Difference between revisions of "Pentane"

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(Created page with "PTFE seal tape. '''Polytetrafluoroethylene''' or '''PTFE''' or '''Teflon''' is a synthetic fluoropolymer of tetrafluoroethylene,...")
 
 
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[[File:PTFE_thread_seal_tape.jpg|thumb|300px|PTFE seal tape.]]
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{{Chembox
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'''Polytetrafluoroethylene''' or '''PTFE''' or '''Teflon''' is a synthetic fluoropolymer of tetrafluoroethylene, well known for its chemical inertness and very low coefficient of friction.
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| Name = Pentane
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| Reference =
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| IUPACName = Pentane
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| PIN = n-Pentane
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| SystematicName = n-Pentane
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| OtherNames = Amyl hydride<br>Pentan<br>Skellysolve A
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| ImageFile = Pentane_sample.jpg
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| ImageSize = 250
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| ImageCaption = Distilled lab-grade pentane.
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<!-- Sections -->
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| Section1 = {{Chembox Identifiers
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| 3DMet =
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| Abbreviations =
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| SMILES = CCCCC
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  }}
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| Section2 = {{Chembox Properties
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| AtmosphericOHRateConstant =
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| Appearance = Colorless volatile liquid
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| BoilingPt =
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| BoilingPtC = 36
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| BoilingPt_ref =
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| BoilingPt_notes =
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| Density = 0.626 g/cm<sup>3</sup>
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| Formula = C<sub>5</sub>H<sub>12</sub>
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| HenryConstant =
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| LogP = 3.255
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| MolarMass = 72.15 g/mol
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| MeltingPt =
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| MeltingPtC = −129.8
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| MeltingPt_ref =
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| MeltingPt_notes = (decomposes)
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| Odor = Lighter-fluid like
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| pKa = ~45
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| pKb = ~59
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| Solubility = 0.04 g/L (at 20 °C)
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| SolubleOther = Miscible with [[chloroform]], [[ethanol]], hydrocarbons
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| Solvent =
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| VaporPressure = 57.90 kPa (at 20.0 °C)
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| Viscosity = 0.240 cP (at 20 °C)
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  }}
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| Section4 = {{Chembox Thermochemistry
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| DeltaGf =
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| DeltaHc = −3,509,5–−3,508.5 kJ/mol
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| DeltaHf = −174.1–−172.9 kJ/mol
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| Entropy = 263.47 J·K<sup>−1</sup>·mol<sup>−1</sup>
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| HeatCapacity = 167.19 J·K<sup>−1</sup>·mol<sup>−1</sup>
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| Section5 = {{Chembox Explosive
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| ShockSens = Non-explosive
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| FrictionSens = Non-explosive
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| DetonationV = Non-explosive
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| REFactor = Non-explosive
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| Section6 = {{Chembox Hazards
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| AutoignitionPt = 260 °C (500 °F; 533 K)
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| ExploLimits = 1.5–7.8 %
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| ExternalMSDS = [https://www.boconline.co.uk/internet.lg.lg.gbr/en/images/sg-213-pentane410_39647.pdf?v=5.0 BOC]
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| FlashPt = −49 °C (-56.2 °F; 224 K)
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| LD50 = 3,000 mg/kg <small>(dermal, rabbit)</small><br>5,000 mg/kg <small>(oral, mouse)</small>
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| LC50 = 130,000 mg/m<sup>3</sup> (mouse, 30 min)<br/>128,200 ppm (mouse, 37 min)<br/>325,000 mg/m<sup>3</sup> (mouse, 2 hr)
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| MainHazards = Flammable<br>Volatile
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| Section7 = {{Chembox Related
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| OtherCompounds = [[Butane]]<br>[[Hexane]]
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  }}
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}}'''Pentane''' is an organic compound, an alkane with 5 carbon atoms, with the chemical formula '''C<sub>5</sub>H<sub>12</sub>'''. It is composed of three isomers, '''n-pentane''', [[isopentane]] (or methylbutane) and [[neopentane]]. While the term "pentane" may refer to any of the isomers, the IUPAC nomenclature specifies that the term must only be used for the n isomer.
  
 
==Properties==
 
==Properties==
 
===Chemical===
 
===Chemical===
−
PTFE is extremely resistant to chemical attacks, being only affected by molten alkali and strong fluorinating agents such as cobalt(III) fluoride and xenon difluoride. Teflon strips can burn in air, but it's most likely that the pyrolysis products are the one that catch fire.
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Pentane, like other hydrocarbons, will burn in air when ignited by an open flame to release [[carbon dioxide]] and [[water]] vapor.
 +
 
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: C<sub>5</sub>H<sub>12</sub> + 8 O<sub>2</sub> → 5 CO<sub>2</sub> + 6 H<sub>2</sub>O
 +
 
 +
Like other alkanes, pentane undergo [[free radical]] [[free radical halogenation|chlorination]]:
 +
 
 +
: C<sub>5</sub>H<sub>12</sub> + Cl<sub>2</sub> → C<sub>5</sub>H<sub>11</sub>Cl + 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 [[halogenation]]s can also occur.
  
