Selected ATcT [1, 2] enthalpy of formation based on version 1.176 of the Thermochemical Network [3]

This version of ATcT results[3] was generated by additional expansion of version 1.172 to include species related to Criegee intermediates that are involved in several ongoing studies[4].

p-Benzyne

Formula: C6H4 (g)

CAS RN: 3355-34-8

ATcT ID: 3355-34-8*0

SMILES: c1c[c]cc[c]1

InChI: InChI=1S/C6H4/c1-2-4-6-5-3-1/h1-2,5-6H

InChIKey: AIESRBVWAFETPR-UHFFFAOYSA-N

Hills Formula: C6H4

2D Image:

Aliases: C6H4; p-Benzyne; 1,4-Benzyne; p-Phenylene; 1,4-Phenylene; p-Didehydrobenzene; 1,4-Didehydrobenzene; 2,5-Cyclohexadiene-1,4-diylidene; p-C6H4

Relative Molecular Mass: 76.0960 ± 0.0048

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
587.0	577.6	± 1.2	kJ/mol

3D Image of C6H4 (g)

spin ON spin OFF

Top contributors to the provenance of Δ_fH° of C6H4 (g)

The 20 contributors listed below account only for 59.2% of the provenance of Δ_fH° of C6H4 (g).
A total of 64 contributors would be needed to account for 90% of the provenance.

Please note: The list is limited to 20 most important contributors or, if less, a number sufficient to account for 90% of the provenance. The Reference acts as a further link to the relevant references and notes for the measurement. The Measured Quantity is normaly given in the original units; in cases where we have reinterpreted the original measurement, the listed value may differ from that given by the authors. The quoted uncertainty is the a priori uncertainty used as input when constructing the initial Thermochemical Network, and corresponds either to the value proposed by the original authors or to our estimate; if an additional multiplier is given in parentheses immediately after the prior uncertainty, it corresponds to the factor by which the prior uncertainty needed to be multiplied during the ATcT analysis in order to make that particular measurement consistent with the prevailing knowledge contained in the Thermochemical Network.

Contribution (%)	TN ID	Reaction	Measured Quantity	Reference
7.4	6937.7	C6H4 (g, triplet) → 6 C (g) + 4 H (g)	Δ_rH°(0 K) = 1082.46 ± 0.70 kcal/mol	Karton 2009a
4.7	6944.1	C6H4 (g, singlet) → C6H4 (g, triplet)	Δ_rH°(0 K) = 0.165 ± 0.016 eV	Wenthold 1998
4.0	6936.5	C6H4 (g, singlet) → 6 C (g) + 4 H (g)	Δ_rH°(0 K) = 1085.45 ± 1.35 kcal/mol	Karton 2009a
4.0	6949.5	C6H4 (g, singlet) → C6H4 (g, singlet)	Δ_rH°(0 K) = -14.08 ± 0.8 kcal/mol	Karton 2009a
3.9	6936.6	C6H4 (g, singlet) → 6 C (g) + 4 H (g)	Δ_rH°(0 K) = 1087.73 ± 0.70 (×1.957) kcal/mol	Karton 2009a
3.4	6939.1	[C6H4]- (g) → C6H4 (g, singlet)	Δ_rH°(0 K) = 1.265 ± 0.008 eV	Wenthold 1998
3.2	6936.4	C6H4 (g, singlet) → 6 C (g) + 4 H (g)	Δ_rH°(0 K) = 1085.44 ± 1.50 kcal/mol	Ruscic W1RO
2.9	6947.1	C6H4 (g, singlet) → C6H4 (g, singlet)	Δ_rH°(0 K) = -27.33 ± 1.0 (×1.091) kcal/mol	Ruscic G4
2.8	6936.2	C6H4 (g, singlet) → 6 C (g) + 4 H (g)	Δ_rH°(0 K) = 1087.65 ± 1.60 kcal/mol	Ruscic G4
2.5	6915.9	C6H4 (g, singlet) → HCCCCH (g) + HCCH (g)	Δ_rH°(0 K) = 52.4 ± 0.5 kcal/mol	Zhang 2007
2.5	6953.4	[C6H4]- (g) → [C6H4]- (g)	Δ_rH°(0 K) = -11.49 ± 0.9 kcal/mol	Ruscic W1RO
2.4	6947.4	C6H4 (g, singlet) → C6H4 (g, singlet)	Δ_rH°(0 K) = -29.28 ± 1.2 kcal/mol	Karton 2009a
2.2	6916.7	C6H6 (g) → C6H4 (g, singlet) + H2 (g)	Δ_rH°(0 K) = 88.10 ± 0.6 kcal/mol	Karton 2009a
2.0	6953.1	[C6H4]- (g) → [C6H4]- (g)	Δ_rH°(0 K) = -13.05 ± 1.0 kcal/mol	Ruscic G4
2.0	6937.6	C6H4 (g, triplet) → 6 C (g) + 4 H (g)	Δ_rH°(0 K) = 1082.27 ± 1.35 kcal/mol	Karton 2009a
1.9	6947.5	C6H4 (g, singlet) → C6H4 (g, singlet)	Δ_rH°(0 K) = -27.07 ± 0.8 (×1.682) kcal/mol	Karton 2009a
1.7	6952.4	[C6H4]- (g) → [C6H4]- (g)	Δ_rH°(0 K) = -5.08 ± 0.9 kcal/mol	Ruscic W1RO
1.7	6940.1	[C6H4]- (g) → C6H4 (g, triplet)	Δ_rH°(0 K) = 1.430 ± 0.015 eV	Wenthold 1998
1.7	6949.3	C6H4 (g, singlet) → C6H4 (g, singlet)	Δ_rH°(0 K) = -15.46 ± 0.9 (×1.354) kcal/mol	Ruscic W1RO
1.6	6937.5	C6H4 (g, triplet) → 6 C (g) + 4 H (g)	Δ_rH°(0 K) = 1082.70 ± 1.50 kcal/mol	Ruscic W1RO

Top 10 species with enthalpies of formation correlated to the Δ_fH° of C6H4 (g)

Please note: The correlation coefficients are obtained by renormalizing the off-diagonal elements of the covariance matrix by the corresponding variances.
The correlation coefficient is a number from -1 to 1, with 1 representing perfectly correlated species, -1 representing perfectly anti-correlated species, and 0 representing perfectly uncorrelated species.

Correlation Coefficent (%)	Species Name	Formula	Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units	Relative Molecular Mass	ATcT ID
100.0	p-Benzyne	C6H4 (g, singlet)	587.0	577.5	± 1.2	kJ/mol	76.0960 ± 0.0048	3355-34-8*2
84.0	p-Benzyne anion	[C6H4]- (g)	465.1	455.5	± 1.3	kJ/mol	76.0965 ± 0.0048	219298-17-6*0
70.8	p-Benzyne	C6H4 (g, triplet)	603.5	594.2	± 1.2	kJ/mol	76.0960 ± 0.0048	3355-34-8*1
46.0	o-Benzyne	C6H4 (g, singlet)	468.19	459.27	± 0.85	kJ/mol	76.0960 ± 0.0048	462-80-6*2
46.0	o-Benzyne	C6H4 (g)	468.19	459.27	± 0.85	kJ/mol	76.0960 ± 0.0048	462-80-6*0
45.5	o-Benzyne anion	[C6H4]- (g)	413.81	404.70	± 0.95	kJ/mol	76.0965 ± 0.0048	100569-88-8*0
44.7	m-Benzyne	C6H4 (g, singlet)	527.4	518.9	± 1.2	kJ/mol	76.0960 ± 0.0048	1828-89-3*2
44.7	m-Benzyne	C6H4 (g)	527.4	518.9	± 1.2	kJ/mol	76.0960 ± 0.0048	1828-89-3*0
44.0	o-Benzyne	C6H4 (g, triplet)	625.7	616.4	± 1.1	kJ/mol	76.0960 ± 0.0048	462-80-6*1
42.4	m-Benzyne anion	[C6H4]- (g)	444.5	435.6	± 1.3	kJ/mol	76.0965 ± 0.0048	249589-31-9*0

Most Influential reactions involving C6H4 (g)

Please note: The list, which is based on a hat (projection) matrix analysis, is limited to no more than 20 largest influences.

