Pentane

Pentane

Names
Preferred IUPAC name Pentane
Other names Quintane[1]
Identifiers
CAS Number	109-66-0 Y
3D model (JSmol)	Interactive image
Beilstein Reference	969132
ChEBI	CHEBI:37830 Y
ChEMBL	ChEMBL16102 Y
ChemSpider	7712 Y
DrugBank	DB03119 Y
ECHA InfoCard	100.003.358
EC Number	203-692-4
Gmelin Reference	1766
MeSH	pentane
PubChem CID	8003
RTECS number	RZ9450000
UNII	4FEX897A91 Y
UN number	1265
InChI InChI=1S/C5H12/c1-3-5-4-2/h3-5H2,1-2H3 Y Key: OFBQJSOFQDEBGM-UHFFFAOYSA-N Y
SMILES CCCCC
Properties[3]
Chemical formula	C5H12
Molar mass	7001721510000000000♠72.151 g·mol−1
Appearance	Colourless liquid
Odor	Gasoline-like[2]
Density	0.626 g mL−1; 0.6262 g mL−1 (at 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
Solubility in water	40 mg L−1 (at 20 °C)
log P	3.255
Vapor pressure	57.90 kPa (at 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
Magnetic susceptibility (χ)	-63.05·10−6 cm3/mol
Refractive index (nD)	1.358
Viscosity	0.240 mPa·s (at 20 °C)
Thermochemistry
Heat capacity (C)	167.19 J K−1 mol−1
Std molar entropy (So298)	263.47 J K−1 mol−1
Std enthalpy of formation (ΔfHo298)	−174.1–−172.9 kJ mol−1
Std enthalpy of combustion (ΔcHo298)	−3.5095–−3.5085 MJ mol−1
Hazards
Safety data sheet	See: data page
GHS pictograms
GHS signal word	DANGER
GHS hazard statements	H225, H304, H336, H411
GHS precautionary statements	P210, P261, P273, P301+310, P331
NFPA 704	4 1 0
Flash point	−49.0 °C (−56.2 °F; 224.2 K)
Autoignition temperature	260.0 °C (500.0 °F; 533.1 K)
Explosive limits	1.5–7.8%[2]
Lethal dose or concentration (LD, LC):
LD50 (median dose)	3 g kg−1(dermal, rabbit) 5 g kg−1(oral, mouse)
LC50 (median concentration)	130,000 mg/m3 (mouse, 30 min) 128,200 ppm (mouse, 37 min) 325,000 mg/m3 (mouse, 2 hr)[4]
US health exposure limits (NIOSH):
PEL (Permissible)	TWA 1000 ppm (2950 mg/m3)[2]
REL (Recommended)	TWA 120 ppm (350 mg/m3) C 610 ppm (1800 mg/m3) [15-minute][2]
IDLH (Immediate danger)	1500 ppm[2]
Related compounds
Related alkanes	Butane Butyl iodide Hexane
Supplementary data page
Structure and properties	Refractive index (n), Dielectric constant (εr), etc.
Thermodynamic data	Phase behaviour solid–liquid–gas
Spectral data	UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
Infobox references

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; 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.

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.

Contents

• 
  1 Industrial uses
  


• 
  2 Laboratory use
  


• 
  3 Physical properties
  


• 
  4 Reactions
  


• 
  5 References
  


• 
  6 External links
  

Industrial uses

Pentanes are some of the primary blowing agents used in the production of polystyrene foam and other foams. Usually, a mixture of n-, i-, and increasingly cyclopentane is used for this purpose.

Acid-catalyzed isomerization gives isopentane, which is used in producing high-octane fuels.^[5]

Because of their low boiling points, low cost, and relative safety, pentanes are used as a working medium in geothermal power stations in some blended refrigerants also used as a working medium in organic rankine cycles.

Pentanes are solvents in many ordinary products, e.g. in some pesticides.^[6]

Laboratory use

Pentanes are relatively inexpensive and are the most volatile liquid alkanes at room temperature, so they are often used in the laboratory as solvents that can be conveniently and rapidly evaporated. However, because of their nonpolarity and lack of functionality, they dissolve only nonpolar and alkyl-rich compounds. Pentanes are miscible with most common nonpolar solvents such as chlorocarbons, aromatics, and ethers.

