Methylcyclohexane

Methylcyclohexane
Names
Preferred IUPAC name
Methylcyclohexane
Other names
Hexahydrotoluene
Cyclohexylmethane
Toluene hexahydride
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.003.296 Edit this at Wikidata
UNII
  • InChI=1S/C7H14/c1-7-5-3-2-4-6-7/h7H,2-6H2,1H3 checkY
    Key: UAEPNZWRGJTJPN-UHFFFAOYSA-N checkY
  • InChI=1/C7H14/c1-7-5-3-2-4-6-7/h7H,2-6H2,1H3
    Key: UAEPNZWRGJTJPN-UHFFFAOYAG
  • CC1CCCCC1
Properties
C7H14
Molar mass 98.189 g·mol−1
Appearance Colourless liquid
Odor faint, benzene-like[1]
Density 0.77 g/cm3
Melting point −126.3 °C (−195.3 °F; 146.8 K)
Boiling point 101 °C (214 °F; 374 K)
0.014 g/L at 25 °C[2]
Vapor pressure 37 mmHg (20°C)[1]

49.3 hPa at 20.0 °C
110.9 hPa at 37.7 °C[2]

-78.91·10−6 cm3/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 severe fire hazard
GHS labelling:
GHS02: FlammableGHS07: Exclamation markGHS08: Health hazardGHS09: Environmental hazard
Danger
H225, H302, H304, H315, H336, H410[2]
P210, P235, P301+P310, P331, P370+P378, P403[2]
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
3
0
Flash point −4 °C (25 °F; 269 K)[2] Closed cup
283 °C (541 °F; 556 K)[2]
Explosive limits 1.2%-6.7%[1][2]
Lethal dose or concentration (LD, LC):
2250 mg/kg (mouse, oral)[3]
10172 ppm (mouse, 2 hr)
10,000-12,500 ppm (mouse, 2 hr)
15227 ppm (rabbit, 1 hr)[3]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 500 ppm (2000 mg/m3)[1]
REL (Recommended)
 TWA 400 ppm (1600 mg/m3)[1]
IDLH (Immediate danger)
 1200 ppm[1]
Safety data sheet (SDS) [2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Methylcyclohexane (cyclohexylmethane) is an organic compound with the molecular formula is CH3C6H11. Classified as saturated hydrocarbon, it is a colourless liquid with a faint odor.

Methylcyclohexane is used as a solvent. It is mainly converted in naphtha reformers to toluene.[4] A special use is in PF-1 priming fluid in cruise missiles to aid engine start-up when they run on special nonvolatile jet fuel like JP-10.[5] Methylcyclohexane is also used in some correction fluids (such as White-Out) as a solvent.

History

While researching hydrogenation of arenes with hydroiodic acid in 1876[6] as part of his doctoral dissertation[7], Felix Wreden [ru] first prepared the hydrocarbon from toluene. He determined its boiling point to be 97°C, its density at 20°C to by 0.76 g/cc and named it hexahydrotoluene.[8] It was soon identified in oil from Baku and obtained by other synthetic methods.[9]

Production and use

Most methylcyclohexane is extracted from petroleum but it can be also produced by catalytic hydrogenation of toluene:

CH3C6H5 + 3 H2 → CH3C6H11

The hydrocarbon is a minor component of automobile fuel, with its share in US gasoline varying between 0.3 and 1.7% in early 1990s[10] and 0.1 to 1% in 2011[11]. Its research and motor octane numbers are 75 and 71 respectively.[12]

As a component of a mixture, it is usually dehydrogenated to toluene, which increases the octane rating of gasoline.[4]

The conversion of methylcyclohexane to toluene is a classic aromatization reaction. This platinum (Pt)-catalyzed process is practiced on scale in the production of gasoline from petroleum.[13]

It is also one of a host of substances in jet fuel surrogate blends, e.g., for Jet A fuel.[14][15]

Solvent

Methylcyclohexane is used as an organic solvent, with properties similar to related saturated hydrocarbons such as heptane.[16] It is also a solvent in many types of correction fluids.

Structure

Methylcyclohexane is a monosubstituted cyclohexane because it has one branching via the attachment of one methyl group on one carbon of the cyclohexane ring. Like all cyclohexanes, it can interconvert rapidly between two chair conformers. The lowest energy form of this monosubstituted methylcyclohexane occurs when the methyl group occupies an equatorial rather than an axial position. This equilibrium is embodied in the concept of A value. In the axial position, the methyl group experiences steric crowding (steric strain) because of the presence of axial hydrogen atoms on the same side of the ring (known as the 1,3-diaxial interactions). There are two such interactions, with each pairwise methyl/hydrogen combination contributing approximately 7.61 kJ/mol of strain energy. The equatorial conformation experiences no such interaction, and so it is the energetically favored conformation.

Flammability and toxicity

Methylcyclohexane is flammable.

Furthermore, it is considered "very toxic to aquatic life".[17] Note, while methylcyclohexane is a substructure of 4-methylcyclohexanemethanol (MCHM), it is distinct in its physical, chemical, and biological (ecologic, metabolic, and toxicologic) properties.[18]

References

  1. ^ a b c d e f NIOSH Pocket Guide to Chemical Hazards. "#0406". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ a b c d e f g h Sigma-Aldrich Co., Methylcyclohexane. Retrieved on 2022-03-17.
  3. ^ a b "Methylcyclohexane". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  4. ^ a b M. Larry Campbell. "Cyclohexane" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2012. doi:10.1002/14356007.a08_209.pub2
  5. ^ Martel, Charles R. (1987). Military Jet Fuels, 1944-1987. Aero Propulsion Laboratory, Air Force Wright Aeronautical Laboratories, Air Force Systems Command, United States Air Force. p. 10.
  6. ^ "Феликс Романович Вреден - Биография". physchem.chimfak.sfedu.ru (in Russian). Retrieved 2024-12-03.
  7. ^ О гидрогенизации монобензоловых углеводородов О продуктах гидрогенизации и о строении нафталина - Соч. Ф. Вредена (in Russian). 1876.
  8. ^ Wreden, F. (1877). "Ueber die Hydrogenisation des Benzols und seiner Homologen". Justus Liebigs Annalen der Chemie (in German). 187 (2–3): 153–167. doi:10.1002/jlac.18771870202. ISSN 1099-0690.
  9. ^ Richter, Victor von (1899). Victor Von Richter's Organic Chemistry: Or, Chemistry of the Carbon Compounds. P. Blakiston's son & Company. p. 292.
  10. ^ Doskey, Paul V.; Porter, Joseph A.; Scheff, Peter A. (November 1992). "Source Fingerprints for Volatile Non-Methane Hydrocarbons". Journal of the Air & Waste Management Association. 42 (11): 1437–1445. doi:10.1080/10473289.1992.10467090. ISSN 1047-3289.
  11. ^ "Hydrocarbon Composition of Gasoline Vapor Emissions from Enclosed Fuel Tanks". nepis.epa.gov. United States Environmental Protection Agency. 2011.
  12. ^ Scherzer, Julius (1990). Octane-Enhancing Zeolitic FCC Catalysts: Scientific and Technical Aspects. CRC Press. p. 9. ISBN 978-0-8247-8399-0.
  13. ^ Gary, J.H.; Handwerk, G.E. (1984). Petroleum Refining Technology and Economics (2nd ed.). Marcel Dekker, Inc. ISBN 0-8247-7150-8.
  14. ^ Tim Edwards, Meredith Colket, Nick Cernansky, Fred Dryer, Fokion Egolfopoulos, Dan Friend, Ed Law, Dave Lenhert, Peter Lindstedt, Heinz Pitsch, Adel Sarofim, Kal Seshadri, Mitch Smooke, Wing Tsang & Skip Williams, 2007, AIAA2007-770: Development of an Experimental Database and Kinetic Models for Surrogate Jet Fuels, 45th AIAA Aerospace Sciences Meeting and Exhibit, 8-11 January 2007, Reno, Nevada, DOI 10.2514/6.2007-770, see [1], accessed 27 May 2014.
  15. ^ Meredith Colket, Tim Edwards, Fred Dryer, Skip Williams, Nicholas Cernansky, David Miller, Fokion Egolfopoulos, Frederick Dryer & Josette Bellan, 2008, AIAA 2008-972: Identification of Target Validation Data for Development of Surrogate Jet Fuels, 46th AIAA Aerospace Sciences Meeting and Exhibit, 8-11 January 2007, Reno, Nevada, DOI 10.2514/6.2008-972, see [2], accessed 27 May 2014.
  16. ^ D. Bryce-Smith and E. T. Blues "Unsolvated n-Butylmagnesium Chloride" Org. Synth. 1967, 47, 113. doi:10.15227/orgsyn.047.0113
  17. ^ Chevron Phillips, 2014, "Material Safety Data Sheet: Methylcyclohexane (v. 1.5)", see [3], accessed 23 May 2014.
  18. ^ CDC, 2014, "Methylcyclohexane," NIOSH Pocket Guide to Chemical Hazards, see [4], accessed 27 May 2014.