Influence Coefficient	TN ID	Reaction	Measured Quantity	Reference
1.000	6943.1	C6H4 (g) → C6H4 (g, singlet)	Δ_rH°(0 K) = 0 ± 0 cm-1	triv, Ruscic W1RO, Ruscic G4, Ruscic CBS-n
0.005	6948.2	C6H4 (g) → C6H4 (g)	Δ_rH°(298.15 K) = -16.1 ± 4 kcal/mol	Wenthold 2010, est unc
0.004	6946.2	C6H4 (g) → C6H4 (g)	Δ_rH°(298.15 K) = -30.7 ± 4 kcal/mol	Wenthold 2010, est unc
0.002	6948.1	C6H4 (g) → C6H4 (g)	Δ_rH°(298.15 K) = -15.3 ± 6 kcal/mol	Wenthold 1994, est unc
0.001	6946.1	C6H4 (g) → C6H4 (g)	Δ_rH°(298.15 K) = -30.7 ± 6 kcal/mol	Wenthold 1994, est unc

References

1		B. Ruscic, R. E. Pinzon, M. L. Morton, G. von Laszewski, S. Bittner, S. G. Nijsure, K. A. Amin, M. Minkoff, and A. F. Wagner, Introduction to Active Thermochemical Tables: Several "Key" Enthalpies of Formation Revisited. J. Phys. Chem. A 108, 9979-9997 (2004) [DOI: 10.1021/jp047912y]
2		B. Ruscic, R. E. Pinzon, G. von Laszewski, D. Kodeboyina, A. Burcat, D. Leahy, D. Montoya, and A. F. Wagner, Active Thermochemical Tables: Thermochemistry for the 21^st Century. J. Phys. Conf. Ser. 16, 561-570 (2005) [DOI: 10.1088/1742-6596/16/1/078]
3		B. Ruscic and D. H. Bross, Active Thermochemical Tables (ATcT) values based on ver. 1.176 of the Thermochemical Network (2024); available at ATcT.anl.gov
4		T. L. Nguyen et al, ongoing studies (2024)
5		B. Ruscic, Uncertainty Quantification in Thermochemistry, Benchmarking Electronic Structure Computations, and Active Thermochemical Tables. Int. J. Quantum Chem. 114, 1097-1101 (2014) [DOI: 10.1002/qua.24605]
6		B. Ruscic and D. H. Bross, Thermochemistry Computer Aided Chem. Eng. 45, 3-114 (2019) [DOI: 10.1016/B978-0-444-64087-1.00001-2]

Formula

The aggregate state is given in parentheses following the formula, such as: g - gas-phase, cr - crystal, l - liquid, etc.

Uncertainties

The listed uncertainties correspond to estimated 95% confidence limits, as customary in thermochemistry (see, for example, Ruscic [5] and Ruscic and Bross[6]).
Note that an uncertainty of ± 0.000 kJ/mol indicates that the estimated uncertainty is < ± 0.000₅ kJ/mol.

Website Functionality Credits

The reorganization of the website was developed and implemented by David H. Bross (ANL).
The find function is based on the complete Species Dictionary entries for the appropriate version of the ATcT TN.
The molecule images are rendered by Indigo-depict.
The XYZ renderings are based on Jmol: an open-source Java viewer for chemical structures in 3D. http://www.jmol.org/.

Acknowledgement

This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences under Contract No. DE-AC02-06CH11357.