Hexane

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Hexane
Hexane-2D-Skeletal.svg
Hexane-2D-B.png
Hexane-from-xtal-1999-at-an-angle-3D-balls.png
Hexane-3D-vdW.png
Names
Preferred IUPAC name
Hexane [1]
Other names
Sextane, [2] hexacarbane
Identifiers
3D model (JSmol)
1730733
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.003.435 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 203-777-6
1985
KEGG
MeSH n-hexane
PubChem CID
RTECS number
  • MN9275000
UNII
UN number 1208
  • InChI=1S/C6H14/c1-3-5-6-4-2/h3-6H2,1-2H3 Yes check.svgY
    Key: VLKZOEOYAKHREP-UHFFFAOYSA-N Yes check.svgY
  • CCCCCC
Properties
C6H14
Molar mass 86.178 g·mol−1
AppearanceColorless liquid
Odor Petrolic
Density 0.6606 g mL−1 [3]
Melting point −96 to −94 °C; −141 to −137 °F; 177 to 179 K
Boiling point 68.5 to 69.1 °C; 155.2 to 156.3 °F; 341.6 to 342.2 K
9.5 mg L−1
log P 3.764
Vapor pressure 17.60 kPa (at 20.0 °C)
7.6 nmol Pa−1 kg−1
UV-vis (λmax)200 nm
−74.6·10−6 cm3/mol
1.375
Viscosity 0.3 mPa·s
0.08 D
Thermochemistry
265.2 J K−1 mol−1
Std molar
entropy (S⦵298)
296.06 J K−1 mol−1
−199.4–−198.0 kJ mol−1
−4180–−4140 kJ mol−1
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Reproductive toxicity – After aspiration, pulmonary oedema, pneumonitis [4]
GHS labelling:
GHS-pictogram-flamme.svg GHS-pictogram-exclam.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
Danger
H225, H302, H305, H315, H336, H361fd, H373, H411
P201, P202, P210, P233, P235, P240, P241, P242, P243, P260, P264, P271, P273, P280, P281, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P308+P313, P310, P312, P314, P332+P313, P363, P370+P378, P391, P403+P233, P405, P501
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 −26.0 °C (−14.8 °F; 247.2 K)
234.0 °C (453.2 °F; 507.1 K)
Explosive limits 1.2–7.7%
Lethal dose or concentration (LD, LC):
25 g kg−1(oral, rat)
28710 mg/kg (rat, oral) [5]
56137 mg/kg (rat, oral) [5]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 500 ppm (1800 mg/m3) [6]
REL (Recommended)
TWA 50 ppm (180 mg/m3) [6]
IDLH (Immediate danger)
1100 ppm [6]
Related compounds
Related alkanes
Supplementary data page
Hexane (data page)
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 ?)

Hexane ( /ˈhɛkseɪn/ ) or n-hexane is an organic compound, a straight-chain alkane with six carbon atoms and the molecular formula C6H14. [7]

Hexane is a colorless liquid, odorless when pure, and with a boiling point of approximately 69 °C (156 °F). It is widely used as a cheap, relatively safe, largely unreactive, and easily evaporated non-polar solvent, and modern gasoline blends contain about 3% hexane. [8]

The term hexanes refers to a mixture, composed largely (>60%) of n-hexane, with varying amounts of the isomeric compounds 2-methylpentane and 3-methylpentane, and possibly, smaller amounts of nonisomeric C5, C6, and C7 (cyclo)alkanes. These "hexanes" mixtures are cheaper than pure hexane and are often used in large-scale operations not requiring a single isomer (e.g., as cleaning solvent or for chromatography).

Isomers

Common nameIUPAC nameText formulaSkeletal formula
Normal hexane,
n-Hexane		HexaneCH3(CH2)4CH3 Hexane-2D-Skeletal.svg
Isohexane 2-Methylpentane (CH3)2CH(CH2)2CH3 2-metilpentans.svg
3-Methylpentane CH3CH2CH(CH3)CH2CH3 3-metilpentans.svg
2,3-Dimethylbutane (CH3)2CHCH(CH3)2 2,3-dimetilbutans.svg
Neohexane 2,2-Dimethylbutane (CH3)3CCH2CH3 2,2-dimetilbutans.svg

Uses

In industry, hexanes are used in the formulation of glues for shoes, leather products, and roofing. They are also used to extract cooking oils (such as canola oil or soybean oil) from seeds, for cleansing and degreasing a variety of items, and in textile manufacturing.

A typical laboratory use of hexanes is to extract oil and grease contaminants from water and soil for analysis. [9] Since hexane cannot be easily deprotonated, it is used in the laboratory for reactions that involve very strong bases, such as the preparation of organolithiums. For example, butyllithiums are typically supplied as a hexane solution. [10]

Hexanes are commonly used in chromatography as a non-polar solvent. Higher alkanes present as impurities in hexanes have similar retention times as the solvent, meaning that fractions containing hexane will also contain these impurities. In preparative chromatography, concentration of a large volume of hexanes can result in a sample that is appreciably contaminated by alkanes. This may result in a solid compound being obtained as an oil and the alkanes may interfere with analysis.

Production

Hexane is chiefly obtained by refining crude oil. The exact composition of the fraction depends largely on the source of the oil (crude or reformed) and the constraints of the refining. [11] The industrial product (usually around 50% by weight of the straight-chain isomer) is the fraction boiling at 65–70 °C (149–158 °F).

Physical properties

All alkanes are colorless. [12] [13] The boiling points of the various hexanes are somewhat similar and, as for other alkanes, are generally lower for the more branched forms. The melting points are quite different and the trend is not apparent. [14]

Isomer M.P. (°C)M.P. (°F) B.P. (°C)B.P. (°F)
n-hexane−95.3−139.568.7155.7
3-methylpentane−118.0−180.463.3145.9
2-methylpentane (isohexane)−153.7−244.760.3140.5
2,3-dimethylbutane−128.6−199.558.0136.4
2,2-dimethylbutane (neohexane)−99.8−147.649.7121.5

Hexane has considerable vapor pressure at room temperature:

Temperature (°C)Temperature (°F)Vapor pressure (mmHg)Vapor pressure (kPa)
−40−403.360.448
−30−227.120.949
−20−414.011.868
−101425.913.454
03245.376.049
105075.7410.098
2068121.2616.167
2577151.2820.169
3086187.1124.946
40104279.4237.253
50122405.3154.037
60140572.7676.362

Reactivity

Like most alkanes, hexanes characteristically exhibit low reactivity and are suitable solvents for reactive compounds. Commercial samples of n-hexane however often contains methylcyclopentane, which features tertiary C-H bonds, which are incompatible with some radical reactions. [15]

Safety

Inhalation of n-hexane at 5000 ppm for 10 minutes produces marked vertigo; 2500-1000 ppm for 12 hours produces drowsiness, fatigue, loss of appetite, and paresthesia in the distal extremities; 2500–5000 ppm produces muscle weakness, cold pulsation in the extremities, blurred vision, headache, and anorexia. [16] Chronic occupational exposure to elevated levels of n-hexane has been demonstrated to be associated with peripheral neuropathy in auto mechanics in the US, and neurotoxicity in workers in printing presses, and shoe and furniture factories in Asia, Europe, and North America. [17]

The US National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) for hexane isomers (not n-hexane) of 100 ppm (350 mg/m3 (0.15 gr/cu ft)) over an 8-hour workday. [18] However, for n-hexane, the current NIOSH REL is 50 ppm (180 mg/m3 (0.079 gr/cu ft)) over an 8-hour workday. [19] This limit was proposed as a permissible exposure limit (PEL) by the Occupational Safety and Health Administration in 1989; however, this PEL was overruled in US courts in 1992. [20] The current n-hexane PEL in the US is 500 ppm (1,800 mg/m3 (0.79 gr/cu ft)). [19]

Hexane and other volatile hydrocarbons (petroleum ether) present an aspiration risk. [21] n-Hexane is sometimes used as a denaturant for alcohol, and as a cleaning agent in the textile, furniture, and leather industries. It is slowly being replaced with other solvents. [22]

Like gasoline, hexane is highly volatile and is an explosion risk. The 1981 Louisville sewer explosions, which destroyed over 13 mi (21 km) of sewer lines and streets in Kentucky, were caused by ignition of hexane vapors which had been illegally discharged from a soybean processing plant owned by Ralston-Purina. Hexane was attributed as the cause of an explosion that occurred in the National University of Río Cuarto, Argentina on 5 December 2007, due to a hexane spill near a heat-producing machine that exploded, producing a fire that killed one student and injured 24 more.

Incidents

Occupational hexane poisoning has occurred with Japanese sandal workers, Italian shoe workers, [23] Taiwan press proofing workers, and others. [24] Analysis of Taiwanese workers has shown occupational exposure to substances including n-hexane. [25] In 2010–2011, Chinese workers manufacturing iPhones were reported to have suffered hexane poisoning. [26] [27]

Biotransformation

n-Hexane is biotransformed to 2-hexanol and further to 2,5-hexanediol in the body. The conversion is catalyzed by the enzyme cytochrome P450 utilizing oxygen from air. 2,5-Hexanediol may be further oxidized to 2,5-hexanedione, which is neurotoxic and produces a polyneuropathy. [22] In view of this behavior, replacement of n-hexane as a solvent has been discussed. n-Heptane is a possible alternative. [28]

See also

Related Research Articles

<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.

<span class="mw-page-title-main">Octane</span> Hydrocarbon compound with the formula C8H18

Octane is a hydrocarbon and an alkane with the chemical formula C8H18, and the condensed structural formula CH3(CH2)6CH3. Octane has many structural isomers that differ by the location of branching in the carbon chain. One of these isomers, 2,2,4-trimethylpentane (commonly called iso-octane), is used as one of the standard values in the octane rating scale.

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

Heptane or n-heptane is the straight-chain alkane with the chemical formula H3C(CH2)5CH3 or C7H16. When used as a test fuel component in anti-knock test engines, a 100% heptane fuel is the zero point of the octane rating scale (the 100 point is 100% iso-octane). Octane number equates to the anti-knock qualities of a comparison mixture of heptane and iso-octane which is expressed as the percentage of iso-octane in heptane, and is listed on pumps for gasoline (petrol) dispensed globally.

<span class="mw-page-title-main">Pentane</span> Alkane with 5 carbon atoms

Pentane is an organic compound with the formula C5H12—that is, an alkane with five carbon atoms. The term may refer to any of three structural isomers, or to a mixture of them: in the IUPAC nomenclature, however, pentane means exclusively the n-pentane isomer, in which case pentanes refers to a mixture of them; the other two are called isopentane (methylbutane) and neopentane (dimethylpropane). Cyclopentane is not an isomer of pentane because it has only 10 hydrogen atoms where pentane has 12.

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

Nonane is a linear alkane hydrocarbon with the chemical formula C9H20. It is a colorless, flammable liquid, occurring primarily in the component of the petroleum distillate fraction commonly called kerosene, which is used as a heating, tractor, and jet fuel. Nonane is also used as a solvent, distillation chaser, fuel additive, and a component in biodegradable detergents.

<span class="mw-page-title-main">White spirit</span> Petroleum-derived clear, transparent liquid

White spirit (AU, UK and Ireland) or mineral spirits (US, Canada), also known as mineral turpentine (AU/NZ/ZA), turpentine substitute, and petroleum spirits, is a petroleum-derived clear liquid used as a common organic solvent in painting. There are also terms for specific kinds of white spirit, including Stoddard solvent and solvent naphtha (petroleum). White spirit is often used as a paint thinner, or as a component thereof, though paint thinner is a broader category of solvent. Odorless mineral spirits (OMS) have been refined to remove the more toxic aromatic compounds, and are recommended for applications such as oil painting.

The permissible exposure limit is a legal limit in the United States for exposure of an employee to a chemical substance or physical agent such as high level noise. Permissible exposure limits were established by the Occupational Safety and Health Administration (OSHA). Most of OSHA's PELs were issued shortly after adoption of the Occupational Safety and Health (OSH) Act in 1970.

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

Amyl acetate (pentyl acetate) is an organic compound and an ester with the chemical formula CH3COO[CH2]4CH3 and the molecular weight 130.19 g/mol. It is colorless and has a scent similar to bananas and apples. The compound is the condensation product of acetic acid and 1-pentanol. However, esters formed from other pentanol isomers (amyl alcohols), or mixtures of pentanols, are often referred to as amyl acetate. The symptoms of exposure to amyl acetate in humans are dermatitis, central nervous system depression, narcosis and irritation to the eyes and nose.

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

Hydrogen selenide is an inorganic compound with the formula H2Se. This hydrogen chalcogenide is the simplest and most commonly encountered hydride of selenium. H2Se is a colorless, flammable gas under standard conditions. It is the most toxic selenium compound with an exposure limit of 0.05 ppm over an 8-hour period. Even at extremely low concentrations, this compound has a very irritating smell resembling that of decayed horseradish or "leaking gas", but smells of rotten eggs at higher concentrations.

