Cyclopentane, methyl-

Formula: C₆H₁₂
Molecular weight: 84.1595
IUPAC Standard InChI: InChI=1S/C6H12/c1-6-4-2-3-5-6/h6H,2-5H2,1H3
IUPAC Standard InChIKey: GDOPTJXRTPNYNR-UHFFFAOYSA-N
CAS Registry Number: 96-37-7
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: Methylcyclopentane; UN 2298
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Gas phase thermochemistry data

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Data compiled as indicated in comments:
DRB - Donald R. Burgess, Jr.
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	-25.33	kcal/mol	N/A	Good and Smith, 1969	Value computed using Δ_fH_liquid° value of -137.7±0.7 kj/mol from Good and Smith, 1969 and Δ_vapH° value of 31.7 kj/mol from Prosen, Johnson, et al., 1946.; DRB
Δ_fH°_gas	-25.50 ± 0.20	kcal/mol	Ccb	Prosen, Johnson, et al., 1946	ALS
Δ_fH°_gas	-25.84	kcal/mol	N/A	Moore, Renquist, et al., 1940	Value computed using Δ_fH_liquid° value of -139.8±1.7 kj/mol from Moore, Renquist, et al., 1940 and Δ_vapH° value of 31.7 kj/mol from Prosen, Johnson, et al., 1946.; DRB

Constant pressure heat capacity of gas

C_p,gas (cal/mol*K)	Temperature (K)	Reference	Comment
10.35	50.	Thermodynamics Research Center, 1997	p=1 bar. Selected values of S(T) and Cp(T) are in close agreement with those calculated by [ Scott D.W., 1960] at low temperatures. Discrepancies increase up to 1.8 J/mol*K at 1000-1500 K.; GT
12.67	100.
14.97	150.
17.87	200.
23.81	273.15
26.17	298.15
26.36	300.
36.21	400.
45.15	500.
52.65	600.
58.94	700.
64.20	800.
68.69	900.
72.51	1000.
75.79	1100.
78.61	1200.
81.02	1300.
83.13	1400.
84.94	1500.
88.53	1750.
91.09	2000.
93.00	2250.
94.43	2500.
95.53	2750.
96.39	3000.

Constant pressure heat capacity of gas

C_p,gas (cal/mol*K)	Temperature (K)	Reference	Comment
29.694 ± 0.060	333.20	McCullough J.P., 1959	GT
32.555 ± 0.065	362.55
36.365 ± 0.072	402.35
39.486 ± 0.079	436.25
42.584 ± 0.086	471.05

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

+ = Cyclopentane, methyl-

By formula: H₂ + C₆H₁₀ = C₆H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-24.09 ± 0.15	kcal/mol	Chyd	Rogers, Crooks, et al., 1987	liquid phase
Δ_rH°	-24.22 ± 0.12	kcal/mol	Chyd	Allinger, Dodziuk, et al., 1982	liquid phase; solvent: Hexane
Δ_rH°	-23.01 ± 0.04	kcal/mol	Chyd	Turner and Garner, 1958	liquid phase; solvent: Acetic acid
Δ_rH°	-23.01 ± 0.04	kcal/mol	Chyd	Turner and Garner, 1957	liquid phase; solvent: Acetic acid
Δ_rH°	-23.01 ± 0.04	kcal/mol	Chyd	Turner and Garner, 1957, 2	liquid phase; solvent: Acetic acid

+ = Cyclopentane, methyl-

By formula: H₂ + C₆H₁₀ = C₆H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-27.70 ± 0.23	kcal/mol	Chyd	Allinger, Dodziuk, et al., 1982	liquid phase; solvent: Hexane
Δ_rH°	-26.88 ± 0.02	kcal/mol	Chyd	Turner and Garner, 1958	liquid phase; solvent: Acetic acid
Δ_rH°	-26.85 ± 0.05	kcal/mol	Chyd	Turner and Garner, 1957	liquid phase; solvent: Acetic acid
Δ_rH°	-26.82 ± 0.08	kcal/mol	Chyd	Turner and Garner, 1957, 2	liquid phase; solvent: Acetic acid

