Hexane
Names | |
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Preferred IUPAC name
Hexane[2] | |
Other names
Sextane,[1] hexacarbane
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Identifiers | |
3D model (
JSmol ) |
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1730733 | |
ChEBI | |
ChEMBL | |
ChemSpider | |
DrugBank | |
ECHA InfoCard
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100.003.435 |
EC Number |
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1985 | |
KEGG | |
MeSH | n-hexane |
PubChem CID
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RTECS number
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UNII | |
UN number | 1208 |
CompTox Dashboard (EPA)
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Properties | |
C6H14 | |
Molar mass | 86.178 g·mol−1 |
Appearance | Colorless 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) |
Henry's law
constant (kH) |
7.6 nmol Pa−1 kg−1 |
UV-vis (λmax) | 200 nm |
−74.6·10−6 cm3/mol | |
Refractive index (nD)
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1.375 |
Viscosity | 0.3 mPa·s |
0.08 D | |
Thermochemistry | |
Heat capacity (C)
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265.2 J K−1 mol−1 |
Std molar
entropy (S⦵298) |
296.06 J K−1 mol−1 |
Std enthalpy of (ΔfH⦵298)formation |
−199.4–−198.0 kJ mol−1 |
Std enthalpy of (ΔcH⦵298)combustion |
−4180–−4140 kJ mol−1 |
Hazards | |
Occupational safety and health (OHS/OSH): | |
Main hazards
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pulmonary oedema, pneumonitis[4]
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GHS labelling: | |
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) | |
Flash point | −26.0 °C (−14.8 °F; 247.2 K) |
234.0 °C (453.2 °F; 507.1 K) | |
Explosive limits
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1.2–7.7% |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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25 g kg−1 (oral, rat) 28710 mg/kg (rat, oral)[6] |
LDLo (lowest published)
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56137 mg/kg (rat, oral)[6] |
NIOSH (US health exposure limits): | |
PEL (Permissible)
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TWA 500 ppm (1800 mg/m3)[5] |
REL (Recommended)
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TWA 50 ppm (180 mg/m3)[5] |
IDLH (Immediate danger) |
1100 ppm[5] |
Related compounds | |
Related alkanes
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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).
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Hexane (
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
The term hexanes refers to a
Isomers
Common name | IUPAC name | Text formula | Skeletal formula |
---|---|---|---|
Normal hexane, n-Hexane |
Hexane | CH3(CH2)4CH3 | |
Isohexane | 2-Methylpentane | (CH3)2CH(CH2)2CH3 | |
3-Methylpentane | CH3CH2CH(CH3)CH2CH3 | ||
2,3-Dimethylbutane | (CH3)2CHCH(CH3)2 | ||
Neohexane | 2,2-Dimethylbutane | (CH3)3CCH2CH3 |
Uses
In industry, hexanes are used in the formulation of
A typical laboratory use of hexanes is to extract oil and grease contaminants from water and soil for analysis.[11] 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.[12]
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.[13] 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.[14][15] 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.[16]
Isomer | M.P. (°C) | M.P. (°F) | B.P. (°C) | B.P. (°F) |
---|---|---|---|---|
n-hexane | −95.3 | −139.5 | 68.7 | 155.7 |
3-methylpentane | −118.0 | −180.4 | 63.3 | 145.9 |
2-methylpentane (isohexane) | −153.7 | −244.7 | 60.3 | 140.5 |
2,3-dimethylbutane | −128.6 | −199.5 | 58.0 | 136.4 |
2,2-dimethylbutane (neohexane) | −99.8 | −147.6 | 49.7 | 121.5 |
Hexane has considerable vapor pressure at room temperature:
Temperature (°C) | Temperature (°F) | Vapor pressure ( mmHg )
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Vapor pressure ( kPa )
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---|---|---|---|
−40 | −40 | 3.36 | 0.448 |
−30 | −22 | 7.12 | 0.949 |
−20 | −4 | 14.01 | 1.868 |
−10 | 14 | 25.91 | 3.454 |
0 | 32 | 45.37 | 6.049 |
10 | 50 | 75.74 | 10.098 |
20 | 68 | 121.26 | 16.167 |
25 | 77 | 151.28 | 20.169 |
30 | 86 | 187.11 | 24.946 |
40 | 104 | 279.42 | 37.253 |
50 | 122 | 405.31 | 54.037 |
60 | 140 | 572.76 | 76.362 |
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.[17]
Safety
Inhalation of n-hexane at 5000 ppm for 10 minutes produces marked vertigo; 2500-1000 ppm for 12 hours produces
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.[20] However, for n-hexane, the current NIOSH REL is 50 ppm (180 mg/m3 (0.079 gr/cu ft)) over an 8-hour workday.[21] 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.[22] The current n-hexane PEL in the US is 500 ppm (1,800 mg/m3 (0.79 gr/cu ft)).[21]
Hexane and other volatile hydrocarbons (petroleum ether) present an aspiration risk.[23] 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.[24]
Like gasoline, hexane is highly volatile and is an explosion risk. The 1981
Incidents
Occupational hexane poisoning has occurred with Japanese sandal workers, Italian shoe workers,[25] Taiwan press proofing workers, and others.[26] Analysis of Taiwanese workers has shown occupational exposure to substances including n-hexane.[27] In 2010–2011, Chinese workers manufacturing iPhones were reported to have suffered hexane poisoning.[28][29]
Biotransformation
n-Hexane is biotransformed to
See also
References
- S2CID 98496840.
