Cycloheptane
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| Names | |||
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| Preferred IUPAC name
Cycloheptane | |||
| Identifiers | |||
3D model (JSmol)
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| ChEMBL | |||
| ChemSpider | |||
| ECHA InfoCard | 100.005.483 | ||
| EC Number |
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PubChem CID
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| UNII | |||
| UN number | 2241 | ||
CompTox Dashboard (EPA)
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| Properties | |||
| C7H14 | |||
| Molar mass | 98.189 g·mol−1 | ||
| Appearance | colorless oily liquid | ||
| Density | 0.811 g/cm3[1] | ||
| Melting point | −8 °C (18 °F; 265 K)[4] | ||
| Boiling point | 118.4 °C (245.1 °F; 391.5 K)[5] | ||
| Critical point (T, P) | 604.2 K (331.1 °C; 627.9 °F), 38.2 bar (3,820 kPa)[2] | ||
| negligible | |||
| Solubility in ethanol | Very soluble | ||
| Solubility in diethyl ether | Very soluble | ||
| Solubility in benzene | Soluble | ||
| Solubility in chloroform | Soluble | ||
| log P | 4.0 | ||
Henry's law
constant (kH) |
1.1×10−4[3] | ||
Refractive index (nD)
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1.4436 | ||
| Thermochemistry[4][8] | |||
Heat capacity (C)
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Std molar
entropy (S⦵298) |
242.55 J·mol–1·K–1 | ||
Std enthalpy of
formation (ΔfH⦵298) |
−156.4 kJ⋅mol−1 | ||
Std enthalpy of
combustion (ΔcH⦵298) |
−4598.9 kJ⋅mol−1 | ||
Enthalpy of vaporization (ΔfHvap)
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38.5 kJ⋅mol−1 | ||
| Hazards | |||
| GHS labelling:[1] | |||
| Danger | |||
| H225, H304 | |||
| P210, P233, P240, P241, P242, P243, P280, P301+P310, P303+P361+P353, P331, P370+P378, P403+P235, P405, P501 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | 6 °C (43 °F; 279 K)[5] | ||
| Explosive limits | 1.1% (lower) [5] | ||
| Related compounds | |||
Related cycloalkanes
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
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Cycloheptane, also known as suberane,[10] is an organic compound, which belongs to the group of cycloalkanes. The compound can occur in different conformers.
Production
Cycloheptane occurs naturally in petroleum and can be extracted from it. It is synthesized by a Clemmensen reduction from cycloheptanone.[11]
Properties
Cycloheptane is a colorless liquid with a mild, aromatic odor. According to the Antoine equation, the vapor pressure function is given by log10(P) = A−B/T+C (P in bar, T in kelvins) with A = 3.97710, B = 1330.402 and C = −56.946 in the temperature range from 341.3 to 432.2 K (68.2 to 159.1 °C; 154.7 to 318.3 °F).[4]
In the solid phase, cycloheptane occurs in four polymorphic forms.[4][12] The transformation temperatures for the conversion from form IV to form III are 138 °C (280 °F), from form III to form II −75 °C (−103 °F) and from form II to form I −61 °C (−78 °F).[4] Form I melts at −8 °C (18 °F).[4]
| Property | Type | Value [Unit] | Note |
|---|---|---|---|
| Triple point | Ttriple | 265.12 K (−8.03 °C; 17.55 °F)[4] | |
| Critical volume | Vc | 0.53 L/mol[2] | |
| Critical density | ρc | 2.83 mol/L[2] |
Chemical properties
Cycloheptane can be thermally rearranged to methylcyclohexane in the presence of aluminum trichloride.
Functionalization can be achieved by chlorination with N-chlorosuccinimide.[13]
The compound is flammable and forms flammable vapour-air mixtures with air.[5]
Conformation
Cycloheptane is not a flat molecule, because that would give C-C-C bond angles much greater than the tetrahedral angle of around 109.5°. Instead it is puckered and three-dimensional. One can ask the question of what conformations would have the same angle everywhere (near 109.5°) and all bond lengths equal. If we think of an open chain of seven bonds, there are five dihedral angles that can be chosen, for the sequences (1,2,3,4), (2,3,4,5), and so on. The last bond though should end where the first began, and should form the correct angle with the first bond. This imposes four constraints, but we have five dihedral angles to play with, so there is one degree of freedom. It turns out that there are two continua of solutions. One is a circular series of fourteen "boat" conformations interspersed with "twist-boat" conformations, and the other is a circular series of fourteen "chair" conformations interspersed with "twist-chair" conformations. The boat and chair conformations have mirror symmetry, while the twist-boat and twist-chair have two-fold rotational symmetry. Conformations between boat and twist-boat or between chair and twist-chair have no symmetry. The passage along the continuum boat→twist-boat→boat→twist-boat→boat constitutes a pseudorotation, as does chair→twist-chair→chair→twist-chair→chair.[14]
Uses
Cycloheptane can be used as a non-polar solvent. In organic synthesis, the cycloheptyl functional groups can be introduced into organic molecules, e.g. pharmaceutical active ingredients, after functionalization.
