Pentane
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Names | |||
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Preferred IUPAC name
Pentane[2] | |||
Other names
Quintane;[1] Refrigerant-4-13-0
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Identifiers | |||
3D model (
JSmol ) |
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969132 | |||
ChEBI | |||
ChEMBL | |||
ChemSpider | |||
DrugBank | |||
ECHA InfoCard
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100.003.358 | ||
EC Number |
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1766 | |||
MeSH | pentane | ||
PubChem CID
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RTECS number
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UNII | |||
UN number | 1265 | ||
CompTox Dashboard (EPA)
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Properties[4] | |||
C5H12 | |||
Molar mass | 72.151 g·mol−1 | ||
Appearance | Colourless liquid | ||
Odor | Gasoline-like[3] | ||
Density | 0.626 g/mL; 0.6262 g/mL (20 °C) | ||
Melting point | −130.5 to −129.1 °C; −202.8 to −200.3 °F; 142.7 to 144.1 K | ||
Boiling point | 35.9 to 36.3 °C; 96.5 to 97.3 °F; 309.0 to 309.4 K | ||
40 mg/L (20 °C) | |||
log P | 3.255 | ||
Vapor pressure | 57.90 kPa (20.0 °C) | ||
Henry's law
constant (kH) |
7.8 nmol Pa−1 kg−1 | ||
Acidity (pKa) | ~45 | ||
Basicity (pKb) | ~59 | ||
UV-vis (λmax) | 200 nm | ||
-63.05·10−6 cm3/mol | |||
Refractive index (nD)
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1.358 | ||
Viscosity | 0.240 mPa·s (at 20 °C) | ||
Thermochemistry | |||
Heat capacity (C)
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167.19 J K−1 mol−1 | ||
Std molar
entropy (S⦵298) |
263.47 J K−1 mol−1 | ||
Std enthalpy of (ΔfH⦵298)formation |
−174.1–−172.9 kJ mol−1 | ||
Std enthalpy of (ΔcH⦵298)combustion |
−3.5095–−3.5085 MJ mol−1 | ||
Hazards | |||
GHS labelling: | |||
Danger | |||
H225, H304, H336, H411 | |||
P210, P261, P273, P301+P310, P331 | |||
NFPA 704 (fire diamond) | |||
Flash point | −49.0 °C (−56.2 °F; 224.2 K) | ||
260.0 °C (500.0 °F; 533.1 K) | |||
Explosive limits
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1.5–7.8%[3] | ||
Lethal dose or concentration (LD, LC): | |||
LD50 (median dose)
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LC50 (median concentration)
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130,000 mg/m3 (mouse, 30 min) 128,200 ppm (mouse, 37 min) 325,000 mg/m3 (mouse, 2 hr)[5] | ||
NIOSH (US health exposure limits): | |||
PEL (Permissible)
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TWA 1000 ppm (2950 mg/m3)[3] | ||
REL (Recommended)
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TWA 120 ppm (350 mg/m3) C 610 ppm (1800 mg/m3) [15-minute][3] | ||
IDLH (Immediate danger) |
1500 ppm[3] | ||
Related compounds | |||
Related alkanes
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Supplementary data page | |||
Pentane (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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Pentane is an
Pentanes are components of some fuels and are employed as specialty solvents in the laboratory. Their properties are very similar to those of butanes and hexanes.
Isomers
Common name | normal pentane unbranched pentane n-pentane |
isopentane | neopentane |
IUPAC name | pentane | 2-methylbutane | 2,2-dimethylpropane |
Molecular diagram | |||
Skeletal diagram
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Melting point (°C)[6] | −129.8 | −159.9 | −16.6 |
Boiling point (°C)[6] | 36.0 | 27.7 | 9.5 |
Density (0 °C,kg/m3)[6] |
621 | 616 | 586 |
Industrial uses
Pentanes are some of the primary
Acid-catalyzed isomerization gives isopentane, which is used in producing high-octane fuels.[7]
Because of their low boiling points, low cost, and relative safety, pentanes are used as a working medium in geothermal power stations and organic Rankine cycles. It is also used in some blended refrigerants.
Pentanes are solvents in many ordinary products, e.g. in some pesticides.[8]
Laboratory use
Pentanes are relatively inexpensive and are the most
They are often used in liquid chromatography.
Physical properties
The boiling points of the pentane isomers range from about 9 to 36 °C. As is the case for other alkanes, the more thickly branched isomers tend to have lower boiling points.
The same tends to be true for the melting points of alkane isomers, and that of isopentane is 30 °C lower than that of n-pentane. However, the melting point of neopentane, the most heavily branched of the three, is 100 °C higher than that of isopentane. The anomalously high melting point of neopentane has been attributed to the tetrahedral molecules packing more closely in solid form; this explanation is contradicted by the fact that neopentane has a lower density than the other two isomers,[9] and the high melting point is actually caused by neopentane's significantly lower entropy of fusion.
The branched
Rotation about two central single C-C bonds of n-pentane produces four different conformations.[12]
Reactions
Like other
- C5H12 + 8 O2 → 5 CO2 + 6 H2O + heat/energy
Like other
- C5H12 + Cl2 → C5H11Cl + HCl
Such reactions are unselective; with n-pentane, the result is a mixture of the 1-, 2-, and 3-chloropentanes, as well as more highly chlorinated derivatives. Other radical halogenations can also occur.
Production and occurrence
Pentane is produced by
It occurs in alcoholic beverages and in hop oil.[13] It is a component of exhaled breath for some individuals. A degradation product of unsaturated fatty acids, its presence is associated with some diseases and cancers.[14]
References
- S2CID 98496840.
- ISBN 978-0-85404-182-4.
- ^ a b c d e NIOSH Pocket Guide to Chemical Hazards. "#0486". National Institute for Occupational Safety and Health (NIOSH).
- ^ Record of n-Pentane in the GESTIS Substance Database of the Institute for Occupational Safety and Health, accessed on 19 April 2011.
- ^ "n-Pentane". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
- ^
- ISBN 978-3-527-30673-2.
- ISBN 978-0-471-73518-2.
- ISSN 0888-5885.
- Standard enthalpy change of formation (data table).
- ISSN 0021-9614.
- PMID 19152252.
- ^ a b "Pentane". PubChem. Retrieved 2023-06-29.
- PMID 10410929.
External links
- International Chemical Safety Card 0534 at ILO.org
- NIOSH Pocket Guide to Chemical Hazards at CDC.gov
- Phytochemical data for pentane at Ars-grin.gov