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

Isopropyl acetate is an ester, an organic compound which is the product of esterification of acetic acid and isopropanol. It is a clear, colorless liquid with a characteristic fruity odor.

<span class="mw-page-title-main">2,2-Dimethylbutane</span> Chemical compound

2,2-Dimethylbutane, trivially known as neohexane, is an organic compound with formula C6H14 or (H3C-)3-C-CH2-CH3. It is therefore an alkane, indeed the most compact and branched of the hexane isomers — the only one with a quaternary carbon and a butane (C4) backbone.

1,1,2-Trichloroethane, vinyl trichloride or 1,1,2-TCA, is an organochloride solvent with the molecular formula C2H3Cl3 and the structural formula CH2Cl—CHCl2. It is a colourless, sweet-smelling liquid that does not dissolve in water, but is soluble in most organic solvents. It is an isomer of 1,1,1-trichloroethane, and a byproduct of its manufacture.

<span class="mw-page-title-main">1,2-Dichlorobenzene</span> Chemical compound

1,2-Dichlorobenzene, or orthodichlorobenzene (ODCB), is an aryl chloride and isomer of dichlorobenzene with the formula C6H4Cl2. This colourless liquid is poorly soluble in water but miscible with most organic solvents. It is a derivative of benzene, consisting of two adjacent chlorine atoms.

<span class="mw-page-title-main">Occupational hazard</span> Hazard experienced in the workplace

An occupational hazard is a hazard experienced in the workplace. This encompasses many types of hazards, including chemical hazards, biological hazards (biohazards), psychosocial hazards, and physical hazards. In the United States, the National Institute for Occupational Safety and Health (NIOSH) conduct workplace investigations and research addressing workplace health and safety hazards resulting in guidelines. The Occupational Safety and Health Administration (OSHA) establishes enforceable standards to prevent workplace injuries and illnesses. In the EU, a similar role is taken by EU-OSHA.

Xylidine can refer to any of the six isomers of xylene amine, or any mixture of them.

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3-Methylpentane is a branched alkane with the molecular formula C6H14. It is a structural isomer of hexane composed of a methyl group bonded to the third carbon atom in a pentane chain. It is of similar structure to the isomeric 2-methylpentane, which has the methyl group located on the second carbon of the pentane chain.

Petroleum naphtha is an intermediate hydrocarbon liquid stream derived from the refining of crude oil with CAS-no 64742-48-9. It is most usually desulfurized and then catalytically reformed, which rearranges or restructures the hydrocarbon molecules in the naphtha as well as breaking some of the molecules into smaller molecules to produce a high-octane component of gasoline.

