Cyclohexane, 1,2-dimethyl-, cis-

Formula: C₈H₁₆
Molecular weight: 112.2126
IUPAC Standard InChI: InChI=1S/C8H16/c1-7-5-3-4-6-8(7)2/h7-8H,3-6H2,1-2H3/t7-,8+
IUPAC Standard InChIKey: KVZJLSYJROEPSQ-OCAPTIKFSA-N
CAS Registry Number: 2207-01-4
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.
Species with the same structure:
- cyclohexane, 4,5-dimethyl-, cis-
Stereoisomers:
- Cyclohexane, 1,2-dimethyl- (cis/trans)
- Cyclohexane, 1,2-dimethyl-, trans-
Other names: cis-1,2-Dimethylcyclohexane; 1,cis-2-Dimethylcyclohexane; Cyclohexane, 1,cis-2-dimethyl-; 1,2-cis-DimethyIcyclohexane; 1,2-Dimethylcyclohexane, cis; c-1,2-Dimethylcyclohexane
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Other data available:
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NIST / TRC Web Thermo Tables, professional edition (thermophysical and thermochemical data)

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Gas phase thermochemistry data

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Data compiled by: Glushko Thermocenter, Russian Academy of Sciences, Moscow

Quantity	Value	Units	Method	Reference	Comment
S°_gas	89.469	cal/mol*K	N/A	Huffman H.M., 1949

Constant pressure heat capacity of gas

C_p,gas (cal/mol*K)	Temperature (K)	Reference	Comment
9.431	50.	Thermodynamics Research Center, 1997	p=1 bar. There is an appreciable difference, mainly at high temperatures, with values estimated earlier by a method of increments [ Beckett C.W., 1947].
15.42	100.
20.26	150.
24.71	200.
32.91	273.15
36.14	298.15
36.40	300.
49.78	400.
61.97	500.
72.23	600.
80.78	700.
87.98	800.
94.10	900.
99.31	1000.
103.8	1100.
107.6	1200.
110.8	1300.
113.6	1400.
116.0	1500.
120.7	1750.
124.1	2000.
126.6	2250.
128.4	2500.
129.8	2750.
130.9	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_cH°_liquid	-1248. ± 0.43	kcal/mol	Ccb	Johnson, Prosen, et al., 1947	Corresponding Δ_fHº_liquid = -51. kcal/mol (simple calculation by NIST; no Washburn corrections)

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

3 + = Cyclohexane, 1,2-dimethyl-, cis-

By formula: 3H₂ + C₈H₁₀ = C₈H₁₆

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-46.51 ± 0.20	kcal/mol	Chyd	Dolliver, Gresham, et al., 1937	gas phase; Reanalyzed by Cox and Pilcher, 1970, Original value = -47.25 ± 0.20 kcal/mol; At 355 °K

Cyclohexane, 1,2-dimethyl-, cis- =

By formula: C₈H₁₆ = C₈H₁₆

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.6 ± 0.1	kcal/mol	Eqk	Mann, 1968	gas phase; At 593K

= Cyclohexane, 1,2-dimethyl-, cis-

By formula: C₈H₁₆ = C₈H₁₆

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1.7 ± 0.3	kcal/mol	Eqk	Anfilogova, Balenkova, et al., 1974	gas phase

Gas phase ion energetics data

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Data compiled as indicated in comments:
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron

Ionization energy determinations

IE (eV)	Method	Reference	Comment
≤9.78 ± 0.05	EI	Herzschuh and Sicker, 1981	LLK
9.90 ± 0.07	EI	Lageot, 1971	LLK
10.08 ± 0.02	EI	Natalis, 1964	RDSH

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
C₅H₉⁺	12.12 ± 0.05	?	EI	Natalis, 1964	RDSH
C₅H₁₀⁺	11.62 ± 0.08	?	EI	Natalis, 1964	RDSH
C₆H₁₀⁺	10.5 ± 0.1	2CH₃	EI	Lageot, 1971	LLK
C₆H₁₀⁺	10.62 ± 0.04	C₂H₆	EI	Natalis, 1964	RDSH
C₆H₁₁⁺	11.06 ± 0.02	C₂H₅	EI	Natalis, 1964	RDSH
C₆H₁₂⁺	11.17 ± 0.02	C₂H₄	EI	Natalis, 1964	RDSH
C₇H₁₃⁺	10.63 ± 0.05	CH₃	EI	Herzschuh and Sicker, 1981	LLK
C₇H₁₃⁺	10.83 ± 0.05	C₂H₅	EI	Herzschuh and Sicker, 1981	LLK
C₇H₁₃⁺	10.55 ± 0.05	CH₃	EI	Lageot, 1971	LLK
C₇H₁₃⁺	10.78 ± 0.02	CH₃	EI	Natalis, 1964	RDSH

References

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Huffman H.M., 1949
Huffman H.M., Low-temperature thermal data on eight C8H16 alkylcyclohexanes, J. Am. Chem. Soc., 1949, 71, 584-592. [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]

Beckett C.W., 1947
Beckett C.W., The thermodynamic properties and molecular structure of cyclohexane, methylcyclohexane, ethylcyclohexane, and seven dimethylcyclohexanes, J. Am. Chem. Soc., 1947, 69, 2488-2495. [all data]

Johnson, Prosen, et al., 1947
Johnson, W.H.; Prosen, E.J.; Rossini, F.D., Heats of combustion and isomerization of the eight C₈H₁₆ alkylcyclohexanes, J. Res. NBS, 1947, 39, 49-52. [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]

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

Mann, 1968
Mann, G., Conformation and physical data of alkanes and cyclanes. IV. Conformation energy of gauche-anticonformers, Tetrahedron, 1968, 24, 6495-65. [all data]

Anfilogova, Balenkova, et al., 1974
Anfilogova, S.N.; Balenkova, E.S.; Dmitriev, A.B., Relative stability of cis- and trans-1,2-dimethylcycloheptanes and 1,2-dimethylcyclooctanes, Neftekhimiya, 1974, 14, 673-676. [all data]

Herzschuh and Sicker, 1981
Herzschuh, R.; Sicker, A., Stereochemische einflusse auf die ionisations- und auftrittsenergien cis/trans-isomerer dimethylcycloalkane, Z. Chem., 1981, 21, 409. [all data]

Lageot, 1971
Lageot, C., Potentiel d'ionisation, potentiel d'apparition et courbes d'ionisation differentielle pour les 1-2 dimethylcyclohexanes cis et trans, Org. Mass Spectrom., 1971, 5, 839. [all data]

Natalis, 1964
Natalis, P., Etude du comportement d'isomeres geometriques sous l'impact electronique. V. Comparaison des donnees obtenues, par differentes methodes, pour les 1,2-dimethylcyclohexanes cis et trans, Bull. Soc. Chim. Belges, 1964, 73, 961. [all data]

Notes

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Symbols used in this document:

AE	Appearance energy
C_p,gas	Constant pressure heat capacity of gas
S°_gas	Entropy of gas at standard conditions
Δ_cH°_liquid	Enthalpy of combustion 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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