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].

Isobutene

Formula: CH2C(CH3)2 (g)

CAS RN: 115-11-7

ATcT ID: 115-11-7*0

SMILES: CC(=C)C

InChI: InChI=1S/C4H8/c1-4(2)3/h1H2,2-3H3

InChIKey: VQTUBCCKSQIDNK-UHFFFAOYSA-N

Hills Formula: C4H8

2D Image:

Aliases: CH2C(CH3)2; Isobutene; 2-Methyl-1-propene; gamma-Butylene; 1,1-Dimethylethene; 1,1-Dimethylethylene; 2-Methyl-2-propene; 2-Methylpropene; 2-Methylpropylene; i-Butene; iso-Butene; Isobutylene; Isopropylidenemethylene; i-C4H8; (CH3)2CCH2; CH2=C(CH3)2; (CH3)2C=CH2

Relative Molecular Mass: 56.1063 ± 0.0032

Δ_fH°(0 K)	Δ_fH°(298.15 K)	Uncertainty	Units
4.29	-16.77	± 0.32	kJ/mol

3D Image of CH2C(CH3)2 (g)

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Top contributors to the provenance of Δ_fH° of CH2C(CH3)2 (g)

The 20 contributors listed below account only for 62.3% of the provenance of Δ_fH° of CH2C(CH3)2 (g).
A total of 232 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
24.6	3761.1	CH2C(CH3)2 (g) + H2 (g) → CH(CH3)3 (g)	Δ_rH°(355.15 K) = -28.411 ± 0.060 kcal/mol	Kistiakowsky 1935a
7.0	3760.1	CH2C(CH3)2 (g) + 6 O2 (g) → 4 CO2 (g) + 4 H2O (cr,l)	Δ_rH°(298.15 K) = -645.18 ± 0.25 kcal/mol	Prosen 1951
6.2	3700.1	CH(CH3)3 (g) + 13/2 O2 (g) → 4 CO2 (g) + 5 H2O (cr,l)	Δ_rH°(298.15 K) = -2868.98 ± 0.59 kJ/mol	Pittam 1972
2.6	3700.2	CH(CH3)3 (g) + 13/2 O2 (g) → 4 CO2 (g) + 5 H2O (cr,l)	Δ_rH°(298.15 K) = -685.36 ± 0.11 (×1.957) kcal/mol	Prosen 1951
2.3	3702.2	CH(CH3)3 (g) → CH3CH2CH2CH3 (g)	Δ_rH°(298.15 K) = 8.59 ± 0.79 kJ/mol	Prosen 1951
2.2	125.2	1/2 O2 (g) + H2 (g) → H2O (cr,l)	Δ_rH°(298.15 K) = -285.8261 ± 0.040 kJ/mol	Rossini 1939, Rossini 1931, Rossini 1931b, note H2Oa, Rossini 1930
2.0	3702.5	CH(CH3)3 (g) → CH3CH2CH2CH3 (g)	Δ_rH°(380 K) = 2.32 ± 0.20 kcal/mol	Pines 1945, 2nd Law
1.9	3702.1	CH(CH3)3 (g) → CH3CH2CH2CH3 (g)	Δ_rH°(298.15 K) = 8.54 ± 0.86 kJ/mol	Pittam 1972
1.9	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
1.8	3759.1	4 CH4 (g) → CH2C(CH3)2 (g) + 4 H2 (g)	Δ_rH°(0 K) = 270.66 ± 2.00 kJ/mol	Klippenstein 2017
1.4	3769.6	CH3CHCHCH3 (g, trans) → CH2C(CH3)2 (g)	Δ_rH°(0 K) = -5.11 ± 2.00 kJ/mol	Klippenstein 2017
1.4	3702.6	CH(CH3)3 (g) → CH3CH2CH2CH3 (g)	Δ_rG°(380 K) = 0.70 ± 0.24 kcal/mol	Pines 1945, 3rd Law
1.4	3785.6	CH2CHCH2CH3 (g) → CH2C(CH3)2 (g)	Δ_rH°(0 K) = -16.85 ± 2.00 kJ/mol	Klippenstein 2017
0.9	3931.1	CH3CH2CH(CH3)2 (g) + CH3CH2CH3 (g) → CH(CH3)3 (g) + CH3CH2CH2CH3 (g)	Δ_rH°(298.15 K) = -0.48 ± 0.31 kcal/mol	Prosen 1945
0.9	3758.6	CH2C(CH3)2 (g) → 4 C (g) + 8 H (g)	Δ_rH°(0 K) = 1091.9 ± 0.7 kcal/mol	Bakowies 2020
0.7	2228.7	C (graphite) + O2 (g) → CO2 (g)	Δ_rH°(298.15 K) = -393.464 ± 0.024 kJ/mol	Hawtin 1966, note CO2e
0.6	3762.6	CH2C(CH3)2 (g) + CH2CH2 (g) → 2 CH3CHCH2 (g)	Δ_rH°(0 K) = 1.1 ± 0.7 kcal/mol	Bakowies 2020
0.5	3699.1	4 CH4 (g) → CH(CH3)3 (g) + 3 H2 (g)	Δ_rH°(0 K) = 160.33 ± 2.00 kJ/mol	Klippenstein 2017
0.5	8986.6	CH2C(CH3)2 (g) → CH3C(CH3)CH (g) + H (g)	Δ_rH°(0 K) = 463.81 ± 2.0 kJ/mol	Klippenstein 2017
0.5	3701.8	CH(CH3)3 (g) → CH3CH2CH2CH3 (g)	Δ_rH°(0 K) = 1.68 ± 0.40 kcal/mol	Karton 2009b