<span class="mw-page-title-main">EPN (insecticide)</span> Chemical compound

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References

  1. ↑ "n-hexane – Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records. Archived from the original on 8 March 2012. Retrieved 31 December 2011.
  2. ↑ Hofmann, August Wilhelm Von (1 January 1867). "I. On the action of trichloride of phosphorus on the salts of the aromatic monamines". Proceedings of the Royal Society of London. 15: 54–62. doi:10.1098/rspl.1866.0018. S2CID   98496840.
  3. ↑ William M. Haynes (2016). CRC Handbook of Chemistry and Physics (97th ed.). Boca Raton: CRC Press. pp. 3–298. ISBN   978-1-4987-5429-3.
  4. ↑ GHS Classification on [PubChem]
  5. 1 2 "n-Hexane". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  6. 1 2 3 NIOSH Pocket Guide to Chemical Hazards. "#0322". National Institute for Occupational Safety and Health (NIOSH).
  7. ↑ PubChem. "n-HEXANE". pubchem.ncbi.nlm.nih.gov. Retrieved 3 November 2023.
  8. ↑ "n-Hexane - Hazardous Agents". Haz-Map. Retrieved 7 July 2022.
  9. ↑ Use of ozone depleting substances in laboratories. Kbh: Nordisk Ministerråd. 2003. ISBN   92-893-0884-2. OCLC   474188215. Archived from the original on 16 July 2012.
  10. ↑ Schwindeman, James A.; Woltermann, Chris J.; Letchford, Robert J. (1 May 2002). "Safe handling of organolithium compounds in the laboratory". Chemical Health & Safety. 9 (3): 6–11. doi:10.1016/s1074-9098(02)00295-2. ISSN   1074-9098.
  11. ↑ Le Van Mao, R.; Melancon, S.; Gauthier-Campbell, C.; Kletnieks, P. (1 May 2001). "Selective deep catalytic cracking process (SDCC) of petroleum feedstocks for the production of light olefins. I. The Catlever effect obtained with a two reaction-zones system on the conversion of n-hexane". Catalysis Letters. 73 (2): 181–186. doi:10.1023/A:1016685523095. ISSN   1572-879X. S2CID   98167823.
  12. ↑ "Organic Chemistry-I" (PDF). Nsdl.niscair.res.in. Archived from the original (PDF) on 29 October 2013. Retrieved 17 February 2014.
  13. ↑ "13. Hydrocarbons | Textbooks". Textbook.s-anand.net. Archived from the original on 6 October 2014. Retrieved 17 February 2014.
  14. ↑ William D. McCain (1990). The properties of petroleum fluids. PennWell. ISBN   978-0-87814-335-1.
  15. ↑ Koch, H.; Haaf, W. (1973). "1-Adamantanecarboxylic Acid". Organic Syntheses ; Collected Volumes, vol. 5, p. 20.
  16. ↑ "N-HEXANE". Toxicology data network Hazardous Substances Data Bank. National Library of Medicine. Archived from the original on 4 September 2015.
  17. ↑ Centers for Disease Control and Prevention (CDC) (16 November 2001). "n-Hexane-related peripheral neuropathy among automotive technicians--California, 1999-2000". MMWR. Morbidity and Mortality Weekly Report. 50 (45): 1011–1013. ISSN   0149-2195. PMID   11724159.
  18. ↑ "CDC – NIOSH Pocket Guide to Chemical Hazards – Hexane isomers (excluding n-Hexane)". cdc.gov. Archived from the original on 31 October 2015. Retrieved 3 November 2015.
  19. 1 2 CDC (28 March 2018). "n-Hexane". Centers for Disease Control and Prevention. Retrieved 3 May 2020.
  20. ↑ "Appendix G: 1989 Air Contaminants Update Project - Exposure Limits NOT in Effect". www.cdc.gov. 20 February 2020. Retrieved 3 May 2020.
  21. ↑ Gad, Shayne C (2005), "Petroleum Hydrocarbons", Encyclopedia of Toxicology, vol. 3 (2nd ed.), Elsevier, pp. 377–379
  22. 1 2 Clough, Stephen R; Mulholland, Leyna (2005). "Hexane". Encyclopedia of Toxicology. Vol. 2 (2nd ed.). Elsevier. pp. 522–525.
  23. ↑ Rizzuto, N; De Grandis, D; Di Trapani, G; Pasinato, E (1980). "N-hexane polyneuropathy. An occupational disease of shoemakers". European Neurology. 19 (5): 308–15. doi:10.1159/000115166. PMID   6249607.
  24. ↑ n-Hexane, Environmental Health Criteria, World Health Organization, 1991, archived from the original on 19 March 2014
  25. ↑ Liu, C. H.; Huang, C. Y.; Huang, C. C. (2012). "Occupational Neurotoxic Diseases in Taiwan". Safety and Health at Work. 3 (4): 257–67. doi:10.5491/SHAW.2012.3.4.257. PMC   3521924 . PMID   23251841.
  26. ↑ "Workers poisoned while making iPhones – ABC News (Australian Broadcasting Corporation)". Australian Broadcasting Corporation. 26 October 2010. Archived from the original on 8 April 2011. Retrieved 17 March 2015.
  27. ↑ David Barboza (22 February 2011). "Workers Sickened at Apple Supplier in China". The New York Times. Archived from the original on 7 April 2015. Retrieved 17 March 2015.
  28. ↑ Filser JG, Csanády GA, Dietz W, Kessler W, Kreuzer PE, Richter M, Störmer A (1996). "Comparative Estimation of the Neurotoxic Risks of N-Hexane and N-Heptane in Rats and Humans Based on the Formation of the Metabolites 2,5-Hexanedione and 2,5-Heptanedione". Biological Reactive Intermediates V. Advances in Experimental Medicine and Biology. Vol. 387. pp. 411–427. doi:10.1007/978-1-4757-9480-9_50. ISBN   978-1-4757-9482-3. PMID   8794236.
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