2-Butene, 2-methyl-

Formula: C₅H₁₀
Molecular weight: 70.1329
IUPAC Standard InChI: InChI=1S/C5H10/c1-4-5(2)3/h4H,1-3H3
IUPAC Standard InChIKey: BKOOMYPCSUNDGP-UHFFFAOYSA-N
CAS Registry Number: 513-35-9
Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
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Other names: Trimethylethylene; β-Isoamylene; Amylene; 1,1,2-Trimethylethylene; 2-Methyl-2-butene; 3-Methyl-2-butene; (CH3)2C=CHCH3; 2-Methylbut-2-ene; n-Amylene; Ethylene, trimethyl-; UN 2460; 2-Methylbutene-2; NSC 74118; Isopentene
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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
DRB - Donald R. Burgess, Jr.
GT - Glushko Thermocenter, Russian Academy of Sciences, Moscow

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	-41.5 ± 0.88	kJ/mol	Eqk	Wiberg and Hao, 1991	Heat of hydration; ALS
Δ_fH°_gas	-41.0	kJ/mol	N/A	Good and Smith, 1979	Value computed using Δ_fH_liquid° value of -68.1±1.3 kj/mol from Good and Smith, 1979 and Δ_vapH° value of 27.1 kj/mol from Wiberg and Hao, 1991.; DRB

Constant pressure heat capacity of gas

C_p,gas (J/mol*K)	Temperature (K)	Reference	Comment
111.00 ± 0.33	319.04	Scott D.W., 1949	GT
122.97 ± 0.37	362.37
133.93 ± 0.40	402.26
143.05 ± 0.43	436.18
152.05 ± 0.46	471.09

Constant pressure heat capacity of gas

C_p,gas (J/mol*K)	Temperature (K)	Reference	Comment
105.02	298.15	Scott D.W., 1949	Recommended results of statistical thermodynamics calculation are in good agreement with experimental data.; GT
105.52	300.
133.60	400.
159.28	500.
181.67	600.
201.00	700.
217.78	800.
232.30	900.
244.97	1000.
255.89	1100.
265.47	1200.
273.71	1300.
280.91	1400.
287.15	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	-68.6 ± 0.8	kJ/mol	Eqk	Wiberg and Hao, 1991	Heat of hydration; ALS
Δ_fH°_liquid	-68.1 ± 1.3	kJ/mol	Ccb	Good and Smith, 1979	ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_liquid	-3328.6 ± 1.3	kJ/mol	Ccb	Good and Smith, 1979	Corresponding Δ_fHº_liquid = -68.08 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
Quantity	Value	Units	Method	Reference	Comment
S°_liquid	251.2	J/mol*K	N/A	Chao, Hall, et al., 1983	DH
S°_liquid	251.04	J/mol*K	N/A	Todd, Oliver, et al., 1947	DH
S°_liquid	248.9	J/mol*K	N/A	Parks and Huffman, 1930	Extrapolation below 90 K, 13.12 cal/mol*K.; DH

Constant pressure heat capacity of liquid

C_p,liquid (J/mol*K)	Temperature (K)	Reference	Comment
152.8	298.15	Chao, Hall, et al., 1983	T = 13 to 301 K.; DH
152.80	298.15	Todd, Oliver, et al., 1947	T = 12 to 300 K.; DH
146.4	293.9	Parks and Huffman, 1930	T = 93 to 294 K. Value is unsmoothed experimental datum.; DH

Ion clustering data

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Data compiled by: Michael M. Meot-Ner (Mautner) and Sharon G. Lias

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. Searches may be limited to ion clustering reactions. A general reaction search form is also available.

Clustering reactions

C₃H₉Si⁺ + 2-Butene, 2-methyl- = (C₃H₉Si⁺ • )

By formula: C₃H₉Si⁺ + C₅H₁₀ = (C₃H₉Si⁺ • C₅H₁₀)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	160.	kJ/mol	PHPMS	Li and Stone, 1989	gas phase; condesation
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	201.	J/mol*K	PHPMS	Li and Stone, 1989	gas phase; condesation

References

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Ion clustering data, Notes

Wiberg and Hao, 1991
Wiberg, K.B.; Hao, S., Enthalpies of hydration of alkenes. 4. Formation of acyclic tert-alcohols, J. Org. Chem., 1991, 56, 5108-5110. [all data]

Good and Smith, 1979
Good, W.D.; Smith, N.K., The enthalpies of combustion of the isomeric pentenes in the liquid state. A warning to combustion calorimetrists about sample drying, J. Chem. Thermodyn., 1979, 11, 111-118. [all data]

Scott D.W., 1949
Scott D.W., Thermodynamic properties of three isomeric pentenes, J. Am. Chem. Soc., 1949, 71, 2767-2773. [all data]

Chao, Hall, et al., 1983
Chao, J.; Hall, K.R.; Yao, J.M., Thermodynamic properties of simple alkenes, Thermochim. Acta, 1983, 64(3), 285-303. [all data]

Todd, Oliver, et al., 1947
Todd, S.S.; Oliver, G.D.; Huffman, H.M., The heat capacities, heats of fusion and entropies of the six pentenes, J. Am. Chem. Soc., 1947, 69, 1519-1525. [all data]

Parks and Huffman, 1930
Parks, G.S.; Huffman, H.M., Thermal data on organic compounds. IX. A study of the effect of unsaturation on the heat capacities, entropies and free energies of some hydrocarbons and other compounds, J. Am. Chem. Soc., 1930, 52, 4381-4391. [all data]

Li and Stone, 1989
Li, X.; Stone, J.A., Determination of the beta silicon effect from a mass spectrometric study of the association of trimethylsilylium ion with alkenes, J. Am. Chem. Soc., 1989, 111, 15, 5586, https://doi.org/10.1021/ja00197a013 . [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°_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_rH°	Enthalpy of reaction at standard conditions
Δ_rS°	Entropy of reaction at standard conditions

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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