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Hexane
Hexane
/ˈhɛkseɪn/ is an alkane of six carbon atoms, with the chemical formula C6H14. The term may refer to any of the five structural isomers with that formula, or to a mixture of them.[5] In IUPAC nomenclature, however, hexane is the unbranched isomer (n-hexane); the other four isomers are named as methylated derivatives of pentane and butane. IUPAC also uses the term as the root of many compounds with a linear six-carbon backbone, such as 2-methylhexane. Hexanes are significant constituents of gasoline. They are all colorless liquids, odorless when pure, with boiling points between 50 and 70 °C (122 and 158 °F). They are widely used as cheap, relatively safe, largely unreactive, and easily evaporated non-polar solvents.

Contents

1 Isomers 2 Uses 3 Production 4 Physical properties 5 Reactivity 6 Safety

6.1 Incidents 6.2 Biotransformation

7 See also 8 References 9 External links

Isomers[edit]

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[edit] 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 soy oil) from seeds, for cleansing and degreasing a variety of items, and in textile manufacturing. They are commonly used in food based soybean oil extraction in the United States, and are potentially present as contaminants in all soy food products in which the technique is used; the lack of regulation by the FDA
FDA
of this contaminant is a matter of some controversy.[6][7] A typical laboratory use of hexanes is to extract oil and grease contaminants from water and soil for analysis.[8] 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.[citation needed] 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.[citation needed] Production[edit] Hexanes are 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. 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[edit] All alkanes are colorless.[9][10] 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.[11]

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
Hexane
has considerable vapor pressure at room temperature:

Temperature (°C) Temperature (°F) Vapor pressure
Vapor pressure
(mmHg) Vapor pressure
Vapor pressure
(kPa)

−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[edit] Like most alkanes, hexane characteristically exhibits 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.[12] Safety[edit] The acute toxicity of n-hexane is rather low, requiring grams per kilogram. 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.[13] The 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.[14] Hexane
Hexane
and other volatile hydrocarbons (petroleum ether) present an aspiration risk.[15] n- Hexane
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.[16] Incidents[edit] Occupational hexane poisoning has occurred with Japanese sandal workers, Italian shoe workers,[17] Taiwan
Taiwan
press proofing workers, and others.[18] Analysis of Taiwanese workers has shown occupational exposure to substances including n-hexane.[19] In 2010–2011, Chinese workers manufacturing iPhones were reported to have suffered hexane poisoning.[20][21] Biotransformation[edit] n- Hexane
Hexane
is biotransformed to 2-hexanol
2-hexanol
and further to 2,5-hexanediol in the body. The conversion is catalyzed by the enzyme cytochrome P450 utilizing oxygen from air. The pathway is called omega oxidation. 2,5-Hexanediol may be further oxidized to 2,5-hexanedione, which is neurotoxic and produces a polyneuropathy.[16] In view of this behavior, replacement of n-hexane as a solvent has been discussed. n- Heptane
Heptane
is a possible alternative.[22] See also[edit]

Cyclohexane

References[edit]

^ http://rspl.royalsocietypublishing.org/content/15/54.full.pdf+html ^ "n-hexane – Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records. Retrieved 31 December 2011.  ^ 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 and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).  ^ "C5 and C6 alkanes". A and B Scott Organic Chemistry. Retrieved 30 October 2007.  ^ "The Tofurky Company : Our Ingredients". Tofurky.com. Retrieved 2015-03-17.  ^ Palmer, Brian (2010-04-26). "A study found hexane in soy protein. Should you stop eating veggie burgers?". Slate.com. Retrieved 2015-03-17.  ^ Use of ozone depleting substances in laboratories. The Nordic Council (2003). ISBN 92-893-0884-2 ^ "Organic Chemistry-I" (PDF). Nsdl.niscair.res.in. Retrieved 2014-02-17.  ^ "13. Hydrocarbons Textbooks". Textbook.s-anand.net. Archived from the original on 6 October 2014. Retrieved 17 February 2014.  ^ William D. McCain (1990). The properties of petroleum fluids. PennWell. ISBN 0-87814-335-1.  ^ Koch, H.; Haaf, W. (1973). "1-Adamantanecarboxylic Acid". Organic Syntheses. ; Collective Volume, 5, p. 20  ^ "N-HEXANE". Toxicology data network Hazardous Substances Data Bank. National Library of Medicine.  ^ "CDC – NIOSH Pocket Guide to Chemical Hazards – Hexane
Hexane
isomers (excluding n-Hexane)". www.cdc.gov. Retrieved 2015-11-03.  ^ Gad, Shayne C (2005), " Petroleum
Petroleum
Hydrocarbons", Encyclopedia of Toxicology, 3 (2nd ed.), Elsevier, pp. 377–379  ^ a b Clough, Stephen R; Mulholland, Leyna (2005). "Hexane". Encyclopedia of Toxicology. 2 (2nd ed.). Elsevier. pp. 522–525.  ^ 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. PMID 6249607.  ^ n-Hexane, Environmental Health Criteria (122), World Health Organization, 1991  ^ 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.  ^ "Workers poisoned while making iPhones – ABC News (Australian Broadcasting Corporation)". Abc.net.au. 2010-10-26. Retrieved 2015-03-17.  ^ David Barboza (February 22, 2011). "Workers Sickened at Apple Supplier in China". The New York Times. Retrieved 2015-03-17.  ^ 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". Adv Exp Med Biol. 387: 411–427. PMID 8794236. 

External links[edit]

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

v t e

Alkanes

Methane
Methane
(CH 4) Ethane (C 2H 6) Propane
Propane
(C 3H 8) Butane
Butane
(C 4H 10) Pentane
Pentane
(C 5H 12) Hexane
Hexane
(C 6H 14) Heptane
Heptane
(C 7H 16) Octane
Octane
(C 8H 18) Nonane
Nonane
(C 9H 20) Decane
Decane
(C 10H 22) Undecane
Undecane
(C 11H 24) Dodecane
Dodecane
(C 12H 26) Tridecane
Tridecane
(C 13H 28) Tetradecane
Tetradecane
(C 14H 30) Pentadecane
Pentadecane
(C 15H 32) Hexadecane
Hexadecane
/ Cetane (C 16H 34) Heptadecane
Heptadecane
(C 17H 36) Octadecane
Octadecane
(C 18H 38) Nonadecane
Nonadecane
(C 19H 40) Icosane
Icosane
(C 20H 42) Heneicosane
Heneicosane
(C 21H 44) Tetracosane
Tetracosane
(C 24H 50) Nonacosane
Nonacosane
(C 29H 60) Hentriacontane
Hentriacontane
(C 31H 64)

Higher alkanes List of alkanes

v t e

Binary compounds of hydrogen

Alkali metal hydrides

LiH NaH KH RbH CsH

Lithium hydride, LiH ionic metal hydride

Beryllium hydride Left (gas phase): BeH2 covalent metal hydride Right: (BeH2)n (solid phase) polymeric metal hydride

Borane
Borane
and diborane Left: BH3 (special conditions), covalent metalloid hydride Right: B2H6 (standard conditions), dimeric metalloid hydride

Methane, CH4 covalent nonmetal hydride

Ammonia, NH3 covalent nonmetal hydride

Water, H2O covalent nonmetal hydride

Hydrogen fluoride, HF covalent nonmetal hydride

Alkaline earth hydrides

Monohydrides

BeH MgH CaH SrH BaH

BeH2 MgH2 CaH2 SrH2 BaH2

Group 13 hydrides

Boranes

BH3 B2H6 B2H2 B2H4

Alanes

AlH3 Al2H6

Gallanes

GaH3 Ga2H6

Indiganes

InH3 In2H6

Thallanes

TlH3 Tl2H6

B2H2 B2H4 B4H10 B5H9 B5H11 B6H10 B6H12 B10H14 B18H22

Group 14 hydrides

Linear alkanes

CH4 C2H6 C3H8 C4H10 C5H12 C6H14 C7H16 C8H18 C9H20 C10H22 more...

Linear alkenes

C2H4 C3H6 C4H8 C5H10 C6H12 C7H14 C8H16 C9H18 C10H20 more...

Linear alkynes

C2H2 C3H4 C4H6 C5H8 C6H10 C7H12 C8H14 C9H16 C10H18 more...

Silanes

SiH4 Si2H6 Si3H8 Si4H10 Si5H12 Si6H14 Si7H16 Si8H18 Si9H20 Si10H22 more...

Silenes

Si2H4

Silynes

Si2H2

Germanes

GeH4 Ge2H6 Ge3H8 Ge4H10 Ge5H12

Stannanes

SnH4 Sn2H6

Plumbanes

PbH4

CH CH2 CH3 C2H Cycloalkanes Cycloalkenes Annulenes Many more

Pnictogen hydrides

Azanes

NH3 N2H4 N3H5 N4H6 N5H7 N6H8 N7H9 N8H10 N9H11 N10H12 more...

Azenes

N2H2 N3H3 N4H4

Phosphanes

PH3 P2H4 P3H5 P4H6 P5H7 P6H8 P7H9 P8H10 P9H11 P10H12 more...

Phosphenes

P2H2 P3H3 P4H4

Arsanes

AsH3 As2H4

Stibanes

SbH3

Bismuthanes

BiH3

HN3 NH

radical

Hydrogen chalcogenides

Polyoxidanes

H2O H2O2 H2O3 H2O4 H2O5 H2O6 H2O7 H2O8 H2O9 H2O10 more...

Polysulfanes

H2S H2S2 H2S3 H2S4 H2S5 H2S6 H2S7 H2S8 H2S9 H2S10 more...

Selanes

H2Se H2Se2

Tellanes

H2Te H2Te2

Polanes

PoH2

HO HO2 HO3 H2O+–O– H2S=S (HS)2S+–S– HS HDO D2O T2O

Hydrogen halides

HF HCl HBr HI HAt

Transition metal hydrides

ScH2 YH2 YH3 TiH2 ZrH2 HfH2 VH VH2 NbH NbH2 TaH CrH CrH2 CrHx NiH PdHx (x < 1) FeH FeH2 FeH5 CuH ZnH2 CdH2 HgH2

Lanthanide hydrides

LaH2 LaH3 CeH2 CeH3 PrH2 PrH3 NdH2 NdH3 SmH2 SmH3 EuH2 GdH2 GdH3 TbH2 TbH3 DyH2 DyH3 HoH2 HoH3 ErH2 ErH3 TmH2 TmH3 YbH2 YbH2.5 LuH2 LuH3

Actinide hydrides

AcH2 ThH2 Th4H15 PaH3 UH3 NpH2 NpH3 PuH2 PuH3 Am

.