Neopentane

Formula: C₅H₁₂
Molecular weight: 72.1488
IUPAC Standard InChI: InChI=1S/C5H12/c1-5(2,3)4/h1-4H3
IUPAC Standard InChIKey: CRSOQBOWXPBRES-UHFFFAOYSA-N
CAS Registry Number: 463-82-1
Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
The 3d structure may be viewed using Java or Javascript.
Other names: Propane, 2,2-dimethyl-; tert-Pentane; Tetramethylcarbon; Tetramethylmethane; 1,1,1-Trimethylethane; 2,2-Dimethylpropane; Neo-C5H12; UN 2044; Dimethylpropane
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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	-167.9 ± 0.63	kJ/mol	Ccb	Good, 1970	ALS
Δ_fH°_gas	-168.5 ± 1.0	kJ/mol	Cm	Pilcher and Chadwick, 1967	ALS
Δ_fH°_gas	-166.0 ± 1.0	kJ/mol	Ccb	Prosen and Rossini, 1945	ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_gas	-3514.1 ± 0.96	kJ/mol	Cm	Pilcher and Chadwick, 1967	Corresponding Δ_fHº_gas = -168.5 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
120.82 ± 0.25	298.15	Hossenlopp I.A., 1981	GT
129.58 ± 0.26	323.15
138.41 ± 0.28	348.15
147.06 ± 0.29	373.15
155.46 ± 0.31	398.15
163.52 ± 0.32	423.15
171.46 ± 0.34	448.15
178.95 ± 0.36	473.15
186.42 ± 0.37	498.15
193.38 ± 0.39	523.15

Constant pressure heat capacity of gas

C_p,gas (J/mol*K)	Temperature (K)	Reference	Comment
80.54	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 calculation [ Pitzer K.S., 1946].; GT
111.63	273.15
120.83 ± 0.25	298.15
121.55	300.
155.98	400.
186.98	500.
214.64	600.
238.91	700.
261.08	800.
280.33	900.
297.90	1000.
313.38	1100.
327.19	1200.
338.90	1300.
351.46	1400.
359.82	1500.

Condensed phase thermochemistry data

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Data compiled as indicated in comments:
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DH - Eugene S. Domalski and Elizabeth D. Hearing

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_liquid	-190.3 ± 0.63	kJ/mol	Ccb	Good, 1970	ALS
Δ_fH°_liquid	-188.2 ± 1.0	kJ/mol	Ccb	Prosen and Rossini, 1945	ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_liquid	-3492.4 ± 0.59	kJ/mol	Ccb	Good, 1970	Reanalyzed by Pedley, Naylor, et al., 1986, Original value = -3492.2 ± 0.50 kJ/mol; Corresponding Δ_fHº_liquid = -190.1 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
Δ_cH°_liquid	-3494.4 ± 1.0	kJ/mol	Ccb	Prosen and Rossini, 1945	Corresponding Δ_fHº_liquid = -188.2 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
Quantity	Value	Units	Method	Reference	Comment
S°_liquid	216.81	J/mol*K	N/A	Enokida, Shinoda, et al., 1969	At normal boiling point.; DH
S°_liquid	218.8	J/mol*K	N/A	Aston and Messerly, 1936	DH

Constant pressure heat capacity of liquid

C_p,liquid (J/mol*K)	Temperature (K)	Reference	Comment
153.09	259.93	Enokida, Shinoda, et al., 1969	T = 4 to 260 K. Value is unsmoothed experimental datum.; DH
163.89	278.92	Aston and Messerly, 1936	T = 13 to 283 K. Value is unsmoothed experimental datum.; DH

Reaction thermochemistry data

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Data compiled as indicated in comments:
B - John E. Bartmess
MS - José A. Martinho Simões

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Individual Reactions

C₅H₁₁^- + = Neopentane

By formula: C₅H₁₁^- + H⁺ = C₅H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1711. ± 8.4	kJ/mol	Bran	DePuy, Gronert, et al., 1989	gas phase; B
Δ_rH°	1720. ± 42.	kJ/mol	CIDT	Graul and Squires, 1990	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1674. ± 8.8	kJ/mol	H-TS	DePuy, Gronert, et al., 1989	gas phase; B

C₁₀H₂₂Mg (cr) + (g) + (l) = 2 Neopentane (l) + Br₂Mg (cr)

By formula: C₁₀H₂₂Mg (cr) + H₂ (g) + Br₂ (l) = 2C₅H₁₂ (l) + Br₂Mg (cr)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-669.6 ± 6.6	kJ/mol	RSC	Akkerman, Schat, et al., 1983	MS

References

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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]

Hossenlopp I.A., 1981
Hossenlopp I.A., Vapor heat capacities and enthalpies of vaporization of five alkane hydrocarbons, J. Chem. Thermodyn., 1981, 13, 415-421. [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]

Pedley, Naylor, et al., 1986
Pedley, J.B.; Naylor, R.D.; Kirby, S.P., Thermochemical Data of Organic Compounds, Chapman and Hall, New York, 1986, 1-792. [all data]

Enokida, Shinoda, et al., 1969
Enokida, H.; Shinoda, T.; Mashiko, Y., Thermodynamic properties of neopentane from 4K to the melting point and comparison with spectroscopic data, Bull. Chem. Soc. Japan, 1969, 42, 84-91. [all data]

Aston and Messerly, 1936
Aston, J.G.; Messerly, G.H., Heat capacities and entropies of organic compounds. II. Thermal and vapor pressure data for tetramethylmethane from 13.22°K to the boiling point. The entropy from its Raman spectrum, J. Am. Chem. Soc., 1936, 58, 2354-2361. [all data]

DePuy, Gronert, et al., 1989
DePuy, C.H.; Gronert, S.; Barlow, S.E.; Bierbaum, V.M.; Damrauer, R., The Gas Phase Acidities of the Alkanes, J. Am. Chem. Soc., 1989, 111, 6, 1968, https://doi.org/10.1021/ja00188a003 . [all data]

Graul and Squires, 1990
Graul, S.T.; Squires, R.R., Gas-Phase Acidities Derived from Threshold Energies for Activated Reactions, J. Am. Chem. Soc., 1990, 112, 7, 2517, https://doi.org/10.1021/ja00163a007 . [all data]

Akkerman, Schat, et al., 1983
Akkerman, O.S.; Schat, G.; Evers, E.A.I.M.; Bickelhaupt, F., Recl. Trav. Chim. Pays-Bas, 1983, 102, 109. [all data]

Notes

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Symbols used in this document:

C_p,gas	Constant pressure heat capacity of gas
C_p,liquid	Constant pressure heat capacity of liquid
S°_liquid	Entropy of liquid at standard conditions
Δ_cH°_gas	Enthalpy of combustion of gas at standard conditions
Δ_cH°_liquid	Enthalpy of combustion of liquid at standard conditions
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions
Δ_fH°_liquid	Enthalpy of formation of liquid at standard conditions
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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