Cycloheptane, also known as Suberane,[1] 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.[2]

Properties

Cycloheptane is a colorless liquid with a mild, aromatic odor. The boiling point at normal pressure is 119°C.[3] The molar enthalpy of vaporization is 38.5 kJ mol−1.[4] According to the Antoine equation, the vapor pressure function is given by log10(P) = A−(B/(T+C)) (P in bar, T in K) with A = 3,97710, B = 1330,402 and C = −56,946 in the temperature range from 341.3 K to 432.2 K.[4]

In the solid phase, cycloheptane occurs in four polymorphic forms.[4][5] The transformation temperatures for the conversion from form IV to form III are −138°C, from form III to form II −75°C and from form II to form I −61°C.[4] Form I melts at −8°C.[4][3]

Compilation of the most important thermodynamic properties
Property Type Value [Unit] Note
Standard enthalpy of formation ΔfH0liquid −156,4 kJ·mol−1[6]
Standard entropy S0liquid 242,55 J·mol−1·K−1[4] as a liquid
Heat of combustion ΔcH0liquid −4598,9 kJ·mol−1[6]
Heat capacity cp 180,614 J·mol−1·K−1 (25 °C)[7]

132,0 J·mol−1·K−1 (25 °C)[8] 		as a liquid

as a gas
Triple point Ttriple 265,12 K[4]
Critical temperature Tc 604,2 K[9]
Critical pressure pc 38,2 bar[9]
Critical volume Vc 0.353 l·mol−1[9]
Critical density ρc 2,83 mol·l−1[9]

Chemical properties

Cycloheptane can be thermally rearranged to methylcyclohexane in the presence of aluminum trichloride.

Functionalization can be achieved by chlorination with N-chlorosuccinimide.[10]

The compound is flammable and forms flammable vapour-air mixtures with air.[3] The flash point is 6 °C, the lower explosion limit is 1.1 vol.%.[3]

Usage

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.[3]

Further reading

References

  1. ^ "DNB, Katalog der Deutschen Nationalbibliothek" (in German). Deutsche Nationalbibliothek. 2024-12-06. Retrieved 2025-02-06.
  2. ^ Communications, EBCONT. "Cycloheptan". RÖMPP, Thieme (in German). Retrieved 2025-02-05.
  3. ^ a b c d e "Cycloheptan". gestis.dguv.de. Retrieved 2025-02-05.
  4. ^ 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. doi:10.1021/ja01602a003. ISSN 0002-7863.
  5. ^ Domalski, Eugene S.; Hearing, Elizabeth D. (1996-01-01). "Heat Capacities and Entropies of Organic Compounds in the Condensed Phase. Volume III" (PDF). Journal of Physical and Chemical Reference Data. 25 (1): 1. doi:10.1063/1.555985. ISSN 0047-2689. Retrieved 2025-02-05.
  6. ^ a b 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. doi:10.1021/ja01194a006. ISSN 0002-7863. PMID 20292425.
  7. ^ 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. doi:10.1016/0040-6031(79)87005-7. ISSN 0040-6031.
  8. ^ 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. doi:10.1063/1.555773. ISSN 0047-2689.
  9. ^ a b c d 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.
  10. ^ 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.
Allikas: https://en.wikipedia.org/wiki/Cycloheptane
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