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].

Formyloxidanyl

Formula: HC(O)O (g, 2B2)

CAS RN: 16499-21-1

ATcT ID: 16499-21-1*2

SMILES: C(=O)[O]

InChI: InChI=1S/CHO2/c2-1-3/h1H

InChIKey: JRCLCXAVSVCEQC-UHFFFAOYSA-N

Hills Formula: C1H1O2

2D Image:

Aliases: HC(O)O; Formyloxidanyl; Formyloxy; Oxomethoxy; Formyloxyl; Formate free radical; HCO2

Relative Molecular Mass: 45.0174 ± 0.0010

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
-121.96	-125.31	± 0.55	kJ/mol

3D Image of HC(O)O (g, 2B2)

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Top contributors to the provenance of Δ_fH° of HC(O)O (g, 2B2)

The 20 contributors listed below account only for 48.3% of the provenance of Δ_fH° of HC(O)O (g, 2B2).
A total of 103 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
6.7	4919.7	HOCO (g, cis) → HC(O)O (g, 2A1)	Δ_rH°(0 K) = 11.6 ± 0.4 kcal/mol	Feller 2003c
5.1	4922.1	HC(O)OH (g) + Cl- (g) → [HC(O)O]- (g) + HCl (g)	Δ_rG°(600 K) = 8.4 ± 0.2 (×2.65) kcal/mol	Cumming 1978
5.0	7184.1	[C6H5O]- (g) + HC(O)OH (g) → C6H5OH (g) + [HC(O)O]- (g)	Δ_rG°(500 K) = -4.9 ± 0.4 kcal/mol	Cumming 1978
3.6	4918.8	HOCO (g, trans) → HC(O)O (g, 2A1)	Δ_rH°(0 K) = 13.8 ± 0.5 (×1.139) kcal/mol	Dixon 2003, est unc
3.3	4932.4	HC(O)O (g, 2A1) → H (g) + CO2 (g)	Δ_rH°(0 K) = -12.6 ± 0.7 kcal/mol	Feller 2003c, note unc3
3.1	4907.9	HC(O)O (g, 2A1) → H (g) + C (g) + 2 O (g)	Δ_rH°(0 K) = 369.0 ± 0.4 (×1.795) kcal/mol	Feller 2003c
2.5	4907.7	HC(O)O (g, 2A1) → H (g) + C (g) + 2 O (g)	Δ_rH°(0 K) = 369.2 ± 0.8 kcal/mol	Dixon 2003, est unc
2.5	4914.9	[HC(O)O]- (g) → H (g) + C (g) + 2 O (g)	Δ_rH°(0 K) = 450.2 ± 0.8 kcal/mol	Dixon 2003, est unc
2.2	4929.5	HC(O)OH (g) + [OH]- (g) → [HC(O)O]- (g) + H2O (g)	Δ_rH°(0 K) = -46.33 ± 0.8 kcal/mol	Ruscic W1RO
2.0	4926.5	HC(O)OH (g, syn) → HC(O)O (g, 2A1) + H (g)	Δ_rH°(0 K) = 111.1 ± 0.6 (×1.414) kcal/mol	Feller 2003c
1.7	4928.5	HC(O)OH (g) → [HC(O)O]- (g) + H+ (g)	Δ_rH°(0 K) = 343.23 ± 0.90 kcal/mol	Ruscic W1RO
1.4	5291.5	[CH3C(O)O]- (g) + HC(O)OH (g, syn) → CH3C(O)OH (g, syn) + [HC(O)O]- (g)	Δ_rH°(0 K) = -3.73 ± 0.8 kcal/mol	Ruscic W1RO
1.4	4929.2	HC(O)OH (g) + [OH]- (g) → [HC(O)O]- (g) + H2O (g)	Δ_rH°(0 K) = -45.77 ± 1.0 kcal/mol	Ruscic G4
1.4	4929.4	HC(O)OH (g) + [OH]- (g) → [HC(O)O]- (g) + H2O (g)	Δ_rH°(0 K) = -46.27 ± 1.0 kcal/mol	Ruscic CBS-n
1.2	7184.6	[C6H5O]- (g) + HC(O)OH (g) → C6H5OH (g) + [HC(O)O]- (g)	Δ_rH°(0 K) = -5.30 ± 0.8 kcal/mol	Ruscic W1RO
0.9	5291.2	[CH3C(O)O]- (g) + HC(O)OH (g, syn) → CH3C(O)OH (g, syn) + [HC(O)O]- (g)	Δ_rH°(0 K) = -3.76 ± 1.0 kcal/mol	Ruscic G4
0.9	5291.4	[CH3C(O)O]- (g) + HC(O)OH (g, syn) → CH3C(O)OH (g, syn) + [HC(O)O]- (g)	Δ_rH°(0 K) = -3.54 ± 1.0 kcal/mol	Ruscic CBS-n
0.9	4933.1	HC(O)O (g, 2B2) → H (g) + CO2 (g)	Δ_rH°(0 K) = -14.5 ± 0.7 (×1.915) kcal/mol	Feller 2003c, note unc3
0.8	4908.8	HC(O)O (g, 2B2) → H (g) + C (g) + 2 O (g)	Δ_rH°(0 K) = 367.4 ± 0.8 (×1.756) kcal/mol	Dixon 2003, est unc
0.8	4918.5	HOCO (g, trans) → HC(O)O (g, 2A1)	Δ_rH°(0 K) = 13.49 ± 1.2 kcal/mol	Ruscic W1RO

Top 10 species with enthalpies of formation correlated to the Δ_fH° of HC(O)O (g, 2B2)