- ^ "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.
- ISBN 978-1-4987-5429-3.
- ^ GHS Classification on [PubChem]
- ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0322". National Institute for Occupational Safety and Health (NIOSH).
- ^ a b "n-Hexane". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
- ^ PubChem. "n-HEXANE". pubchem.ncbi.nlm.nih.gov. Retrieved 3 November 2023.
- ^ "n-Hexane - Hazardous Agents". Haz-Map. Retrieved 7 July 2022.
- ^ "The Tofurky Company : Our Ingredients". Tofurky.com. Archived from the original on 17 March 2015. Retrieved 17 March 2015.
- ^ Palmer, Brian (26 April 2010). "A study found hexane in soy protein. Should you stop eating veggie burgers?". Slate.com. Archived from the original on 9 March 2015. Retrieved 17 March 2015.
- OCLC 474188215. Archived from the originalon 16 July 2012.
- ISSN 1074-9098.
- S2CID 98167823.
- ^ "Organic Chemistry-I" (PDF). Nsdl.niscair.res.in. Archived from the original (PDF) on 29 October 2013. Retrieved 17 February 2014.
- ^ "13. Hydrocarbons | Textbooks". Textbook.s-anand.net. Archived from the original on 6 October 2014. Retrieved 17 February 2014.
- ISBN 978-0-87814-335-1.
- ^ Koch, H.; Haaf, W. (1973). "1-Adamantanecarboxylic Acid". Organic Syntheses; Collected Volumes, vol. 5, p. 20.
- National Library of Medicine. Archivedfrom the original on 4 September 2015.
- PMID 11724159.
- ^ "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.
- ^ a b CDC (28 March 2018). "n-Hexane". Centers for Disease Control and Prevention. Retrieved 3 May 2020.
- ^ "Appendix G: 1989 Air Contaminants Update Project - Exposure Limits NOT in Effect". www.cdc.gov. 20 February 2020. Retrieved 3 May 2020.
- ^ Gad, Shayne C (2005), "Petroleum Hydrocarbons", Encyclopedia of Toxicology, vol. 3 (2nd ed.), Elsevier, pp. 377–379
- ^ a b Clough, Stephen R; Mulholland, Leyna (2005). "Hexane". Encyclopedia of Toxicology. Vol. 2 (2nd ed.). Elsevier. pp. 522–525.
- PMID 6249607.
- Environmental Health Criteria, World Health Organization, 1991, archivedfrom the original on 19 March 2014
- PMID 23251841.
- ^ "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.
- ^ 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.
- PMID 8794236.
External links
- International Chemical Safety Card 1262 (2-methylpentane)
- Material Safety Data Sheet for Hexane
- National Pollutant Inventory – n-hexane fact sheet
- Phytochemica l database entry
- Center for Disease Control and Prevention
- Warning from National Safety Council "COMMON CHEMICAL AFFECTS AUTO MECHANICS"
- Australian National Pollutant Inventory (NPI) page
- "EPA does not consider n-hexane classifiable as a human carcinogen." Federal Register / Vol. 66, No. 71 / Thursday, 12 April 2001 / Rules and Regulations