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. But this explanation is contradicted by the fact that neopentane has a lower density than the other two isomers.^[7]

The branched isomers are more stable (have lower heat of formation and heat of combustion) than n-pentane. The difference is 1.8 kcal/mol for isopentane, and 5 kcal/mol for neopentane.^[8]

Rotation about two central single C-C bonds of n-pentane produces four different conformations.^[9]

Reactions

Like other alkanes, pentanes are largely unreactive at standard room temperature and conditions - however, with sufficient activation energy (i.e. an open flame), they readily oxidize to form carbon dioxide and water:

C₅H₁₂ + 8 O₂ → 5 CO₂ + 6 H₂O + heat/energy

Like other alkanes, pentanes 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.

References

1. 
   ^ 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. Retrieved 4 April 2018 – via rspl.royalsocietypublishing.org..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output .citation q{quotes:"""""""'""'"}.mw-parser-output .citation .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .citation .cs1-lock-limited a,.mw-parser-output .citation .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .citation .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Wikisource-logo.svg/12px-Wikisource-logo.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-maint{display:none;color:#33aa33;margin-left:0.3em}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}
   


2. 
   ^ ^abcde NIOSH Pocket Guide to Chemical Hazards. "#0486". National Institute for Occupational Safety and Health (NIOSH).
   


3. 
   ^ Record of n-Pentane in the GESTIS Substance Database of the Institute for Occupational Safety and Health, accessed on 19 April 2011.
   


4. 
   ^ "n-Pentane". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
   


5. 
   ^ Karl Griesbaum, Arno Behr, Dieter Biedenkapp, Heinz-Werner Voges, Dorothea Garbe, Christian Paetz, Gerd Collin, Dieter Mayer, Hartmut Höke (2002). "Hydrocarbons". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a13_227. ISBN 978-3527306732.CS1 maint: Uses authors parameter (link)
   


6. 
   ^ Milne, ed., G.W.A. (2005). Gardner's Commercially Important Chemicals: Synonyms, Trade Names, and Properties. Hoboken, New Jersey: John Wiley & Sons, Inc. p. 477. ISBN 978-0-471-73518-2.CS1 maint: Extra text: authors list (link)
   


7. 
   ^
   James Wei (1999), Molecular Symmetry, Rotational Entropy, and Elevated Melting Points. Ind. Eng. Chem. Res., volume 38 issue 12, pp. 5019–5027 doi:10.1021/ie990588m
   


8. 
   ^ From the values listed at Standard enthalpy change of formation (data table).
   


9. 
   ^ Roman M. Balabin (2009). "Enthalpy Difference between Conformations of Normal Alkanes: Raman Spectroscopy Study of n-Pentane and n-Butane". J. Phys. Chem. A. 113 (6): 1012–9. doi:10.1021/jp809639s. PMID 19152252.
   

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

v t e Alkanes
Methane (CH 4) Ethane (C 2H 6) Propane (C 3H 8) Butane (C 4H 10) Pentane (C 5H 12) Hexane (C 6H 14) Heptane (C 7H 16) Octane (C 8H 18) Nonane (C 9H 20) Decane (C 10H 22) Undecane (C 11H 24) Dodecane (C 12H 26) Tridecane (C 13H 28) Tetradecane (C 14H 30) Pentadecane (C 15H 32) Hexadecane / Cetane (C 16H 34) Heptadecane (C 17H 36) Octadecane (C 18H 38) Nonadecane (C 19H 40) Icosane (C 20H 42) Heneicosane (C 21H 44) Tetracosane (C 24H 50) Nonacosane (C 29H 60) 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 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 Dihydrides BeH2 MgH2 CaH2 SrH2 BaH2
Group 13 hydrides	Boranes BH3 B2H6 B2H2 B2H4 B4H10 B5H9 B5H11 B6H10 B6H12 B10H14 B18H22 Alanes AlH3 Al2H6 Gallanes GaH3 Ga2H6 Indiganes InH3 In2H6 Thallanes TlH3 Tl2H6
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 SiH 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 LaH10 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 AmH2 AmH3 CmH2

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