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

Go To: Top, Condensed phase thermochemistry data, Reaction thermochemistry data, References, Notes

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	-9.92 ± 0.21	kcal/mol	Eqk	Wiberg and Hao, 1991	Heat of hydration; ALS
Δ_fH°_gas	-9.80	kcal/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 (cal/mol*K)	Temperature (K)	Reference	Comment
26.530 ± 0.079	319.04	Scott D.W., 1949	GT
29.391 ± 0.088	362.37
32.010 ± 0.096	402.26
34.19 ± 0.10	436.18
36.34 ± 0.11	471.09

Constant pressure heat capacity of gas

C_p,gas (cal/mol*K)	Temperature (K)	Reference	Comment
25.100	298.15	Scott D.W., 1949	Recommended results of statistical thermodynamics calculation are in good agreement with experimental data.; GT
25.220	300.
31.931	400.
38.069	500.
43.420	600.
48.040	700.
52.051	800.
55.521	900.
58.549	1000.
61.159	1100.
63.449	1200.
65.418	1300.
67.139	1400.
68.630	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	-16.4 ± 0.2	kcal/mol	Eqk	Wiberg and Hao, 1991	Heat of hydration; ALS
Δ_fH°_liquid	-16.27 ± 0.31	kcal/mol	Ccb	Good and Smith, 1979	ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_liquid	-795.56 ± 0.30	kcal/mol	Ccb	Good and Smith, 1979	Corresponding Δ_fHº_liquid = -16.27 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS
Quantity	Value	Units	Method	Reference	Comment
S°_liquid	60.04	cal/mol*K	N/A	Chao, Hall, et al., 1983	DH
S°_liquid	60.000	cal/mol*K	N/A	Todd, Oliver, et al., 1947	DH
S°_liquid	59.49	cal/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 (cal/mol*K)	Temperature (K)	Reference	Comment
36.52	298.15	Chao, Hall, et al., 1983	T = 13 to 301 K.; DH
36.520	298.15	Todd, Oliver, et al., 1947	T = 12 to 300 K.; DH
34.99	293.9	Parks and Huffman, 1930	T = 93 to 294 K. Value is unsmoothed experimental datum.; DH

Reaction thermochemistry data

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, References, Notes

Data compiled as indicated in comments:
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias

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Individual Reactions

= 2-Butene, 2-methyl-

By formula: C₅H₁₀ = C₅H₁₀

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-1.6 ± 0.72	kcal/mol	Eqk	Rihko, Linnekoski, et al., 1994	liquid phase; solvent: Methanol/H+; ALS
Δ_rH°	-1.9 ± 0.33	kcal/mol	Eqk	Rihko, Linnekoski, et al., 1994	liquid phase; solvent: Ethanol/H+; ALS

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

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

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	38.2	kcal/mol	PHPMS	Li and Stone, 1989	gas phase; condesation; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	48.0	cal/mol*K	PHPMS	Li and Stone, 1989	gas phase; condesation; M

2-Butene, 2-methyl- + =

By formula: C₅H₁₀ + CH₄O = C₆H₁₄O

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-7.84	kcal/mol	Eqk	Serda, Izquierdo, et al., 1995	liquid phase; ALS
Δ_rH°	-6.41 ± 0.55	kcal/mol	Eqk	Rihko, Linnekoski, et al., 1994	liquid phase; solvent: Alcohol/alkane mixture; ALS

2-Butene, 2-methyl- + =

By formula: C₅H₁₀ + HCl = C₅H₁₁Cl

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-14.12 ± 0.22	kcal/mol	Cm	Arnett and Pienta, 1980	liquid phase; solvent: Methylene chloride; Hydrochloroination; ALS

2-Butene, 2-methyl- + =

By formula: C₅H₁₀ + C₂H₆O = C₇H₁₆O

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-6.5 ± 1.6	kcal/mol	Eqk	Rihko, Linnekoski, et al., 1994	liquid phase; solvent: Alcohol/alkane mixture; ALS

