Selected ATcT [1, 2] enthalpy of formation based on version 1.148 of the Thermochemical Network [3]

This version of ATcT results[3] was generated by additional expansion of version 1.140 to include species relevant to a recent study of the role of atmospheric methanediol[4].

Oxoethylidene

Formula: HCC(O)H (g, singlet)

CAS RN: 39920-84-8

ATcT ID: 39920-84-8*2

SMILES: [CH]C=O

InChI: InChI=1S/C2H2O/c1-2-3/h1-2H

InChIKey: UBXLAXBUHBLQHZ-UHFFFAOYSA-N

Hills Formula: C2H2O1

2D Image:

Aliases: HCC(O)H; Oxoethylidene; Formylcarbene; Formylmethylene; CHC(O)H; CHCHO; HCCHO; C(O)HCH; HC(O)CH

Relative Molecular Mass: 42.0367 ± 0.0016

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
275.5	272.6	± 1.7	kJ/mol

3D Image of HCC(O)H (g, singlet)

spin ON spin OFF

Top contributors to the provenance of Δ_fH° of HCC(O)H (g, singlet)

The 16 contributors listed below account for 90.1% of the provenance of Δ_fH° of HCC(O)H (g, singlet).

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
12.3	4345.1	2 CH4 (g) + H2O (g) → HCC(O)H (g, syn-triplet) + 4 H2 (g)	Δ_rH°(0 K) = 633.00 ± 1.5 kJ/mol	Klippenstein 2017
9.4	4348.4	HCC(O)H (g, triplet) + CH2 (g, singlet) → HCC(O)H (g, singlet) + CH2 (g, triplet)	Δ_rH°(0 K) = -5.57 ± 0.9 kcal/mol	Ruscic W1RO
7.6	4348.2	HCC(O)H (g, triplet) + CH2 (g, singlet) → HCC(O)H (g, singlet) + CH2 (g, triplet)	Δ_rH°(0 K) = -5.19 ± 1.0 kcal/mol	Ruscic G4
7.2	4336.5	HCC(O)H (g, singlet) → 2 C (g) + 2 H (g) + O (g)	Δ_rH°(0 K) = 436.04 ± 1.50 kcal/mol	Ruscic W1RO
6.3	4336.3	HCC(O)H (g, singlet) → 2 C (g) + 2 H (g) + O (g)	Δ_rH°(0 K) = 436.72 ± 1.60 kcal/mol	Ruscic G4
5.7	4348.1	HCC(O)H (g, triplet) + CH2 (g, singlet) → HCC(O)H (g, singlet) + CH2 (g, triplet)	Δ_rH°(0 K) = -6.71 ± 1.1 (×1.044) kcal/mol	Ruscic G3X
5.4	4336.2	HCC(O)H (g, singlet) → 2 C (g) + 2 H (g) + O (g)	Δ_rH°(0 K) = 437.98 ± 1.72 kcal/mol	Ruscic G3X
5.3	4347.5	HCC(O)H (g, syn-triplet) → HCC(O)H (g, singlet)	Δ_rH°(0 K) = 1264 ± 420 cm-1	Ruscic W1RO
4.6	4347.3	HCC(O)H (g, syn-triplet) → HCC(O)H (g, singlet)	Δ_rH°(0 K) = 1194 ± 450 cm-1	Ruscic G4
4.6	4347.6	HCC(O)H (g, syn-triplet) → HCC(O)H (g, singlet)	Δ_rH°(0 K) = 1099 ± 450 cm-1	Girard 2003, est unc, Ruscic G3B3
4.4	4351.6	HCC(O)H (g, singlet) → CH2CO (g)	Δ_rH°(0 K) = -327.5 ± 8 kJ/mol	Scott 1994
3.9	4348.3	HCC(O)H (g, triplet) + CH2 (g, singlet) → HCC(O)H (g, singlet) + CH2 (g, triplet)	Δ_rH°(0 K) = -4.18 ± 1.3 (×1.067) kcal/mol	Ruscic CBS-n
3.8	4347.2	HCC(O)H (g, syn-triplet) → HCC(O)H (g, singlet)	Δ_rH°(0 K) = 922 ± 490 cm-1	Ruscic G3X
3.4	4336.4	HCC(O)H (g, singlet) → 2 C (g) + 2 H (g) + O (g)	Δ_rH°(0 K) = 436.01 ± 2.16 kcal/mol	Ruscic CBS-n
2.9	4347.4	HCC(O)H (g, syn-triplet) → HCC(O)H (g, singlet)	Δ_rH°(0 K) = 1283 ± 560 cm-1	Ruscic CBS-n
2.5	4351.7	HCC(O)H (g, singlet) → CH2CO (g)	Δ_rH°(0 K) = -76.70 ± 2.5 kcal/mol	Girard 2003, est unc, Scott 1994

Top 10 species with enthalpies of formation correlated to the Δ_fH° of HCC(O)H (g, 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
49.4	Oxoethylidene	HCC(O)H (g, triplet)	261.1	258.3	± 1.1	kJ/mol	42.0367 ± 0.0016	39920-84-8*1
49.4	Oxoethylidene	HCC(O)H (g, syn-triplet)	261.1	257.6	± 1.1	kJ/mol	42.0367 ± 0.0016	39920-84-8*12
49.4	Oxoethylidene	HCC(O)H (g)	261.1	258.3	± 1.1	kJ/mol	42.0367 ± 0.0016	39920-84-8*0
28.3	Oxoethylidene	HCC(O)H (g, anti-triplet)	265.9	262.6	± 1.6	kJ/mol	42.0367 ± 0.0016	39920-84-8*11
22.7	Oxoethylidene anion	[HCC(O)H]- (g)	86.9	84.2	± 2.1	kJ/mol	42.0372 ± 0.0016	106543-38-8*0
22.7	Oxoethylidene anion	[HCC(O)H]- (g, anti-gauche)	86.9	83.6	± 2.1	kJ/mol	42.0372 ± 0.0016	106543-38-8*1
21.4	Oxoethylidene anion	[HCC(O)H]- (g, syn-gauche)	92.3	89.0	± 2.3	kJ/mol	42.0372 ± 0.0016	106543-38-8*2
20.6	2-Oxo-1-ethylium-1-yl	[HCC(O)H]+ (g, syn-quartet)	1292.1	1288.7	± 2.4	kJ/mol	42.0361 ± 0.0016	214464-96-7*12
19.7	2-Oxo-1-ethylium-1-yl	[HCC(O)H]+ (g, anti-quartet)	1289.4	1286.0	± 2.5	kJ/mol	42.0361 ± 0.0016	214464-96-7*11
19.7	2-Oxo-1-ethylium-1-yl	[HCC(O)H]+ (g, quartet)	1289.4	1286.8	± 2.5	kJ/mol	42.0361 ± 0.0016	214464-96-7*1

Most Influential reactions involving HCC(O)H (g, 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
0.155	4348.4	HCC(O)H (g, triplet) + CH2 (g, singlet) → HCC(O)H (g, singlet) + CH2 (g, triplet)	Δ_rH°(0 K) = -5.57 ± 0.9 kcal/mol	Ruscic W1RO
0.126	4348.2	HCC(O)H (g, triplet) + CH2 (g, singlet) → HCC(O)H (g, singlet) + CH2 (g, triplet)	Δ_rH°(0 K) = -5.19 ± 1.0 kcal/mol	Ruscic G4
0.095	4348.1	HCC(O)H (g, triplet) + CH2 (g, singlet) → HCC(O)H (g, singlet) + CH2 (g, triplet)	Δ_rH°(0 K) = -6.71 ± 1.1 (×1.044) kcal/mol	Ruscic G3X
0.087	4347.5	HCC(O)H (g, syn-triplet) → HCC(O)H (g, singlet)	Δ_rH°(0 K) = 1264 ± 420 cm-1	Ruscic W1RO
0.076	4347.6	HCC(O)H (g, syn-triplet) → HCC(O)H (g, singlet)	Δ_rH°(0 K) = 1099 ± 450 cm-1	Girard 2003, est unc, Ruscic G3B3
0.076	4347.3	HCC(O)H (g, syn-triplet) → HCC(O)H (g, singlet)	Δ_rH°(0 K) = 1194 ± 450 cm-1	Ruscic G4
0.072	4336.5	HCC(O)H (g, singlet) → 2 C (g) + 2 H (g) + O (g)	Δ_rH°(0 K) = 436.04 ± 1.50 kcal/mol	Ruscic W1RO
0.065	4348.3	HCC(O)H (g, triplet) + CH2 (g, singlet) → HCC(O)H (g, singlet) + CH2 (g, triplet)	Δ_rH°(0 K) = -4.18 ± 1.3 (×1.067) kcal/mol	Ruscic CBS-n
0.064	4347.2	HCC(O)H (g, syn-triplet) → HCC(O)H (g, singlet)	Δ_rH°(0 K) = 922 ± 490 cm-1	Ruscic G3X
0.063	4336.3	HCC(O)H (g, singlet) → 2 C (g) + 2 H (g) + O (g)	Δ_rH°(0 K) = 436.72 ± 1.60 kcal/mol	Ruscic G4
0.055	4336.2	HCC(O)H (g, singlet) → 2 C (g) + 2 H (g) + O (g)	Δ_rH°(0 K) = 437.98 ± 1.72 kcal/mol	Ruscic G3X
0.049	4347.4	HCC(O)H (g, syn-triplet) → HCC(O)H (g, singlet)	Δ_rH°(0 K) = 1283 ± 560 cm-1	Ruscic CBS-n
0.044	4351.6	HCC(O)H (g, singlet) → CH2CO (g)	Δ_rH°(0 K) = -327.5 ± 8 kJ/mol	Scott 1994
0.034	4336.4	HCC(O)H (g, singlet) → 2 C (g) + 2 H (g) + O (g)	Δ_rH°(0 K) = 436.01 ± 2.16 kcal/mol	Ruscic CBS-n
0.026	4351.7	HCC(O)H (g, singlet) → CH2CO (g)	Δ_rH°(0 K) = -76.70 ± 2.5 kcal/mol	Girard 2003, est unc, Scott 1994

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. 1.148 of the Thermochemical Network (2023); available at ATcT.anl.gov
4		T. L. Nguyen, J. Peeters, J.-F. Müller, A. Perera, D. H. Bross, B. Ruscic, and J. F. Stanton, Methanediol from Cloud-Processed Formaldehyde is Only a Minor Source of Atmospheric Formic Acid Natl. Acad. Sci. 120, e2304650120/1-8 (2023) [DOI: 10.1073/pnas.2304650120]
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.