+ = Cyclopentane, methyl-

By formula: C₆H₁₀ + H₂ = C₆H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-27.58 ± 0.18	kcal/mol	Chyd	Allinger, Dodziuk, et al., 1982	liquid phase; solvent: Hexane

Cyclopentane, methyl- =

By formula: C₆H₁₂ = C₆H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-3.510	kcal/mol	Eqk	Glasebrook and Lovell, 1939	liquid phase; Heat of isomerization

2 + = Cyclopentane, methyl-

By formula: 2H₂ + C₆H₈ = C₆H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-63.1 ± 0.2	kcal/mol	Chyd	Roth, Adamczak, et al., 1991	liquid phase

3 + = Cyclopentane, methyl-

By formula: 3H₂ + C₆H₆ = C₆H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-78.9 ± 0.1	kcal/mol	Chyd	Roth, Adamczak, et al., 1991	liquid phase

2 + = Cyclopentane, methyl-

By formula: 2H₂ + C₆H₈ = C₆H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-52.9 ± 0.2	kcal/mol	Chyd	Roth, Adamczak, et al., 1991	liquid phase

= Cyclopentane, methyl-

By formula: C₆H₁₂ = C₆H₁₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	4.32 ± 0.28	kcal/mol	Eqk	Kabo and Andreevskii, 1973	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:
LL - Sharon G. Lias and Joel F. Liebman
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 C₆H₁₂⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	9.7 ± 0.1	eV	N/A	N/A	L

Ionization energy determinations

IE (eV)	Method	Reference	Comment
9.62 ± 0.05	EI	Holmes and Lossing, 1991	LL
9.85	EQ	Lias, Ausloos, et al., 1976	LLK
10.42	EI	Lossing and Traeger, 1975	LLK
10.34 ± 0.04	PE	Rang, Paldoia, et al., 1974	LLK
10.45	EI	Pottie, Harrison, et al., 1961	RDSH

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
C₅H₉⁺	10.42	CH₃	EI	Lossing and Traeger, 1975, 2	LLK
C₅H₉⁺	10.73	CH₃	EI	Lossing and Traeger, 1975	LLK
C₅H₉⁺	10.95	CH₃	EI	Pottie, Harrison, et al., 1961	RDSH

References

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Good and Smith, 1969
Good, W.D.; Smith, N.K., Enthalpies of combustion of toluene, benzene, cyclohexane, cyclohexene, methylcyclopentane, 1-methylcyclopentene, and n-hexane, J. Chem. Eng. Data, 1969, 14, 102-106. [all data]

Prosen, Johnson, et al., 1946
Prosen, E.J.; Johnson, W.H.; Rossini, F.D., Heats of formation and combustion of the normal alkylcyclopentanes and cyclohexanes and the increment per CH₂ group for several homologous series of hydrocarbons, J. Res. NBS, 1946, 37, 51-56. [all data]

Moore, Renquist, et al., 1940
Moore, G.E.; Renquist, M.L.; Parks, G.S., Thermal data on organic compounds. XX. Modern combustion data for two methylnonanes, methyl ethyl ketone, thiophene and six cycloparaffins, J. Am. Chem. Soc., 1940, 62, 1505-1507. [all data]

Thermodynamics Research Center, 1997
Thermodynamics Research Center, Selected Values of Properties of Chemical Compounds., Thermodynamics Research Center, Texas A&M University, College Station, Texas, 1997. [all data]

Scott D.W., 1960
Scott D.W., Chemical thermodynamic properties of methylcyclopentane and 1-cis-3-dimethylcyclopentane, J. Phys. Chem., 1960, 64, 906-908. [all data]

McCullough J.P., 1959
McCullough J.P., Thermodynamics of cyclopentane, methylcyclopentane and 1,cis-3-dimethylcyclopentane: verification of the concept of pseudorotation, J. Am. Chem. Soc., 1959, 81, 5880-5883. [all data]

