Cycloheptane

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Structural formula
Structural formula of cycloheptane
General
Surname Cycloheptane
other names

Heptamethylene

Molecular formula C 7 H 14
Brief description

colorless liquid

External identifiers / databases
CAS number 291-64-5
EC number 206-030-2
ECHA InfoCard 100.005.483
PubChem 9265
ChemSpider 8908
Wikidata Q423957
properties
Molar mass 98.19 g mol −1
Physical state

liquid

density

0.81 g cm −3

Melting point

−8 ° C

boiling point

119 ° C

Vapor pressure
  • 22.3 h Pa (20 ° C)
  • 37.2 hPa (30 ° C)
  • 60.8 hPa (40 ° C)
  • 95.0 hPa (50 ° C)
solubility
  • very bad in water (30 mg l −1 at 25 ° C)
  • Easily soluble in ethanol and diethyl ether
Refractive index

1.4436 (20 ° C)

safety instructions
GHS labeling of hazardous substances
02 - Highly / extremely flammable 08 - Dangerous to health

danger

H and P phrases H: 225-304
P: 210-301 + 310-331
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Cycloheptane is an organic compound that belongs to the group of substances called cycloalkanes . The connection can occur in various conformers .

Extraction and presentation

Cycloheptane occurs naturally in petroleum and can be extracted from it. A synthesis takes place via a Clemmensen reduction from cycloheptanone .

properties

Physical Properties

Cycloheptane is a colorless liquid with a mild, aromatic odor. The boiling point is 119 ° C at normal pressure . The heat of vaporization is 38.5 kJ mol −1 . According to Antoine, the vapor pressure function results according to log 10 (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.

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

Compilation of the most important thermodynamic properties
property Type Value [unit] Remarks
Standard enthalpy of formation Δ f H 0 liquid −156.4 kJ mol −1
Standard entropy S 0 liquid 242.55 J mol −1 K −1 as a liquid
Enthalpy of combustion Δ c H 0 liquid −4598.9 kJ mol −1
Heat capacity c p 180.614 J mol −1 K −1 (25 ° C)
132.0 J mol −1 K −1 (25 ° C)
as a liquid
as a gas
Triple point T triple 265.12 K
Critical temperature T c 604.2 K
Critical pressure p c 38.2 bar
Critical volume V c 0.353 l mol −1
Critical density ρ c 2.83 mol·l −1

Chemical properties

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

Rearrangement of cycloheptane to methylcyclohexane

Functionalization can take place by chlorination with N -chlorosuccinimide .

Chlorination of cycloheptane using N-chlorosuccinimide

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

use

Cycloheptane can be used as a non-polar solvent. In organic synthesis, after functionalization, the cycloheptyl function can be converted into organic molecules such. B. pharmaceutical active ingredients are introduced.

Health hazards

An irritant effect on the eyes and respiratory tract is mentioned in the literature. The toxic effect is more comparable to that of methylcyclohexane , which only weakly irritates the mucous membranes. In animal experiments, there was only a slight irritative effect with regard to skin irritation. Systemically, cycloheptane has a depressive effect on the central nervous system .

Individual evidence

  1. a b c d e f g h i j k l m n o p Entry on cycloheptane in the GESTIS substance database of the IFA , accessed on March 29, 2018(JavaScript required) .
  2. ^ Brockhaus ABC chemistry. FA Brockhaus Verlag, Leipzig 1965, p. 1587.
  3. David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-126.
  4. Entry on cycloheptane. In: Römpp Online . Georg Thieme Verlag, accessed on June 7, 2014.
  5. a b c d e f g H. L. Finke, DW Scott, ME Gross, JF Messerly, G. Waddington: Cycloheptane, Cyclooctane and 1,3,5-Cycloheptatriene . Low Temperature Thermal Properties, Vapor Pressure and Derived Chemical Thermodynamic Properties. In: J. Am. Chem. Soc. 78, 1956, pp. 5469-5476. doi: 10.1021 / ja01602a003 .
  6. ES Domalski, ED Hearing: Heat Capacities and Entropies of Organic Compounds in the Condensed phase. Volume III. In: J. Phys. Chem. Ref. Data . 25, 1996, pp. 1-525. doi: 10.1063 / 1.555985 .
  7. a b R. Spitzer, HM Huffman: The heats of combustion of cyclopentane , cyclohexane , cycloheptane and cyclooctanes . In: J. Am. Chem. Soc. 69, 1947, pp. 211-213. doi: 10.1021 / ja01194a006 .
  8. J.-L. Fortier, PJ D'Arcy, GC Benson: Heat capacities of binary cycloalkane mixtures at 298.15 K. In: Thermochim. Acta . 28, 1979, pp. 37-43, doi: 10.1016 / 0040-6031 (79) 87005-7 .
  9. ^ OV Dorofeeva: Thermodynamic properties of twenty-one monocyclic hydrocarbons. ( Memento of March 4, 2016 in the Internet Archive ) In: J. Phys. Chem. Ref. Data . 15, 1986, pp. 437-464. doi: 10.1063 / 1.555773 .
  10. a b c d T. E. Daubert: Vapor-Liquid Critical Properties of Elements and Compounds. 5. Branched Alkanes and Cycloalkanes. In: J. Chem. Eng. Data . 41, 1996, pp. 365-372. doi: 10.1021 / je9501548 .
  11. ^ S. Hauptmann, J. Graefe, H. Remane: Textbook of organic chemistry. German publishing house for basic industry, Leipzig 1980, p. 207.
  12. Ph. Buu-Hou, P. Demerseman: Halogenation of Saturated Compounds with N-Chloro- and N-Bromo-Succinimide. In: J. Org. Chem. 18, 1953, pp. 649-652. doi: 10.1021 / jo01134a005 .
  13. E. Brandes, W. Möller: Safety-related parameters. Volume 1: Flammable Liquids and Gases. Wirtschaftsverlag NW - Verlag für neue Wissenschaft, Bremerhaven 2003.

Web links

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