Hazards
An irritating effect on the eyes and respiratory tract is mentioned in the literature. The toxic effect is more comparable to that of methylcyclohexane, which only slightly irritates the mucous membranes. Animal experiments showed only a slight irritating effect on the skin. Systemically, cycloheptane has a depressant effect on the central nervous system.[5]
References
- ^ a b Sigma-Aldrich Co., Cycloheptane.
- ^ a b c Daubert, Thomas E. (1996-01-01). "Vapor−Liquid Critical Properties of Elements and Compounds. 5. Branched Alkanes and Cycloalkanes". Journal of Chemical & Engineering Data. 41 (3): 365–372. doi:10.1021/je9501548. ISSN 0021-9568.
- ^ Sander, Rolf (6 October 2023). "Compilation of Henry's law constants (version 5.0.0) for water as solvent". Atmospheric Chemistry and Physics. 23 (19): 11043. doi:10.5194/acp-23-10901-2023.
- ^ a b c d e f g Finke, H. L.; Scott, D. W.; Gross, M. E.; Messerly, J. F.; Waddington, Guy (1956). "Cycloheptane, Cycloöctane and 1,3,5-Cycloheptatriene. Low Temperature Thermal Properties, Vapor Pressure and Derived Chemical Thermodynamic Properties". Journal of the American Chemical Society. 78 (21): 5469–5476. Bibcode:1956JAChS..78.5469F. doi:10.1021/ja01602a003. ISSN 0002-7863.
- ^ a b c d e "Cycloheptan". gestis.dguv.de (in German). Retrieved 2025-02-05.
- ^ Fortier, Jean-Luc; D'arcy, Patrick J.; Benson, George C. (1979). "Heat capacities of binary cycloalkane mixtures at 298.15 K". Thermochimica Acta. 28 (1). Elsevier BV: 37–43. Bibcode:1979TcAc...28...37F. doi:10.1016/0040-6031(79)87005-7. ISSN 0040-6031.
- ^ Dorofeeva, O. V.; Gurvich, L. V.; Jorish, V. S. (1986-04-01). "Thermodynamic Properties of Twenty-One Monocyclic Hydrocarbons". Journal of Physical and Chemical Reference Data. 15 (2): 437–464. Bibcode:1986JPCRD..15..437D. doi:10.1063/1.555773. ISSN 0047-2689.
- ^ Spitzer, Ralph; Huffman, Hugh M. (1947). "The Heats of Combustion of Cyclopentane, Cyclohexane, Cycloheptane and Cyclooctane". Journal of the American Chemical Society. 69 (2): 211–213. Bibcode:1947JAChS..69..211S. doi:10.1021/ja01194a006. ISSN 0002-7863. PMID 20292425.
- ^ "SDS - Cycloheptane". www.thermofisher.com. ThermoFisher Scientific. 18 December 2025. p. 3. Retrieved 26 January 2026.
- ^ "DNB, Katalog der Deutschen Nationalbibliothek" (in German). Deutsche Nationalbibliothek. 2024-12-06. Retrieved 2025-02-06.
- ^ Communications, EBCONT. "Cycloheptan". RÖMPP, Thieme (in German). Retrieved 2025-02-05.
- ^ Domalski, Eugene S.; Hearing, Elizabeth D. (1996-01-01). "Heat Capacities and Entropies of Organic Compounds in the Condensed Phase. Volume III". Journal of Physical and Chemical Reference Data. 25 (1): 1. Bibcode:1996JPCRD..25....1D. doi:10.1063/1.555985. ISSN 0047-2689.
- ^ Buu-Hoï, Ng. Ph.; Demerseman, P. (1953). "Halogenation of Saturated Compounds with N-Chloro-And N-Bromo-Succinimide". The Journal of Organic Chemistry. 18 (6): 649–652. doi:10.1021/jo01134a005. ISSN 0022-3263.
- ^ Dragojlovic, V. (2015). "Conformational analysis of cycloalkanes". ChemTexts. 1 (14): 15. Bibcode:2015ChTxt...1...14D. doi:10.1007/s40828-015-0014-0.