Top 10 species with enthalpies of formation correlated to the Δ_fH° of CH2C(CH3)2 (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
70.8	iso-Butane	CH(CH3)3 (g)	-105.89	-134.49	± 0.27	kJ/mol	58.1222 ± 0.0033	75-28-5*0
36.9	n-Butane	CH3CH2CH2CH3 (g)	-98.25	-125.56	± 0.18	kJ/mol	58.1222 ± 0.0033	106-97-8*0
32.2	Propane	CH3CH2CH3 (g)	-82.73	-105.01	± 0.15	kJ/mol	44.0956 ± 0.0025	74-98-6*0
29.9	Carbonic acid	C(O)(OH)2 (aq, undissoc)		-698.673	± 0.028	kJ/mol	62.0248 ± 0.0012	463-79-6*1000
27.7	Water	H2O (cr, l, eq.press.)	-286.278	-285.806	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*499
27.7	Water	H2O (l, eq.press.)		-285.806	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*589
27.7	Oxonium	[H3O]+ (aq)		-285.804	± 0.022	kJ/mol	19.02267 ± 0.00037	13968-08-6*800
27.7	Water	H2O (l)		-285.804	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*590
27.7	Water	H2O (cr,l)	-286.276	-285.804	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*500
27.7	Water	H2O (g)	-238.907	-241.810	± 0.022	kJ/mol	18.01528 ± 0.00033	7732-18-5*0

Most Influential reactions involving CH2C(CH3)2 (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
0.792	3761.1	CH2C(CH3)2 (g) + H2 (g) → CH(CH3)3 (g)	Δ_rH°(355.15 K) = -28.411 ± 0.060 kcal/mol	Kistiakowsky 1935a
0.154	8987.6	CH3C(CH3)CH (g) + CH3CHCH2 (g) → CH2C(CH3)2 (g) + CH3CHCH (g, cis)	Δ_rH°(0 K) = -3.83 ± 2.0 kJ/mol	Klippenstein 2017
0.127	8986.6	CH2C(CH3)2 (g) → CH3C(CH3)CH (g) + H (g)	Δ_rH°(0 K) = 463.81 ± 2.0 kJ/mol	Klippenstein 2017
0.096	7667.5	CH3C(CO)CH3 (g) + CH2CCH2 (g) → CH2CCO (g) + CH2C(CH3)2 (g)	Δ_rH°(0 K) = 3.01 ± 0.85 kcal/mol	Ruscic W1RO
0.094	7668.5	CH3C(CO)CH3 (g) + CH2CH2 (g) → CH2CO (g) + CH2C(CH3)2 (g)	Δ_rH°(0 K) = -7.17 ± 0.85 kcal/mol	Ruscic W1RO
0.085	7667.4	CH3C(CO)CH3 (g) + CH2CCH2 (g) → CH2CCO (g) + CH2C(CH3)2 (g)	Δ_rH°(0 K) = 2.85 ± 0.90 kcal/mol	Ruscic CBS-n
0.085	7667.1	CH3C(CO)CH3 (g) + CH2CCH2 (g) → CH2CCO (g) + CH2C(CH3)2 (g)	Δ_rH°(0 K) = 2.87 ± 0.90 kcal/mol	Ruscic G3X
0.085	7667.2	CH3C(CO)CH3 (g) + CH2CCH2 (g) → CH2CCO (g) + CH2C(CH3)2 (g)	Δ_rH°(0 K) = 2.85 ± 0.90 kcal/mol	Ruscic G4
0.084	7668.1	CH3C(CO)CH3 (g) + CH2CH2 (g) → CH2CO (g) + CH2C(CH3)2 (g)	Δ_rH°(0 K) = -6.75 ± 0.90 kcal/mol	Ruscic G3X
0.084	7668.2	CH3C(CO)CH3 (g) + CH2CH2 (g) → CH2CO (g) + CH2C(CH3)2 (g)	Δ_rH°(0 K) = -6.86 ± 0.90 kcal/mol	Ruscic G4
0.084	7668.4	CH3C(CO)CH3 (g) + CH2CH2 (g) → CH2CO (g) + CH2C(CH3)2 (g)	Δ_rH°(0 K) = -6.85 ± 0.90 kcal/mol	Ruscic CBS-n
0.079	3760.1	CH2C(CH3)2 (g) + 6 O2 (g) → 4 CO2 (g) + 4 H2O (cr,l)	Δ_rH°(298.15 K) = -645.18 ± 0.25 kcal/mol	Prosen 1951
0.073	7652.5	CH3C(O)CHCH2 (g, trans) + CH2C(CH3)2 (g) → CH3C(O)CH3 (g) + CH2C(CH3)CHCH2 (g)	Δ_rH°(0 K) = -2.95 ± 0.85 kcal/mol	Ruscic W1RO
0.069	7667.3	CH3C(CO)CH3 (g) + CH2CCH2 (g) → CH2CCO (g) + CH2C(CH3)2 (g)	Δ_rH°(0 K) = 3.21 ± 1.00 kcal/mol	Ruscic CBS-n
0.068	7668.3	CH3C(CO)CH3 (g) + CH2CH2 (g) → CH2CO (g) + CH2C(CH3)2 (g)	Δ_rH°(0 K) = -6.48 ± 1.00 kcal/mol	Ruscic CBS-n
0.065	7652.2	CH3C(O)CHCH2 (g, trans) + CH2C(CH3)2 (g) → CH3C(O)CH3 (g) + CH2C(CH3)CHCH2 (g)	Δ_rH°(0 K) = -2.96 ± 0.90 kcal/mol	Ruscic G4
0.065	7652.1	CH3C(O)CHCH2 (g, trans) + CH2C(CH3)2 (g) → CH3C(O)CH3 (g) + CH2C(CH3)CHCH2 (g)	Δ_rH°(0 K) = -2.87 ± 0.90 kcal/mol	Ruscic G3X
0.065	7652.4	CH3C(O)CHCH2 (g, trans) + CH2C(CH3)2 (g) → CH3C(O)CH3 (g) + CH2C(CH3)CHCH2 (g)	Δ_rH°(0 K) = -2.95 ± 0.90 kcal/mol	Ruscic CBS-n
0.053	7652.3	CH3C(O)CHCH2 (g, trans) + CH2C(CH3)2 (g) → CH3C(O)CH3 (g) + CH2C(CH3)CHCH2 (g)	Δ_rH°(0 K) = -2.86 ± 1.0 kcal/mol	Ruscic CBS-n
0.049	8951.5	CH3C(CH2)CH2 (g) + CH3CHCH2 (g) → CH2C(CH3)2 (g) + CH2CHCH2 (g)	Δ_rH°(0 K) = -1.62 ± 0.85 kcal/mol	Ruscic W1RO

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.