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Pentane
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
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
Laboratory
use 3 Physical properties 4 Reactions 5 References 6 External links

Industrial uses[edit] 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. Because of its low boiling point, low cost, and relative safety, pentanes are used as a working medium in geothermal power stations in some blended refrigerants. Pentanes are also an active ingredient in some pesticides.[5] Laboratory
Laboratory
use[edit] 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 non-polar 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[edit] 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.[6] 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.[7] Rotation
Rotation
about two central single C-C bonds of n-pentane produces four different conformations.[8] Reactions[edit] 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[edit]

^ 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.  ^ a b c d e "NIOSH Pocket Guide to Chemical Hazards #0486". National Institute for Occupational Safety and Health (NIOSH).  ^ Record of n- Pentane
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 and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).  ^ 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) ^ 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 ^ From the values listed at Standard enthalpy change of formation (data table). ^ Roman M. Balabin (2009). "Enthalpy Difference between Conformations of Normal Alkanes: Raman Spectroscopy Study of n- Pentane
Pentane
and n-Butane". J. Phys. Chem. A. 113 (6): 1012–9. doi:10.1021/jp809639s. PMID 19152252. 

External links[edit]

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

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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

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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
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
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
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 P

.