gilbert, 1951	ALS
Δ_cH°_solid	-1545.6	kcal/mol	Ccb	Corruccini and Gilbert, 1939	ALS

Constant pressure heat capacity of solid

C_p,solid (cal/mol*K)	Temperature (K)	Reference	Comment
54.7	298.15	Schulze, Petrick, et al., 1977	T = 298 to 333 K. Cp(c) = 229 + 1.086(T - 298.15 K) J/mol*K (298 to 333 K).; DH

Phase change data

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Data compiled as indicated in comments:
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.

Quantity	Value	Units	Method	Reference	Comment
T_fus	339.990	K	N/A	Donnelly, Drewes, et al., 1990	Uncertainty assigned by TRC = 0.2 K; TRC
T_fus	340.50	K	N/A	Cingolani and Berchiesi, 1974	Uncertainty assigned by TRC = 0.5 K; TRC
T_fus	341.	K	N/A	Padoa, 1919	Uncertainty assigned by TRC = 1. K; TRC
T_fus	339.15	K	N/A	Bruner, 1894	Uncertainty assigned by TRC = 0.6 K; TRC
T_fus	342.20	K	N/A	Eykman, 1889	Uncertainty assigned by TRC = 1. K; TRC
Quantity	Value	Units	Method	Reference	Comment
T_triple	341.	K	N/A	Steele, Chirico, et al., 1996	Uncertainty assigned by TRC = 2. K; TRC
T_triple	341.06	K	N/A	Bouwstra, deLeeuw, et al., 1985	Uncertainty assigned by TRC = 0.02 K; TRC
T_triple	341.03	K	N/A	van Miltenburg and Bouwstra, 1984	Uncertainty assigned by TRC = 0.02 K; TRC
Quantity	Value	Units	Method	Reference	Comment
T_c	830.	K	N/A	Steele, Chirico, et al., 1996	Uncertainty assigned by TRC = 3. K; TRC
Quantity	Value	Units	Method	Reference	Comment
P_c	43.42	atm	N/A	Steele, Chirico, et al., 1996	Uncertainty assigned by TRC = 3.45 atm; from extraploation of obs. vapor pressures to Tc; TRC
Quantity	Value	Units	Method	Reference	Comment
ρ_c	1.73	mol/l	N/A	Steele, Chirico, et al., 1996	Uncertainty assigned by TRC = 0.082 mol/l; TRC
Quantity	Value	Units	Method	Reference	Comment
Δ_vapH°	17.4 ± 0.2	kcal/mol	EB	Steele, Chirico, et al., 1996	Based on data from 436. to 626. K.; AC
Quantity	Value	Units	Method	Reference	Comment
Δ_subH°	22.4 ± 0.1	kcal/mol	AVG	N/A	Average of 8 values; Individual data points

Enthalpy of vaporization

Δ_vapH (kcal/mol)	Temperature (K)	Method	Reference	Comment
14.9	391.	A	Stephenson and Malanowski, 1987	Based on data from 376. to 566. K. See also Stull, 1947.; AC

Enthalpy of sublimation

Δ_subH (kcal/mol)	Temperature (K)	Method	Reference	Comment
22.0 ± 0.2	319.	TE,ME	Bouwstra, Oonk, et al., 1984	Based on data from 298. to 341. K.; AC
23.2 ± 0.2	308.	TE	De Kruif and Van Ginkel, 1977	Based on data from 299. to 317. K.; AC
22.7 ± 0.2	308.	ME	De Kruif and Van Ginkel, 1977	Based on data from 299. to 317. K.; AC
22.4 ± 0.29	323.	ME	Schulte, Petrick, et al., 1977	Based on data from 298. to 347. K.; AC

Enthalpy of fusion

Δ_fusH (kcal/mol)	Temperature (K)	Method	Reference	Comment
5.385	341.1	N/A	Domalski and Hearing, 1996	AC
5.413	341.9	DTA	Schulte, Petrick, et al., 1977	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 by: 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

C₁₂H₁₀N₂ = Azobenzene, (E)-

By formula: C₁₂H₁₀N₂ = C₁₂H₁₀N₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-10.8 ± 0.57	kcal/mol	Cpha	Dias, Minas Da Piedade, et al., 1992	solid phase; Photoisomerization
Δ_rH°	-11.5 ± 0.07	kcal/mol	Ciso	Wolf and Cammenga, 1977	solid phase
Δ_rH°	-11.3	kcal/mol	Ciso	Wolf and Cammenga, 1977	gas phase; Gas phase

Gas Chromatography

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

Lee's RI, non-polar column, temperature ramp

View large format table.

Column type	Active phase	I	Reference	Comment
Capillary	HP5-MS	278.	Vrana, Paschke, et al., 2005	30. m/0.25 mm/0.25 μm, Helium, 50. C @ 5. min, 5. K/min, 280. C @ 10. min

References

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

Steele, Chirico, et al., 1996
Steele, W.V.; Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.; Smith, N.K., Thermodynamic properties and ideal-gas enthalpies of formation for butyl vinyl ether, 1,2-dimethoxyethane, methyl glycolate, bicyclo[2.2.1]hept-2-ene, 5-vinylbicyclo[2.2.1]hept-2-ene, trans-azobenzene, butyl acrylate, di-tert-butyl ether, and hexane-1,6-diol, J. Chem. Eng. Data, 1996, 41, 1285-1302. [all data]

Dias, Minas Da Piedade, et al., 1992
Dias, A.R.; Minas Da Piedade, M.E.; Martinho Simoes, J.A.; Simoni, J.A.; Teixeira, C.; Diogo, H.P.; Meng-Yen, Y.; Pilcher, G., Enthalpies of formation of cis-azobenzene and trans-azobenzene, J. Chem. Thermodyn., 1992, 24, 439-447. [all data]