 
===Physical===
 
===Physical===
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PTFE is a white solid at room temperature, with a melting point of 327 °C. Its density is 2.2 g/cm<sup>3</sup>. PTFE maintains mechanical properties down to temperatures of 5 K (−268.15 °C), and has good flexibility at temperatures above −79 °C. Teflon materials however are susceptible to creep. When melted, PTFE has the consistency of paste, so items can only be cast via injection.
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Pentane is a colorless liquid hydrocarbon, with a characteristic smell. It is insoluble in water, but miscible with other organic solvents. Pentane has a density of 0.621 g/cm<sup>3</sup>, meaning it's lighter than water. It boils at 36 °C and melts at -130 °C.
 +
 
 +
Its isomer neopentane, though, is a gas that boils at 9.5 °C, is the heaviest and the most high-boiling of all hydrocarbon gases.
  
 
==Availability==
 
==Availability==
−
PTFE is cheaply available as thread seal tapes. Many lab items, such as stoppers, gaskets, sleeves, [[magnetic stirrers]] are made of it and can be easily procured online. However, items made of PTFE are expensive, as PTFE cannot be molded like the more common type of plastics.
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Pentane can be purchased form chemical suppliers. Certain pesticides contain pentane.
 +
 
 +
Some car starter fluids contain pentane to increase the volatility of the fluid. You will need very a long fractional distillation column or repeated distillations to separate it from the mixture, as the boiling point of [[diethyl ether]] (34.6 °C), the other useful compound from starter fluid, is very close to that of pentane (36.3 °C). Additionally, you can add conc. [[sulfuric acid]] to separate the pentane from the ether (diethyl ether is soluble in conc. sulfuric acid, pentane is insoluble), then use a [[separatory funnel]] to remove the ether-acid and pentane layers. The ether can be recovered from the solution via distillation. This route however, is not very cost effective.
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 +
At least [http://www.hmdiffusion.com/rftp/sat/pdf/toprock_combustible_rechaud_essence_powerfuel_primus_fevrier2009.pdf one] type of charcoal lighter fluids can contain up to 25% n-pentane. Fractional distillation is required to extract the compound from the mixture.
  
 
==Preparation==
 
==Preparation==
−
PTFE is made via polymerization of tetrafluoroethylene. This process is difficult and expensive for the amateur chemist.
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Pentane can be prepared by decarboxylating the salts of caproic acid, found in various oily plants, with a strong base. Be careful, as the reaction may foam up.
  
 
==Projects==
 
==Projects==
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*[[Magnesium]]/PTFE flash powder
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*Extraction (solvent)
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*[[Ytterbium]]/PTFE emerald green composition with high IR output
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*Phthalic and maleic anhydride synthesis
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*Purification of organometallic compounds
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*Liquid chromatography
  
 
==Handling==
 
==Handling==
 
===Safety===
 
===Safety===
−
PTFE, being chemically inert, is non-toxic. Its pyrolysis is detectable at 200 °C, giving off fluorocarbon gases, that in large quantities can be dangerous for humans and are very toxic to wildlife, such as birds.
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Pentane, due to its low boiling point, evaporates very fast and the vapors are hazardous if inhaled, work should be performed in a fumehood or outside, never in a closed chamber without ventilation. If pentane is inhaled in large amounts, further exposure should be limited and one should seek fresh air.
 +
 
 +
Pentane is highly flammable and should be kept away from open flames.
  
 
===Storage===
 
===Storage===
−
No special storage is required.
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Due to its low boiling point, pentane should be stored in closed glass bottles, at constant temperature, away from any source of heat, even small ones. If it's stored at low temperatures, and then brought at room temperatures or slightly higher, pressure will build up in the bottle from the vapors and the bottle can explode. It is mandatory to open the bottle from time to time, to release the pressure.
 +
 
 +
Commercial pentane contains small amounts of inhibitors, that prevent its degradation, over long periods of time. They can be removed by distillation, as their boiling point is much higher than that of pentane.
  
 
===Disposal===
 
===Disposal===
−
Being chemically inert, PTFE poses hazard to the environment, as it cannot be digested by wildlife.
+
Pentane can be safely burned, as it theoretically should not generate any toxic byproducts. However, like other hydrocarbons, carbon monoxide can be formed so this should not be performed indoors.
  
