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].

Ketene

Formula: CH2CO (g, para singlet)

CAS RN: 463-51-4

ATcT ID: 463-51-4*21

SMILES: C=C=O

InChI: InChI=1S/C2H2O/c1-2-3/h1H2

InChIKey: CCGKOQOJPYTBIH-UHFFFAOYSA-N

Hills Formula: C2H2O1

2D Image:

Aliases: CH2CO; Ketene; Ethenone; Carbomethene; H2CCO; H2C=C=O

Relative Molecular Mass: 42.0367 ± 0.0016

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
-45.34	-48.40	± 0.11	kJ/mol

3D Image of CH2CO (g, para singlet)

spin ON spin OFF

Top contributors to the provenance of Δ_fH° of CH2CO (g, para singlet)

The 20 contributors listed below account only for 52.9% of the provenance of Δ_fH° of CH2CO (g, para singlet).
A total of 248 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
11.0	2424.1	CH2 (g, triplet) → CH2 (g, singlet)	Δ_rH°(0 K) = 3147 ± 5 cm-1	Jensen 1988, Jacox 1994
6.4	2412.9	CH2 (g, triplet) → C (g) + 2 H (g)	Δ_rH°(0 K) = 179.80 ± 0.06 kcal/mol	Feller 2016, note unc2
5.5	2286.9	C (graphite) + CO2 (g) → 2 CO (g)	Δ_rG°(1165 K) = -33.545 ± 0.058 kJ/mol	Smith 1946, note COf, 3rd Law
4.7	2412.8	CH2 (g, triplet) → C (g) + 2 H (g)	Δ_rH°(0 K) = 179.76 ± 0.07 kcal/mol	Feller 2014
3.9	2430.1	CH3 (g) → CH2 (g, triplet) + H (g)	Δ_rH°(0 K) = 109.26 ± 0.08 kcal/mol	Feller 2016, est unc, note unc2
2.3	2375.1	2 H2 (g) + C (graphite) → CH4 (g)	Δ_rG°(1165 K) = 37.521 ± 0.068 kJ/mol	Smith 1946, note COf, 3rd Law
2.2	2454.8	CH2 (g, triplet) → CH (g) + H (g)	Δ_rH°(0 K) = 418.04 ± 0.35 kJ/mol	Csaszar 2003
2.0	2455.5	CH2 (g, singlet) → CH (g) + H (g)	Δ_rH°(0 K) = 90.97 ± 0.12 kcal/mol	Feller 2014
1.5	2414.9	CH2 (g, singlet) → C (g) + 2 H (g)	Δ_rH°(0 K) = 170.98 ± 0.11 (×1.445) kcal/mol	Feller 2014
1.4	2959.1	CH3OH (g) → CH2 (g, singlet) + H2O (g)	Δ_rH°(0 K) = 90.84 ± 0.17 kcal/mol	Nguyen 2015a
1.4	2429.8	CH3 (g) → CH2 (g, triplet) + H (g)	Δ_rH°(0 K) = 457.05 ± 0.56 kJ/mol	Harding 2008
1.3	2427.1	CH3 (g) → [CH2]+ (g) + H (g)	Δ_rH°(0 K) = 15.120 ± 0.006 eV	Litorja 1998
1.2	2411.9	CH2 (g, triplet) → C (g) + 2 H (g)	Δ_rH°(0 K) = 752.45 ± 0.56 kJ/mol	Harding 2008
1.2	2424.4	CH2 (g, triplet) → CH2 (g, singlet)	Δ_rH°(0 K) = 3156 ± 15 cm-1	Bunker 1986, note CH2
1.1	2429.4	CH3 (g) → CH2 (g, triplet) + H (g)	Δ_rH°(0 K) = 109.22 ± 0.15 kcal/mol	Karton 2008
1.1	2228.7	C (graphite) + O2 (g) → CO2 (g)	Δ_rH°(298.15 K) = -393.464 ± 0.024 kJ/mol	Hawtin 1966, note CO2e
1.0	2434.1	[CH2]- (g) → C- (g) + 2 H (g)	Δ_rH°(0 K) = 165.69 ± 0.12 kcal/mol	Feller 2016, note unc2
1.0	2411.5	CH2 (g, triplet) → C (g) + 2 H (g)	Δ_rH°(0 K) = 179.86 ± 0.15 kcal/mol	Karton 2008
0.9	2414.7	CH2 (g, singlet) → C (g) + 2 H (g)	Δ_rH°(0 K) = 170.80 ± 0.2 kcal/mol	Feller 2008
0.9	2412.1	CH2 (g, triplet) → C (g) + 2 H (g)	Δ_rH°(0 K) = 753.03 ± 0.62 (×1.044) kJ/mol	Csaszar 2003

Top 10 species with enthalpies of formation correlated to the Δ_fH° of CH2CO (g, para singlet)

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	Ketene	CH2CO (g)	-45.34	-48.40	± 0.11	kJ/mol	42.0367 ± 0.0016	463-51-4*0
100.0	Ketene	CH2CO (g, ortho singlet)	-45.22	-48.40	± 0.11	kJ/mol	42.0367 ± 0.0016	463-51-4*22
100.0	Ketene	CH2CO (g, singlet)	-45.34	-48.40	± 0.11	kJ/mol	42.0367 ± 0.0016	463-51-4*2
99.7	Ketene cation	[CH2CO]+ (g)	882.23	879.06	± 0.11	kJ/mol	42.0361 ± 0.0016	64999-16-2*0
97.1	Methylene	CH2 (g, singlet)	428.73	429.14	± 0.11	kJ/mol	14.02658 ± 0.00081	2465-56-7*2
84.4	Methylene	CH2 (g)	391.066	391.612	± 0.093	kJ/mol	14.02658 ± 0.00081	2465-56-7*0
84.4	Methylene	CH2 (g, triplet)	391.066	391.612	± 0.093	kJ/mol	14.02658 ± 0.00081	2465-56-7*1
78.9	Methyliumyl	[CH2]+ (g)	1393.200	1394.059	± 0.099	kJ/mol	14.02603 ± 0.00081	15091-72-2*0
38.3	Carbon	C (g)	711.381	716.866	± 0.039	kJ/mol	12.01070 ± 0.00080	7440-44-0*0
38.3	Carbon	C (g, triplet)	711.381	716.866	± 0.039	kJ/mol	12.01070 ± 0.00080	7440-44-0*1

Most Influential reactions involving CH2CO (g, para singlet)

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	4363.1	CH2CO (g, para singlet) → CH2CO (g)	Δ_rH°(0 K) = 0 ± 0 cm-1	triv
1.000	4364.1	CH2CO (g, para singlet) → CH2CO (g, ortho singlet)	Δ_rH°(0 K) = 9.7398 ± 0.0005 cm-1	Johns 1992, Brown 1990, Kwiatkowski 1995

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.