Schulze, Petrick, et al., 1977
Schulze, F.W.; Petrick, H.J.; Cammenga, H.K., Thermodynamic properties of structural analogues benzo[c]cinnoline, trans-azobenzene, and cis-azobenzene, Z. Phys. Chem. (Neue Folge), 1977, 107, 1-19. [all data]

Cole and Gilbert, 1951
Cole, L.G.; Gilbert, E.C., The heats of combustion of some nitrogen compounds and the apparent energy of the N-N bond, J. Am. Chem. Soc., 1951, 73, 5423-5427. [all data]

Corruccini and Gilbert, 1939
Corruccini, R.J.; Gilbert, E.C., The heat of combustion of cis- and trans-azobenzene, J. Am. Chem. Soc., 1939, 61, 2925-2927. [all data]

Pedley, Naylor, et al., 1986
Pedley, J.B.; Naylor, R.D.; Kirby, S.P., Thermochemical Data of Organic Compounds, Chapman and Hall, New York, 1986, 1-792. [all data]

Donnelly, Drewes, et al., 1990
Donnelly, J.R.; Drewes, L.A.; Johnson, R.L.; Munslow, W.D.; Knapp, K.K.; Sovocool, G.W., Purity and heat of fusion data for environmental standards as determined by differential scanning calorimetry, Thermochim. Acta, 1990, 167, 2, 155, https://doi.org/10.1016/0040-6031(90)80476-F . [all data]

Cingolani and Berchiesi, 1974
Cingolani, A.; Berchiesi, G., Thermodynamic properties of organic compounds. 1. A DSC study of phase transitions in aliphatic dicarboxylic acids, J. Therm. Anal., 1974, 6, 87-90. [all data]

Padoa, 1919
Padoa, M., Atti Accad. Naz. Lincei, Cl. Sci. Fis., Mat. Nat., Rend., 1919, 28, 239. [all data]

Bruner, 1894
Bruner, L., The heats of fusion of some organic compounds, Ber. Dtsch. Chem. Ges., 1894, 27, 2102. [all data]

Eykman, 1889
Eykman, J.F., Z. Phys. Chem., Stoechiom. Verwandtschaftsl., 1889, 4, 497. [all data]

Bouwstra, deLeeuw, et al., 1985
Bouwstra, J.A.; deLeeuw, V.V.; van Miltenburg, J.C., Properties of mixed-crystalline organic material prepared by zone levelling 4. melting properties and excess enthalpies of (trans-azobenzene + trans-stilbene), J. Chem. Thermodyn., 1985, 17, 685. [all data]

van Miltenburg and Bouwstra, 1984
van Miltenburg, J.C.; Bouwstra, J.A., Thermodynamic properties of trans-azobenzene and trans-stilbene, J. Chem. Thermodyn., 1984, 16, 61-5. [all data]

Stephenson and Malanowski, 1987
Stephenson, Richard M.; Malanowski, Stanislaw, Handbook of the Thermodynamics of Organic Compounds, 1987, https://doi.org/10.1007/978-94-009-3173-2 . [all data]

Stull, 1947
Stull, Daniel R., Vapor Pressure of Pure Substances. Organic and Inorganic Compounds, Ind. Eng. Chem., 1947, 39, 4, 517-540, https://doi.org/10.1021/ie50448a022 . [all data]

Bouwstra, Oonk, et al., 1984
Bouwstra, J.A.; Oonk, H.A.J.; Blok, J.G.; De Kruif, C.G., Properties of mixed crystalline organic material prepared by zone levelling III. Vapour pressures of (trans-azobenzene + trans-stilbene), The Journal of Chemical Thermodynamics, 1984, 16, 5, 403-409, https://doi.org/10.1016/0021-9614(84)90194-0 . [all data]

De Kruif and Van Ginkel, 1977
De Kruif, C.G.; Van Ginkel, C.H.D., Torsion-weighing effusion vapour-pressure measurements on organic compounds, The Journal of Chemical Thermodynamics, 1977, 9, 8, 725-730, https://doi.org/10.1016/0021-9614(77)90015-5 . [all data]

Schulte, Petrick, et al., 1977
Schulte, F.W.; Petrick, H.-J.; Cammenga, H.K.; Klinge, H., Z. Phys. Chem. (Frankfurt), 1977, 107, 1. [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]

Wolf and Cammenga, 1977
Wolf, E.; Cammenga, H.K., Thermodynamic and kinetic investigation of the thermal isomerization of cis-azobenzene, Z. Phys. Chem. (Neue Folge), 1977, 107, 21-38. [all data]

Vrana, Paschke, et al., 2005
Vrana, B.; Paschke, H.; Paschke, A.; Popp, P.; Schuurmann, G., Performance of semipermeable membrane devices for sampling of organic contaminants in groun water, J. Envirom. Monit., 2005, 7, 5, 500-508, https://doi.org/10.1039/b411645c . [all data]

Notes

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Symbols used in this document:

C_p,solid	Constant pressure heat capacity of solid
P_c	Critical pressure
T_c	Critical temperature
T_fus	Fusion (melting) point
T_triple	Triple point temperature
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_rH°	Enthalpy of reaction at standard conditions
Δ_subH	Enthalpy of sublimation
Δ_subH°	Enthalpy of sublimation at standard conditions
Δ_vapH	Enthalpy of vaporization
Δ_vapH°	Enthalpy of vaporization at standard conditions
ρ_c	Critical density

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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