 
==References==
 
==References==
 
<references/>
 
<references/>
 
===Relevant Sciencemadness threads===
 
===Relevant Sciencemadness threads===
 +
*[http://www.sciencemadness.org/talk/viewthread.php?tid=84471 Hexane or Pentane?]
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[[Category:Chemical compounds]]
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[[Category:Organic compounds]]
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[[Category:Hydrocarbons]]
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[[Category:Alkanes]]
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[[Category:Solvents]]
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[[Category:Nonpolar solvents]]
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[[Category:Volatile chemicals]]
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[[Category:Liquids]]

Latest revision as of 17:04, 14 October 2023

Pentane
Pentane sample.jpg
Distilled lab-grade pentane.
Names
IUPAC name
Pentane
Preferred IUPAC name
n-Pentane
Systematic IUPAC name
n-Pentane
Other names
Amyl hydride
Pentan
Skellysolve A
Identifiers
Jmol-3D images Image
Properties
C5H12
Molar mass 72.15 g/mol
Appearance Colorless volatile liquid
Odor Lighter-fluid like
Density 0.626 g/cm3
Melting point −129.8 °C (−201.6 °F; 143.3 K) (decomposes)
Boiling point 36 °C (97 °F; 309 K)
0.04 g/L (at 20 °C)
Solubility Miscible with chloroform, ethanol, hydrocarbons
Vapor pressure 57.90 kPa (at 20.0 °C)
Acidity (pKa) ~45
Viscosity 0.240 cP (at 20 °C)
Thermochemistry
263.47 J·K−1·mol−1
−174.1–−172.9 kJ/mol
Hazards
Safety data sheet BOC
Flash point −49 °C (-56.2 °F; 224 K)
Lethal dose or concentration (LD, LC):
3,000 mg/kg (dermal, rabbit)
5,000 mg/kg (oral, mouse)
130,000 mg/m3 (mouse, 30 min)
128,200 ppm (mouse, 37 min)
325,000 mg/m3 (mouse, 2 hr)
Related compounds
Related compounds
 Butane
Hexane
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
Pentane is an organic compound, an alkane with 5 carbon atoms, with the chemical formula C5H12. It is composed of three isomers, n-pentane, isopentane (or methylbutane) and neopentane. While the term "pentane" may refer to any of the isomers, the IUPAC nomenclature specifies that the term must only be used for the n isomer.

Properties

Chemical

Pentane, like other hydrocarbons, will burn in air when ignited by an open flame to release carbon dioxide and water vapor.

C5H12 + 8 O2 → 5 CO2 + 6 H2O

Like other alkanes, pentane undergo free radical chlorination:

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.

Physical

Pentane is a colorless liquid hydrocarbon, with a characteristic smell. It is insoluble in water, but miscible with other organic solvents. Pentane has a density of 0.621 g/cm3, meaning it's lighter than water. It boils at 36 °C and melts at -130 °C.

Its isomer neopentane, though, is a gas that boils at 9.5 °C, is the heaviest and the most high-boiling of all hydrocarbon gases.

Availability

Pentane can be purchased form chemical suppliers. Certain pesticides contain pentane.

Some car starter fluids contain pentane to increase the volatility of the fluid. You will need very a long fractional distillation column or repeated distillations to separate it from the mixture, as the boiling point of diethyl ether (34.6 °C), the other useful compound from starter fluid, is very close to that of pentane (36.3 °C). Additionally, you can add conc. sulfuric acid to separate the pentane from the ether (diethyl ether is soluble in conc. sulfuric acid, pentane is insoluble), then use a separatory funnel to remove the ether-acid and pentane layers. The ether can be recovered from the solution via distillation. This route however, is not very cost effective.

At least one type of charcoal lighter fluids can contain up to 25% n-pentane. Fractional distillation is required to extract the compound from the mixture.

Preparation

Pentane can be prepared by decarboxylating the salts of caproic acid, found in various oily plants, with a strong base. Be careful, as the reaction may foam up.

Projects

  • Extraction (solvent)
  • Phthalic and maleic anhydride synthesis
  • Purification of organometallic compounds
  • Liquid chromatography

Handling

Safety

Pentane, due to its low boiling point, evaporates very fast and the vapors are hazardous if inhaled, work should be performed in a fumehood or outside, never in a closed chamber without ventilation. If pentane is inhaled in large amounts, further exposure should be limited and one should seek fresh air.

Pentane is highly flammable and should be kept away from open flames.

Storage

Due to its low boiling point, pentane should be stored in closed glass bottles, at constant temperature, away from any source of heat, even small ones. If it's stored at low temperatures, and then brought at room temperatures or slightly higher, pressure will build up in the bottle from the vapors and the bottle can explode. It is mandatory to open the bottle from time to time, to release the pressure.

Commercial pentane contains small amounts of inhibitors, that prevent its degradation, over long periods of time. They can be removed by distillation, as their boiling point is much higher than that of pentane.

Disposal

Pentane can be safely burned, as it theoretically should not generate any toxic byproducts. However, like other hydrocarbons, carbon monoxide can be formed so this should not be performed indoors.

References

Relevant Sciencemadness threads

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