Rogers, Crooks, et al., 1987
Rogers, D.W.; Crooks, E.; Dejroongruang, K., Enthalpies of hydrogenation of the hexenes, J. Chem. Thermodyn., 1987, 19, 1209-1215. [all data]

Allinger, Dodziuk, et al., 1982
Allinger, N.L.; Dodziuk, H.; Rogers, D.W.; Naik, S.N., Heats of hydrogenation and formation of some 5-membered ring compounds by molecular mechanics calculations and direct measurements, Tetrahedron, 1982, 38, 1593-1597. [all data]

Turner and Garner, 1958
Turner, R.B.; Garner, R.H., Heats of hydrogenation. V. Relative stabilities in certain exocyclic-endocyclic olefin pairs, J. Am. Chem. Soc., 1958, 80, 1424-1430. [all data]

Turner and Garner, 1957
Turner, R.B.; Garner, R.H., Heats of hydrogenation. V. Relative stabilities in certain exocyclic-endocyclic olefin pairs, J. Am. Chem. Soc., 1957, 80, 1424-1430. [all data]

Turner and Garner, 1957, 2
Turner, R.B.; Garner, R.H., The stability relationship of 1-methyl-cyclopentene and methylenecyclopentane, J. Am. Chem. Soc., 1957, 79, 253. [all data]

Glasebrook and Lovell, 1939
Glasebrook, A.L.; Lovell, W.G., The isomerization of cyclohexane and methylcyclopentane, J. Am. Chem. Soc., 1939, 61, 1717-1720. [all data]

Roth, Adamczak, et al., 1991
Roth, W.R.; Adamczak, O.; Breuckmann, R.; Lennartz, H.-W.; Boese, R., Die Berechnung von Resonanzenergien; das MM2ERW-Kraftfeld, Chem. Ber., 1991, 124, 2499-2521. [all data]

Kabo and Andreevskii, 1973
Kabo, G.Ya.; Andreevskii, D.N., Thermodynamic characteristics of the cyclohexane = methylcyclopentane isomerization, Zh. Fiz. Khim., 1973, 47, 272-273. [all data]

Holmes and Lossing, 1991
Holmes, J.L.; Lossing, F.P., Ionization energies of homologous organic compounds and correlation with molecular size, Org. Mass Spectrom., 1991, 26, 537. [all data]

Lias, Ausloos, et al., 1976
Lias, S.G.; Ausloos, P.; Horvath, Z., Charge transfer reactions in alkane and cycloalkane systems. Estimated ionization potentials, Int. J. Chem. Kinet., 1976, 8, 725. [all data]

Lossing and Traeger, 1975
Lossing, F.P.; Traeger, J.C., Stabilization in cyclopentadienyl, cyclopentenyl, and cyclopentyl cations, J. Am. Chem. Soc., 1975, 97, 1579. [all data]

Rang, Paldoia, et al., 1974
Rang, S.; Paldoia, P.; Talvari, A., Ionization potentials of unsaturated hydrocarbons. 2. Mono-substituted cyclopentenes and cyclohexenes, Eesti. NSV Tead. Akad. Toim., 1974, 354. [all data]

Pottie, Harrison, et al., 1961
Pottie, R.F.; Harrison, A.G.; Lossing, F.P., Free radicals by mass spectrometry. XXIV. Ionization potentials of cycloalkyl free radicals and cycloalkanes, J. Am. Chem. Soc., 1961, 83, 3204. [all data]

Lossing and Traeger, 1975, 2
Lossing, F.P.; Traeger, J.C., Free radicals by mass spectrometry XLVI. Heats of formation of C₅H₇ and C₅H₉ radicals and cations., J. Am. Chem. Soc., 1975, 19, 9. [all data]

Notes

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Symbols used in this document:

AE	Appearance energy
C_p,gas	Constant pressure heat capacity of gas
IE (evaluated)	Recommended ionization energy
Δ_fH°_gas	Enthalpy of formation of gas 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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