2-Butene, 2-methyl- + =

By formula: C₅H₁₀ + C₂HF₃O₂ = C₇H₁₁F₃O₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-9.11 ± 0.04	kcal/mol	Cm	Wiberg and Hao, 1991	liquid phase; Trifluoroacetolysis; ALS

2-Butene, 2-methyl- =

By formula: C₅H₁₀ = C₅H₁₀

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.40 ± 0.35	kcal/mol	Eqk	Radyuk, Kabo, et al., 1973	gas phase; Heat of isomerization at 622 K; ALS

2-Butene, 2-methyl- =

By formula: C₅H₁₀ = C₅H₁₀

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.93 ± 0.12	kcal/mol	Eqk	Radyuk, Kabo, et al., 1973	gas phase; Heat of isomerization at 562 K; ALS

2-Butene, 2-methyl- + =

By formula: C₅H₁₀ + Br₂ = C₅H₁₀Br₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-30.40 ± 0.20	kcal/mol	Cm	Conn, Kistiakowsky, et al., 1938	gas phase; At 355 °K; ALS

+ 2-Butene, 2-methyl- =

By formula: H₂ + C₅H₁₀ = C₅H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-26.68 ± 0.06	kcal/mol	Chyd	Kistiakowsky, Ruhoff, et al., 1936	gas phase; ALS

2-Butene, 2-methyl- + =

By formula: C₅H₁₀ + CH₄O = C₆H₁₄O

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-7.84 ± 0.33	kcal/mol	Eqk	Serda, Izquierdo, et al., 1995	liquid phase; ALS

= 2-Butene, 2-methyl- +

By formula: C₇H₁₆O = C₅H₁₀ + C₂H₆O

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.16 ± 0.19	kcal/mol	Eqk	Sharonov, Rozhnov, et al., 1995	liquid phase; ALS

References

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Reaction thermochemistry 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]

Rihko, Linnekoski, et al., 1994
Rihko, L.K.; Linnekoski, J.A.; Krause, A.O., Reaction equilibria in the synthesis of 2-methoxy-2-methylbutane and 2-ethyoxy-2-methylbutane in the liquid phase, J. Chem. Eng. Data, 1994, 39, 700-704. [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]

Serda, Izquierdo, et al., 1995
Serda, J.A.; Izquierdo, J.F.; Tejero, J.; Cunill, F.; Iborra, M., Equilibrium and thermodynamics for 2-methyl-2-methoxybutane liquid-phase decomposition, Thermochim. Acta, 1995, 259, 111-120. [all data]

Arnett and Pienta, 1980
Arnett, E.M.; Pienta, N.J., Stabilities of carbonium ions in solution. 12. Heats of formation of alkyl chlorides as an entree to heats of solvation of aliphatic carbonium ions, J. Am. Chem. Soc., 1980, 102, 3329-3334. [all data]

Radyuk, Kabo, et al., 1973
Radyuk, Z.A.; Kabo, G.Ya.; Andreevskii, D.N., Isomerization equilibrium and thermodynamic properties of methylbutenes, Neftekhimiya, 1973, 13, 356-360. [all data]

Conn, Kistiakowsky, et al., 1938
Conn, J.B.; Kistiakowsky, G.B.; Smith, E.A., Heats of organic reactions. VII. Addition of halogens to olefins, J. Am. Chem. Soc., 1938, 60, 2764-2771. [all data]

Kistiakowsky, Ruhoff, et al., 1936
Kistiakowsky, G.B.; Ruhoff, J.R.; Smith, H.A.; Vaughan, W.E., Heats of organic reactions. III. Hydrogenation of some higher olefins, J. Am. Chem. Soc., 1936, 58, 137-145. [all data]

Sharonov, Rozhnov, et al., 1995
Sharonov, K.G.; Rozhnov, A.M.; Korol'kov, A.V.; Karaseva, S.Y., Enthalpies of formation of 2-methyl-2-ethoxypropane and 2-ethyl-2-ethoxypropane from equilibrium measurements, J. Chem. Thermodyn., 1995, 27, 751-753. [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Reaction thermochemistry data, References

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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