2-Methyl-1-butene

Formula: C₅H₁₀
Molecular weight: 70.1329
IUPAC Standard InChI: InChI=1S/C5H10/c1-4-5(2)3/h2,4H2,1,3H3
IUPAC Standard InChIKey: MHNNAWXXUZQSNM-UHFFFAOYSA-N
CAS Registry Number: 563-46-2
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: 1-Butene, 2-methyl-; γ-Isoamylene; 1-Isoamylene; C2H5C(CH3)=CH2; 2-Methylbutene-1; Isopentene; UN 2371; UN 2459; 2-methylbut-1-ene
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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	-60.96 ± 0.84	kJ/mol	Ccb	Good and Smith, 1979	ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_liquid	-3335.74 ± 0.80	kJ/mol	Ccb	Good and Smith, 1979	Corresponding Δ_fHº_liquid = -60.96 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
Quantity	Value	Units	Method	Reference	Comment
S°_liquid	254.0	J/mol*K	N/A	Chao, Hall, et al., 1983	DH
S°_liquid	253.97	J/mol*K	N/A	Todd, Oliver, et al., 1947	DH

Constant pressure heat capacity of liquid

C_p,liquid (J/mol*K)	Temperature (K)	Reference	Comment
157.3	298.15	Chao, Hall, et al., 1983	T = 12 to 293 K.; DH
157.19	298.15	Todd, Oliver, et al., 1947	T = 12 to 300 K.; DH

Reaction thermochemistry data

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Data compiled by: Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.

Individual Reactions

+ 2-Methyl-1-butene =

By formula: H₂ + C₅H₁₀ = C₅H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-126.95	kJ/mol	Chyd	Dolliver, Gresham, et al., 1937	gas phase; At 355 °K
Δ_rH°	-118.2 ± 0.42	kJ/mol	Chyd	Kistiakowsky, Ruhoff, et al., 1936	gas phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -119.2 ± 1.5 kJ/mol; At 355 K

2-Methyl-1-butene + =

By formula: C₅H₁₀ + CH₄O = C₆H₁₄O

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-35.8	kJ/mol	Eqk	Serda, Izquierdo, et al., 1995	liquid phase
Δ_rH°	-20.4 ± 0.8	kJ/mol	Eqk	Hwang and Wu, 1994	liquid phase
Δ_rH°	-33.6 ± 5.1	kJ/mol	Eqk	Rihko, Linnekoski, et al., 1994	liquid phase; solvent: Alcohol/alkane mixture

2-Methyl-1-butene =

By formula: C₅H₁₀ = C₅H₁₀

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-6.7 ± 3.0	kJ/mol	Eqk	Rihko, Linnekoski, et al., 1994	liquid phase; solvent: Methanol/H+
Δ_rH°	-8.0 ± 1.4	kJ/mol	Eqk	Rihko, Linnekoski, et al., 1994	liquid phase; solvent: Ethanol/H+

2-Methyl-1-butene + =

By formula: C₅H₁₀ + HCl = C₅H₁₁Cl

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-63.7 ± 1.4	kJ/mol	Cm	Arnett and Pienta, 1980	liquid phase; solvent: Methylene chloride; Hydrochlorination

2-Methyl-1-butene + =

By formula: C₅H₁₀ + C₂H₆O = C₇H₁₆O

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-35.2 ± 5.8	kJ/mol	Eqk	Rihko, Linnekoski, et al., 1994	liquid phase; solvent: Alcohol/alkane mixture

2-Methyl-1-butene + =

By formula: C₅H₁₀ + C₂HF₃O₂ = C₇H₁₁F₃O₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-45.7 ± 0.2	kJ/mol	Cm	Wiberg and Hao, 1991	liquid phase; Trifuoroacetolysis

= 2-Methyl-1-butene

By formula: C₅H₁₀ = C₅H₁₀

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	8.08 ± 0.50	kJ/mol	Eqk	Radyuk, Kabo, et al., 1973	gas phase; Heat of isomerization at 562 K

2-Methyl-1-butene + =

By formula: C₅H₁₀ + CH₄O = C₆H₁₄O

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-35.8 ± 1.3	kJ/mol	Eqk	Serda, Izquierdo, et al., 1995	liquid phase

= 2-Methyl-1-butene +

By formula: C₆H₁₄O = C₅H₁₀ + CH₄O

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	67.96 ± 0.39	kJ/mol	Eqk	Rozhnov, Safronov, et al., 1991	liquid phase

Gas phase ion energetics data

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Data evaluated as indicated in comments:
L - Sharon G. Lias

Data compiled as indicated in comments:
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron

View reactions leading to C₅H₁₀⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	9.12 ± 0.01	eV	N/A	N/A	L

Ionization energy determinations

IE (eV)	Method	Reference	Comment
9.10	PI	Traeger, 1986	LBLHLM
9.148 ± 0.003	PE	Masclet, Grosjean, et al., 1973	LLK
9.12	EI	Lossing, 1972	LLK
9.35 ± 0.08	EI	Gross and Wilkins, 1971	LLK
9.12 ± 0.02	PI	Demeo and El-Sayed, 1970	RDSH
9.12 ± 0.02	PI	Watanabe, Nakayama, et al., 1962	RDSH
9.2 ± 0.1	PE	Bieri, Burger, et al., 1977	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
C₃H₆⁺	11.66 ± 0.06	C₂H₄	EI	Gross and Wilkins, 1971	LLK
C₄H₇⁺	10.66	CH₃	PI	Traeger, 1986	LBLHLM
C₄H₇⁺	10.85	CH₃	EI	Brand and Baer, 1984	LBLHLM
C₄H₇⁺	10.85	CH₃	EI	Lossing, 1972	LLK
C₄H₇⁺	11.34 ± 0.07	CH₃	EI	Gross and Wilkins, 1971	LLK

References

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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]

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]

Dolliver, Gresham, et al., 1937
Dolliver, M.a.; Gresham, T.L.; Kistiakowsky, G.B.; Vaughan, W.E., Heats of organic reactions. V. Heats of hydrogenation of various hydrocarbons, J. Am. Chem. Soc., 1937, 59, 831-841. [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]

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

Hwang and Wu, 1994
Hwang, W.-S.; Wu, J.-C., Kinetics and thermodynamics of synthesis of tertiary-amyl methyl ether catalyzed by ion-exchange resin, J. Chin. Chem. Soc. (Taipei), 1994, 41, 181-186. [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]

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]

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]

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]

Rozhnov, Safronov, et al., 1991
Rozhnov, A.M.; Safronov, V.V.; Verevkin, S.P.; Sharonov, K.G.; Alenin, V.I., Enthalpy of combustion and enthalpy of vaporization of 2-ethyl-2-methoxypropane and thermodynamics of its gas-phase synthesis from (methanol + a 2-methylbutene), J. Chem. Thermodyn., 1991, 23, 629-635. [all data]

Traeger, 1986
Traeger, J.C., Heat of formation for the 1-methylallyl cation by photoionization mass spectrometry, J. Phys. Chem., 1986, 90, 4114. [all data]

Masclet, Grosjean, et al., 1973
Masclet, P.; Grosjean, D.; Mouvier, G., Alkene ionization potentials. Part I. Quantitative determination of alkyl group structural effects, J. Electron Spectrosc. Relat. Phenom., 1973, 2, 225. [all data]

Lossing, 1972
Lossing, F.P., Free radicals by mass spectrometry. XLV. Ionization potentials and heats of formation of C₃H₃, C₃H₅, and C₄H₇ radicals and ions, Can. J. Chem., 1972, 50, 3973. [all data]

Gross and Wilkins, 1971
Gross, M.L.; Wilkins, C.L., Computer-assisted ion cyclotron resonance appearance potential measurements for C₅H₁₀ isomers, Anal. Chem., 1971, 43, 1624. [all data]

Demeo and El-Sayed, 1970
Demeo, D.A.; El-Sayed, M.A., Ionization potential and structure of olefins, J. Chem. Phys., 1970, 52, 2622. [all data]

Watanabe, Nakayama, et al., 1962
Watanabe, K.; Nakayama, T.; Mottl, J., Ionization potentials of some molecules, J. Quant. Spectry. Radiative Transfer, 1962, 2, 369. [all data]

Bieri, Burger, et al., 1977
Bieri, G.; Burger, F.; Heilbronner, E.; Maier, J.P., Valence ionization enrgies of hydrocarbons, Helv. Chim. Acta, 1977, 60, 2213. [all data]

Brand and Baer, 1984
Brand, W.A.; Baer, T., Dissociation dynamics of energy-selected C₅H₁₀⁺ ions, J. Am. Chem. Soc., 1984, 106, 3154. [all data]

Notes

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Symbols used in this document:

AE	Appearance energy
C_p,liquid	Constant pressure heat capacity of liquid
IE (evaluated)	Recommended ionization energy
S°_liquid	Entropy of liquid at standard conditions
Δ_cH°_liquid	Enthalpy of combustion of liquid at standard conditions
Δ_fH°_liquid	Enthalpy of formation of liquid 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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