Cyclopropane, 1,1-dimethyl-

Formula: C₅H₁₀
Molecular weight: 70.1329
IUPAC Standard InChI: InChI=1S/C5H10/c1-5(2)3-4-5/h3-4H2,1-2H3
IUPAC Standard InChIKey: PBIJFSCPEFQXBB-UHFFFAOYSA-N
CAS Registry Number: 1630-94-0
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: Gem-Dimethylcyclopropane; 1,1-Dimethylcyclopropane
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Information on this page:
Other data available:
Data at other public NIST sites:
- Microwave spectra (on physics lab web site)
- Gas Phase Kinetics Database
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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
GT - Glushko Thermocenter, Russian Academy of Sciences, Moscow

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	-1.97 ± 0.28	kcal/mol	Ccb	Good, Moore, et al., 1974	ALS

Constant pressure heat capacity of gas

C_p,gas (cal/mol*K)	Temperature (K)	Reference	Comment
8.253	50.	Thermodynamics Research Center, 1997	p=1 bar. Selected values are lower than other statistically calculated values [ Kabo G.Y., 1973] up to 2.2 and 1.1 J/mol*K for S(T) and Cp(T), respectively.; GT
11.02	100.
14.45	150.
17.88	200.
23.43	273.15
25.423	298.15
25.571	300.
33.289	400.
39.955	500.
45.483	600.
50.105	700.
54.037	800.
57.416	900.
60.337	1000.
62.868	1100.
65.065	1200.
66.972	1300.
68.628	1400.
70.074	1500.
72.94	1750.
75.02	2000.
76.58	2250.
77.75	2500.
78.63	2750.
79.35	3000.

Condensed phase thermochemistry data

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

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_liquid	-7.97 ± 0.19	kcal/mol	Ccb	Good, Moore, et al., 1974
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_liquid	-803.86 ± 0.17	kcal/mol	Ccb	Good, Moore, et al., 1974	Corresponding Δ_fHº_liquid = -7.97 kcal/mol (simple calculation by NIST; no Washburn corrections)

Phase change data

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Data compiled as indicated in comments:
BS - Robert L. Brown and Stephen E. Stein
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DRB - Donald R. Burgess, Jr.
AC - William E. Acree, Jr., James S. Chickos

Quantity	Value	Units	Method	Reference	Comment
T_boil	295. ± 9.	K	AVG	N/A	Average of 10 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
T_fus	164. ± 1.	K	AVG	N/A	Average of 9 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
Δ_vapH°	6.0 ± 0.2	kcal/mol	E	Good, Moore, et al., 1974	ALS
Δ_vapH°	6.00	kcal/mol	N/A	Good, Moore, et al., 1974	DRB
Δ_vapH°	6.0 ± 0.2	kcal/mol	EB	Good, Moore, et al., 1974	AC

In addition to the Thermodynamics Research Center (TRC) data available from this site, much more physical and chemical property data is available from the following TRC products:

Gas phase ion energetics data

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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 C₅H₁₀⁺ (ion structure unspecified)

Ionization energy determinations

IE (eV)	Method	Reference	Comment
8.98 ± 0.05	EI	Holmes and Lossing, 1991	LL
9.1	PE	Plemenkov, Villem, et al., 1981	LLK
9.08	EI	Lossing, 1972	LLK
9.76 ± 0.02	EI	Natalis and Laune, 1964	RDSH
9.80	PE	Plemenkov, Villem, et al., 1981	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
C₃H₆⁺	11.23 ± 0.04	C₂H₄	EI	Natalis and Laune, 1964	RDSH
C₄H₇⁺	10.47	CH₃	EI	Lossing, 1972	LLK
C₄H₇⁺	11.37 ± 0.02	CH₃	EI	Natalis and Laune, 1964	RDSH

References

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Good, Moore, et al., 1974
Good, W.D.; Moore, R.T.; Osborn, A.G.; Douslin, D.R., The enthalpies of formation of ethylcyclobutane, methylenecyclobutane, and 1,1-dimethylcyclopropane, J. Chem. Thermodyn., 1974, 6, 303-310. [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]

Kabo G.Y., 1973
Kabo G.Y., Thermodynamic properties of some hydrocarbons containing three-membered rings, Vestn. Beloruss. Univ., Ser. 2, 1973, 3-6. [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]

Plemenkov, Villem, et al., 1981
Plemenkov, V.V.; Villem, Y.Y.; Villem, N.V.; Bolesov, I.G.; Surmina, L.S.; Yakushkina, N.I.; Formanovskii, A.A., Photoelectron spectra of polyalkylcyclopropenes and polyalkylcyclopropanes, Zh. Obshch. Khim., 1981, 51, 2076. [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]

Natalis and Laune, 1964
Natalis, P.; Laune, J., Etude du comportement d'isomeres geometriques sous l'impact electronique. IV. Cyclopropane, methylcyclopropane et dimethylcyclopropanes gem. cis et trans, Bull. Soc. Chim. Belges, 1964, 73, 944. [all data]

Notes

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Symbols used in this document:

AE	Appearance energy
C_p,gas	Constant pressure heat capacity of gas
T_boil	Boiling point
T_fus	Fusion (melting) point
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_vapH°	Enthalpy of vaporization at standard conditions

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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