Butane, 2-methyl-

Formula: C₅H₁₂
Molecular weight: 72.1488
IUPAC Standard InChI: InChI=1S/C5H12/c1-4-5(2)3/h5H,4H2,1-3H3
IUPAC Standard InChIKey: QWTDNUCVQCZILF-UHFFFAOYSA-N
CAS Registry Number: 78-78-4
Chemical structure:
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Other names: iso-Pentane; 1,1,2-Trimethylethane; 2-Methylbutane; iso-C5H12; Ethyldimethylmethane; Isoamylhydride; Exxsol isopentane S; 1,1-Dimethylpropane; Methylbutane; NSC 119476
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Gas phase thermochemistry data

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Data compiled as indicated in comments:
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
GT - Glushko Thermocenter, Russian Academy of Sciences, Moscow

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	-153.7 ± 0.59	kJ/mol	Ccb	Good, 1970	ALS
Δ_fH°_gas	-154.1 ± 0.96	kJ/mol	Cm	Pilcher and Chadwick, 1967	ALS
Δ_fH°_gas	-154.5 ± 0.84	kJ/mol	Ccb	Prosen and Rossini, 1945	ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_gas	-3528.4 ± 0.92	kJ/mol	Cm	Pilcher and Chadwick, 1967	Corresponding Δ_fHº_gas = -154.1 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
Δ_cH°_gas	-3528.6 ± 0.63	kJ/mol	Cm	Knowlton and Rossini, 1939	Corresponding Δ_fHº_gas = -153.9 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
Δ_cH°_gas	-3527.6 ± 3.5	kJ/mol	Ccb	Roth and Pahlke, 1936	Reanalyzed by Cox and Pilcher, 1970, Original value = -3529.0 kJ/mol; Corresponding Δ_fHº_gas = -155.0 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS

Constant pressure heat capacity of gas

C_p,gas (J/mol*K)	Temperature (K)	Reference	Comment
84.94	200.	Scott D.W., 1974	Recommended values were obtained from the consistent correlation scheme for alkanes [ Scott D.W., 1974, 2, Scott D.W., 1974]. This approach gives a better agreement with experimental data than the statistical thermodynamics calculations [ Pitzer K.S., 1946, Scott D.W., 1951].; GT
110.37	273.15
118.9 ± 0.4	298.15
119.50	300.
152.88	400.
183.26	500.
210.04	600.
233.05	700.
253.13	800.
270.70	900.
286.19	1000.
299.57	1100.
311.29	1200.
322.17	1300.
330.54	1400.
338.90	1500.

Constant pressure heat capacity of gas

C_p,gas (J/mol*K)	Temperature (K)	Reference	Comment
125.31 ± 0.37	317.20	Scott D.W., 1951	GT
139.12 ± 0.42	358.15
153.64 ± 0.46	402.30
168.36 ± 0.51	449.20
179.62 ± 0.54	487.05

References

Go To: Top, Gas phase thermochemistry data, Notes

Good, 1970
Good, W.D., The enthalpies of combustion and formation of the isomeric pentanes, J. Chem. Thermodyn., 1970, 2, 237-244. [all data]

Pilcher and Chadwick, 1967
Pilcher, G.; Chadwick, J.D.M., Measurements of heats of combustion by flame calorimetry. Part 4.-n-Pentane, isopentane, neopentane, Trans. Faraday Soc., 1967, 63, 2357-2361. [all data]

Prosen and Rossini, 1945
Prosen, E.J.; Rossini, F.D., Heats of combustion and formation of the paraffin hydrocarbons at 25° C, J. Res. NBS, 1945, 263-267. [all data]

Knowlton and Rossini, 1939
Knowlton, J.W.; Rossini, F.D., Heats of combustion of tetramethylmethane and 2-methylbutane, J. Res. NBS, 1939, 22, 415-424. [all data]

Roth and Pahlke, 1936
Roth, W.A.; Pahlke, H., Sekundare eichsubstanz fur verbrennungscalorimeter fur gase und dampfe. Die verbrennungswarme von isopentandampf, Angew. Chem., 1936, 49, 618-619. [all data]

Cox and Pilcher, 1970
Cox, J.D.; Pilcher, G., Thermochemistry of Organic and Organometallic Compounds, Academic Press, New York, 1970, 1-636. [all data]

Scott D.W., 1974
Scott D.W., Chemical Thermodynamic Properties of Hydrocarbons and Related Substances. Properties of the Alkane Hydrocarbons, C1 through C10 in the Ideal Gas State from 0 to 1500 K. U.S. Bureau of Mines, Bulletin 666, 1974. [all data]

Scott D.W., 1974, 2
Scott D.W., Correlation of the chemical thermodynamic properties of alkane hydrocarbons, J. Chem. Phys., 1974, 60, 3144-3165. [all data]

Pitzer K.S., 1946
Pitzer K.S., The entropies and related properties of branched paraffin hydrocarbons, Chem. Rev., 1946, 39, 435-447. [all data]

Scott D.W., 1951
Scott D.W., Rotational isomerism and thermodynamic functions of 2-methylbutane and 2,3-dimethylbutane. Vapor heat capacity and heat of vaporization of 2-methylbutane, J. Am. Chem. Soc., 1951, 73, 1707-1712. [all data]

Notes

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Symbols used in this document:

C_p,gas Constant pressure heat capacity of gas

Δ_cH°_gas Enthalpy of combustion of gas at standard conditions

Δ_fH°_gas Enthalpy of formation of gas at standard conditions
Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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C_p,gas	Constant pressure heat capacity of gas
Δ_cH°_gas	Enthalpy of combustion of gas at standard conditions
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions