Cyclopentane

Formula: C₅H₁₀
Molecular weight: 70.1329
IUPAC Standard InChI: InChI=1S/C5H10/c1-2-4-5-3-1/h1-5H2
IUPAC Standard InChIKey: RGSFGYAAUTVSQA-UHFFFAOYSA-N
CAS Registry Number: 287-92-3
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: Pentamethylene; UN 1146
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Gas phase ion energetics data

Go To: Top, References, Notes

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

Data compiled as indicated in comments:
B - John E. Bartmess
LL - Sharon G. Lias and Joel F. Liebman
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)	10.33 ± 0.15	eV	N/A	N/A	L

Ionization energy determinations

IE (eV)	Method	Reference	Comment
9.83 ± 0.05	EI	Holmes and Lossing, 1991	LL
10.35	PI	Traeger, 1986	LBLHLM
10.33 ± 0.15	EQ	Mautner(Meot-Ner), Sieck, et al., 1981	LLK
10.3 ± 0.1	PE	Bieri, Burger, et al., 1977	LLK
10.55 ± 0.03	PE	Rang, Paldoia, et al., 1974	LLK
10.54 ± 0.05	EI	Puttemans, 1974	LLK
10.48	PE	Puttemans, 1974	LLK
10.40	PE	Ikuta, Yoshihara, et al., 1973	LLK
10.49	EI	Lossing, 1972	LLK
10.91 ± 0.07	EI	Gross and Wilkins, 1971	LLK
10.50 ± 0.01	PE	Praet and Delwiche, 1970	RDSH
10.49	PI	Dewar and Worley, 1969	RDSH
10.53 ± 0.05	PE	Watanabe, Nakayama, et al., 1962	RDSH
11.01	PE	Kimura, Katsumata, et al., 1981	Vertical value; LLK
10.7 ± 0.1	PE	Bieri, Burger, et al., 1977	Vertical value; LLK
10.5	PE	Batich, Heilbronner, et al., 1974	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
C₃H₆⁺	11.22 ± 0.04	C₂H₄	PI	Brand and Baer, 1984	LBLHLM
C₃H₆⁺	11.45	C₂H₄	EI	Puttemans, 1974	LLK
C₃H₆⁺	11.74 ± 0.07	C₂H₄	EI	Gross and Wilkins, 1971	LLK
C₄H₇⁺	11.08	CH₃	PI	Traeger, 1986	LBLHLM
C₄H₇⁺	11.15 ± 0.03	CH₃	PI	Brand and Baer, 1984	LBLHLM
C₄H₇⁺	11.14	CH₃	EI	Brand and Baer, 1984	LBLHLM
C₄H₇⁺	11.14	CH₃	EI	Lossing, 1972	LLK
C₄H₇⁺	11.36 ± 0.08	CH₃	EI	Gross and Wilkins, 1971	LLK

De-protonation reactions

C₅H₉^- + = Cyclopentane

By formula: C₅H₉^- + H⁺ = C₅H₁₀

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	416.1 ± 2.0	kcal/mol	Bran	DePuy, Gronert, et al., 1989	gas phase; B
Δ_rH°	418.3 ± 2.0	kcal/mol	Bran	Peerboom, Rademaker, et al., 1992	gas phase; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	407.4 ± 2.1	kcal/mol	H-TS	DePuy, Gronert, et al., 1989	gas phase; B
Δ_rG°	409.6 ± 2.1	kcal/mol	H-TS	Peerboom, Rademaker, et al., 1992	gas phase; B

References

Go To: Top, Gas phase ion energetics data, Notes

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]

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]

Mautner(Meot-Ner), Sieck, et al., 1981
Mautner(Meot-Ner), M.; Sieck, L.W.; Ausloos, P., Ionization of normal alkanes: Enthalpy, entropy, structural, and isotope effects, J. Am. Chem. Soc., 1981, 103, 5342. [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]

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]

Puttemans, 1974
Puttemans, J.P., Ionisation de cycloalcanes (C₅ a C₁₂) en spectroscopie photoelectronique et par impact electronique, Ing. Chim. (Brussels), 1974, 56, 64. [all data]

Ikuta, Yoshihara, et al., 1973
Ikuta, S.; Yoshihara, K.; Shiokawa, T.; Jinno, M.; Yokoyama, Y.; Ikeda, S., Photoelectron spectroscopy of cyclohexane, cyclopentane, and some related compounds, Chem. Lett., 1973, 1237. [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]

Praet and Delwiche, 1970
Praet, M.-T.; Delwiche, J., Ionization energies of some cyclic molecules, Chem. Phys. Lett., 1970, 5, 546. [all data]

Dewar and Worley, 1969
Dewar, M.J.S.; Worley, S.D., Photoelectron spectra of molecules. I. Ionization potentials of some organic molecules and their interpretation, J. Chem. Phys., 1969, 50, 654. [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]

Kimura, Katsumata, et al., 1981
Kimura, K.; Katsumata, S.; Achiba, Y.; Yamazaki, T.; Iwata, S., Ionization energies, Ab initio assignments, and valence electronic structure for 200 molecules in Handbook of HeI Photoelectron Spectra of Fundamental Organic Compounds, Japan Scientific Soc. Press, Tokyo, 1981. [all data]

Batich, Heilbronner, et al., 1974
Batich, C.; Heilbronner, E.; Rommel, E.; Semmelhack, M.F.; Foos, J.S., Equivalence of the energy gaps {DELTA}I(1,2) and {DELTA}E(1,2) between corresponding bands in the photoelectron (I) and electronic absorption (E) spectra of spiro[4.4]nonatetraene. An amusing consequence of spiroconjugation, J. Am. Chem. Soc., 1974, 96, 7662. [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]

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]

Peerboom, Rademaker, et al., 1992
Peerboom, R.A.L.; Rademaker, G.J.; Dekoning, L.J.; Nibbering, N.M.M., Stabilization of Cycloalkyl Carbanions in the Gas Phase, Rapid Commun. Mass Spectrom., 1992, 6, 6, 394, https://doi.org/10.1002/rcm.1290060608 . [all data]

Notes

Go To: Top, Gas phase ion energetics data, References

Symbols used in this document:

AE Appearance energy

IE (evaluated) Recommended ionization energy

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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AE	Appearance energy
IE (evaluated)	Recommended ionization energy
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions