Methylcyclohexane

Last updated
Methylcyclohexane
Methylcyclohexane-2D-skeletal.png
Methylcyclohexane-3D-balls.png
Names
Preferred IUPAC name
Methylcyclohexane
Other names
Hexahydrotoluene
Cyclohexylmethane
Toluene hexahydride
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.003.296 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/C7H14/c1-7-5-3-2-4-6-7/h7H,2-6H2,1H3 Yes check.svgY
    Key: UAEPNZWRGJTJPN-UHFFFAOYSA-N Yes check.svgY
  • 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
AppearanceColourless 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:
GHS-pictogram-flamme.svg GHS-pictogram-exclam.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
Danger
H225, H302, H304, H315, H336, H410 [2]
P210, P235, P301+P310, P331, P370+P378, P403 [2]
NFPA 704 (fire diamond)
NFPA 704.svgHealth 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).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

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.

Contents

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

Methylcyclohexane, as a component of a mixture, 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. MeC6H11toPhMe.png
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.

It is also one of a host of substances in jet fuel surrogate blends, e.g., for Jet A fuel. [11] [12]

Solvent

Methylcyclohexane is used as an organic solvent, with properties similar to related saturated hydrocarbons such as heptane. [13] 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". [14] Note, while methylcyclohexane is a substructure of 4-methylcyclohexanemethanol (MCHM), it is distinct in its physical, chemical, and biological (ecologic, metabolic, and toxicologic) properties. [15]

Related Research Articles

<span class="mw-page-title-main">Toluene</span> Chemical compound

Toluene, also known as toluol, is a substituted aromatic hydrocarbon with the chemical formula C6H5CH3, often abbreviated as PhCH3, where Ph stands for the phenyl group. It is a colorless, water-insoluble liquid with the odor associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a methyl group (CH3) attached to a phenyl group by a single bond. As such, its systematic IUPAC name is methylbenzene. Toluene is predominantly used as an industrial feedstock and a solvent.

<span class="mw-page-title-main">Xylene</span> Organic compounds with the formula (CH3)2C6H4

In organic chemistry, xylene or xylol are any of three organic compounds with the formula (CH3)2C6H4. They are derived from the substitution of two hydrogen atoms with methyl groups in a benzene ring; which hydrogens are substituted determines which of three structural isomers results. It is a colorless, flammable, slightly greasy liquid of great industrial value.

Nitromethane, sometimes shortened to simply "nitro", is an organic compound with the chemical formula CH
3
NO
2
. It is the simplest organic nitro compound. It is a polar liquid commonly used as a solvent in a variety of industrial applications such as in extractions, as a reaction medium, and as a cleaning solvent. As an intermediate in organic synthesis, it is used widely in the manufacture of pesticides, explosives, fibers, and coatings. Nitromethane is used as a fuel additive in various motorsports and hobbies, e.g. Top Fuel drag racing and miniature internal combustion engines in radio control, control line and free flight model aircraft.

Cyclohexane is a cycloalkane with the molecular formula C6H12. Cyclohexane is non-polar. Cyclohexane is a colourless, flammable liquid with a distinctive detergent-like odor, reminiscent of cleaning products. Cyclohexane is mainly used for the industrial production of adipic acid and caprolactam, which are precursors to nylon.

<span class="mw-page-title-main">Butadiene</span> Chemical compound

1,3-Butadiene is the organic compound with the formula CH2=CH-CH=CH2. It is a colorless gas that is easily condensed to a liquid. It is important industrially as a precursor to synthetic rubber. The molecule can be viewed as the union of two vinyl groups. It is the simplest conjugated diene.

Cyclohexene is a hydrocarbon with the formula (CH2)4C2H2. It is an example of a cycloalkene. At room temperature, cyclohexene is a colorless liquid with a sharp odor. Among its uses, it is an intermediate in the commercial synthesis of nylon.

<span class="mw-page-title-main">Steric effects</span> Geometric aspects of ions and molecules affecting their shape and reactivity

Steric effects arise from the spatial arrangement of atoms. When atoms come close together there is generally a rise in the energy of the molecule. Steric effects are nonbonding interactions that influence the shape (conformation) and reactivity of ions and molecules. Steric effects complement electronic effects, which dictate the shape and reactivity of molecules. Steric repulsive forces between overlapping electron clouds result in structured groupings of molecules stabilized by the way that opposites attract and like charges repel.

Cyclopentane (also called C pentane) is a highly flammable alicyclic hydrocarbon with chemical formula C5H10 and CAS number 287-92-3, consisting of a ring of five carbon atoms each bonded with two hydrogen atoms above and below the plane. It occurs as a colorless liquid with a petrol-like odor. Its freezing point is −94 °C and its boiling point is 49 °C. Cyclopentane is in the class of cycloalkanes, being alkanes that have one or more carbon rings. It is formed by cracking cyclohexane in the presence of alumina at a high temperature and pressure.

<span class="mw-page-title-main">Cyclohexane conformation</span> Structures of cyclohexane

Cyclohexane conformations are any of several three-dimensional shapes adopted by molecules of cyclohexane. Because many compounds feature structurally similar six-membered rings, the structure and dynamics of cyclohexane are important prototypes of a wide range of compounds.

<span class="mw-page-title-main">Conformational isomerism</span> Different molecular structures formed only by rotation about single bonds

In chemistry, conformational isomerism is a form of stereoisomerism in which the isomers can be interconverted just by rotations about formally single bonds. While any two arrangements of atoms in a molecule that differ by rotation about single bonds can be referred to as different conformations, conformations that correspond to local minima on the potential energy surface are specifically called conformational isomers or conformers. Conformations that correspond to local maxima on the energy surface are the transition states between the local-minimum conformational isomers. Rotations about single bonds involve overcoming a rotational energy barrier to interconvert one conformer to another. If the energy barrier is low, there is free rotation and a sample of the compound exists as a rapidly equilibrating mixture of multiple conformers; if the energy barrier is high enough then there is restricted rotation, a molecule may exist for a relatively long time period as a stable rotational isomer or rotamer. When the time scale for interconversion is long enough for isolation of individual rotamers, the isomers are termed atropisomers. The ring-flip of substituted cyclohexanes constitutes another common form of conformational isomerism.

In chemistry, a molecule experiences strain when its chemical structure undergoes some stress which raises its internal energy in comparison to a strain-free reference compound. The internal energy of a molecule consists of all the energy stored within it. A strained molecule has an additional amount of internal energy which an unstrained molecule does not. This extra internal energy, or strain energy, can be likened to a compressed spring. Much like a compressed spring must be held in place to prevent release of its potential energy, a molecule can be held in an energetically unfavorable conformation by the bonds within that molecule. Without the bonds holding the conformation in place, the strain energy would be released.

<span class="mw-page-title-main">Biphenyl</span> Chemical compound

Biphenyl is an organic compound that forms colorless crystals. Particularly in older literature, compounds containing the functional group consisting of biphenyl less one hydrogen may use the prefixes xenyl or diphenylyl.

<span class="mw-page-title-main">Decalin</span> Chemical compound

Decalin, a bicyclic organic compound, is an industrial solvent. A colorless liquid with an aromatic odor, it is used as a solvent for many resins or fuel additives.

Aromatization is a chemical reaction in which an aromatic system is formed from a single nonaromatic precursor. Typically aromatization is achieved by dehydrogenation of existing cyclic compounds, illustrated by the conversion of cyclohexane into benzene. Aromatization includes the formation of heterocyclic systems.

In organic chemistry, a ring flip is the interconversion of cyclic conformers that have equivalent ring shapes that results in the exchange of nonequivalent substituent positions. The overall process generally takes place over several steps, involving coupled rotations about several of the molecule's single bonds, in conjunction with minor deformations of bond angles. Most commonly, the term is used to refer to the interconversion of the two chair conformers of cyclohexane derivatives, which is specifically referred to as a chair flip, although other cycloalkanes and inorganic rings undergo similar processes.

<span class="mw-page-title-main">Anomeric effect</span> Tendency of some substituents on a cyclohexane ring to prefer axial orientation

In organic chemistry, the anomeric effect or Edward-Lemieux effect is a stereoelectronic effect that describes the tendency of heteroatomic substituents adjacent to a heteroatom within a cyclohexane ring to prefer the axial orientation instead of the less-hindered equatorial orientation that would be expected from steric considerations. This effect was originally observed in pyranose rings by J. T. Edward in 1955 when studying carbohydrate chemistry.

<span class="mw-page-title-main">Dimethoxymethane</span> Chemical compound

Dimethoxymethane, also called methylal, is a colorless flammable liquid with a low boiling point, low viscosity and excellent dissolving power. It has a chloroform-like odor and a pungent taste. It is the dimethyl acetal of formaldehyde. Dimethoxymethane is soluble in three parts water and miscible with most common organic solvents.

A-values are numerical values used in the determination of the most stable orientation of atoms in a molecule, as well as a general representation of steric bulk. A-values are derived from energy measurements of the different cyclohexane conformations of a monosubstituted cyclohexane chemical. Substituents on a cyclohexane ring prefer to reside in the equatorial position to the axial. The difference in Gibbs free energy (ΔG) between the higher energy conformation and the lower energy conformation is the A-value for that particular substituent.

1,2,3-Trimethylbenzene is an organic compound with the chemical formula C6H3(CH3)3. Classified as an aromatic hydrocarbon, it is a flammable colorless liquid. It is nearly insoluble in water but soluble in organic solvents.

Fuel surrogates are mixtures of one or more simple fuels that are designed to emulate either the physical properties or combustion properties of a more complex fuel. While surrogate mixtures can demonstrate more than one characteristic of the desired fuel, more often than not different components are required in order to emulate the wide variety of properties that are of interest to researchers. Jet fuel is an example of a fuel requiring a surrogate for experimental research and numerical modelling due to its complexity and high content variability from one batch to the next. Neat hydrocarbon jet fuel surrogate components include decane, dodecane, methylcyclohexane, and toluene. Gasoline surrogate components include n-heptane and iso-octane. Hexadecane is a diesel surrogate component. Biodiesel surrogate components include methyl butyrate and methyl decanoate.

References

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  2. 1 2 3 4 5 6 7 8 Sigma-Aldrich Co., Methylcyclohexane. Retrieved on 2022-03-17.
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  4. 1 2 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.
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