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
99.1	Formyloxidanyl	HC(O)O (g, 2A1)	-125.77	-127.43	± 0.55	kJ/mol	45.0174 ± 0.0010	16499-21-1*1
99.1	Formyloxidanyl	HC(O)O (g)	-125.77	-127.13	± 0.55	kJ/mol	45.0174 ± 0.0010	16499-21-1*0
99.0	Formate	[HC(O)O]- (g)	-463.10	-466.75	± 0.55	kJ/mol	45.0180 ± 0.0010	71-47-6*0
23.7	Formyloxoniumylidene	[HC(O)O]+ (g)	1017.4	1014.0	± 1.4	kJ/mol	45.0169 ± 0.0010	54375-27-8*0
21.5	Hydroxyformyl	HOCO (g, cis)	-174.34	-177.37	± 0.48	kJ/mol	45.0174 ± 0.0010	2564-86-5*2
20.9	Hydroxyformyl	HOCO (g)	-181.15	-183.70	± 0.40	kJ/mol	45.0174 ± 0.0010	2564-86-5*0
20.9	Hydroxyformyl	HOCO (g, trans)	-181.15	-184.12	± 0.40	kJ/mol	45.0174 ± 0.0010	2564-86-5*1
17.6	Formic acid	HC(O)OH (g)	-371.03	-378.33	± 0.21	kJ/mol	46.0254 ± 0.0010	64-18-6*0
17.6	Formic acid	HC(O)OH (g, syn)	-371.03	-378.35	± 0.21	kJ/mol	46.0254 ± 0.0010	64-18-6*1
16.0	Hydroxyformyl anion	[HOCO]- (g, trans)	-313.64	-315.45	± 0.56	kJ/mol	45.0180 ± 0.0010	78944-70-4*1

Most Influential reactions involving HC(O)O (g, 2B2)

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
0.630	4912.1	[HC(O)O]- (g) → HC(O)O (g, 2B2)	Δ_rH°(0 K) = 28516 ± 8 cm-1	Garand 2010
0.532	4917.1	HC(O)O (g, 2A1) → HC(O)O (g, 2B2)	Δ_rH°(0 K) = 318 ± 8 cm-1	Garand 2010
0.118	4910.6	HC(O)O (g, 2B2) → [HC(O)O]+ (g)	Δ_rH°(0 K) = 11.787 ± 0.040 eV	Ruscic W1RO
0.085	4917.11	HC(O)O (g, 2A1) → HC(O)O (g, 2B2)	Δ_rH°(0 K) = 310.2 ± 20 cm-1	Garand 2010, est unc
0.054	4917.13	HC(O)O (g, 2A1) → HC(O)O (g, 2B2)	Δ_rH°(0 K) = 327 ± 25 cm-1	Klein 2011, est unc
0.054	4917.12	HC(O)O (g, 2A1) → HC(O)O (g, 2B2)	Δ_rH°(0 K) = 325.8 ± 25 cm-1	Zou 2015, est unc
0.035	4910.4	HC(O)O (g, 2B2) → [HC(O)O]+ (g)	Δ_rH°(0 K) = 11.785 ± 0.073 eV	Ruscic G4
0.021	4910.3	HC(O)O (g, 2B2) → [HC(O)O]+ (g)	Δ_rH°(0 K) = 11.805 ± 0.093 eV	Ruscic G3X
0.019	4910.5	HC(O)O (g, 2B2) → [HC(O)O]+ (g)	Δ_rH°(0 K) = 11.825 ± 0.099 eV	Ruscic CBS-n
0.009	4933.1	HC(O)O (g, 2B2) → H (g) + CO2 (g)	Δ_rH°(0 K) = -14.5 ± 0.7 (×1.915) kcal/mol	Feller 2003c, note unc3
0.008	4908.8	HC(O)O (g, 2B2) → H (g) + C (g) + 2 O (g)	Δ_rH°(0 K) = 367.4 ± 0.8 (×1.756) kcal/mol	Dixon 2003, est unc
0.007	4927.4	HC(O)OH (g, syn) → HC(O)O (g, 2B2) + H (g)	Δ_rH°(0 K) = 112.53 ± 1.50 kcal/mol	Ruscic W1RO
0.007	4908.6	HC(O)O (g, 2B2) → H (g) + C (g) + 2 O (g)	Δ_rH°(0 K) = 368.00 ± 1.50 kcal/mol	Ruscic W1RO
0.006	4927.3	HC(O)OH (g, syn) → HC(O)O (g, 2B2) + H (g)	Δ_rH°(0 K) = 111.03 ± 1.60 kcal/mol	Ruscic G4
0.006	4908.7	HC(O)O (g, 2B2) → H (g) + C (g) + 2 O (g)	Δ_rH°(0 K) = 368.02 ± 1.6 kcal/mol	Haworth 2000, est unc
0.006	4908.4	HC(O)O (g, 2B2) → H (g) + C (g) + 2 O (g)	Δ_rH°(0 K) = 369.00 ± 1.60 kcal/mol	Ruscic G4
0.005	4908.9	HC(O)O (g, 2B2) → H (g) + C (g) + 2 O (g)	Δ_rH°(0 K) = 367.1 ± 0.4 (×4.269) kcal/mol	Feller 2003c
0.005	4927.2	HC(O)OH (g, syn) → HC(O)O (g, 2B2) + H (g)	Δ_rH°(0 K) = 111.02 ± 1.72 kcal/mol	Ruscic G3X
0.005	4908.3	HC(O)O (g, 2B2) → H (g) + C (g) + 2 O (g)	Δ_rH°(0 K) = 369.42 ± 1.72 kcal/mol	Ruscic G3X
0.005	4927.5	HC(O)OH (g, syn) → HC(O)O (g, 2B2) + H (g)	Δ_rH°(0 K) = 113.0 ± 0.6 (×3.084) kcal/mol	Feller 2003c

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.