Cyclopentane: Difference between revisions

|Verifiedimages = changed

|Watchedfields = changed

|verifiedrevid = 444653737

|ImageFileL1_Ref = {{chemboximage|correct|??}}

|ImageFileL1 = Cyclopentane v2.svg

|ImageSizeL1 = 100px

|ImageAltL1 = Skeletal formula

|ImageFileR1 = Cyclopentane3d.png

|ImageSizeR1 = 110px

|ImageAltR1 = Space-filling model

|PIN = Cyclopentane

|OtherNames = pentamethylene

|Section1 = {{Chembox Identifiers

|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

|ChemSpiderID = 8896

|InChI = 1/C5H10/c1-2-4-5-3-1/h1-5H2

|InChIKey = RGSFGYAAUTVSQA-UHFFFAOYAL

|StdInChI_Ref = {{stdinchicite|correct|chemspider}}

|StdInChI = 1S/C5H10/c1-2-4-5-3-1/h1-5H2

|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

|StdInChIKey = RGSFGYAAUTVSQA-UHFFFAOYSA-N

|CASNo_Ref = {{cascite|correct|CAS}}

|CASNo=287-92-3

|UNII_Ref = {{fdacite|correct|FDA}}

|UNII = T86PB90RNU

|PubChem=9253

|ChEBI_Ref = {{ebicite|correct|EBI}}

|ChEBI = 23492

|SMILES=C1CCCC1

|RTECS=GY2390000

|EINECS = 206-016-6

|Section2 = {{Chembox Properties

|Formula=C₅H₁₀

|MolarMass=70.1 g/mol

|Appearance=clear, colorless liquid

|Odor = mild, sweet

|Density=0.751 g/cm³

|MeltingPtC=-93.9

|BoilingPtC=49.2

|Solubility=156 mg·l⁻¹ (25 °C)<ref>{{GESTIS|ZVG=27960|CAS=287-92-3|Name=cyclopentane|Date=28 February 2015}}</ref>

|SolubleOther = soluble in [[ethanol]], [[acetone]], [[diethyl ether|ether]]

|pKa = ~45

|RefractIndex = 1.4065

|VaporPressure = 45 [[kPa]] (20 °C) <ref>{{cite web |url=http://www.ilo.org/dyn/icsc/showcard.display?p_version=2&p_card_id=0353 |title = ICSC 0353 - CYCLOPENTANE}}</ref>

|MagSus = -59.18·10⁻⁶ cm³/mol

}}

|Section3 = {{Chembox Hazards

|MainHazards=Flammable<ref name=PGCH/>

|FlashPtC = -37.2

|AutoignitionPtC = 361

|NFPA-H = 1 | NFPA-F = 3 | NFPA-R = 0

|PEL = none<ref name=PGCH>{{PGCH|0171}}</ref>

|ExploLimits = 1.1%-8.7%<ref name=PGCH/>

|IDLH = N.D.<ref name=PGCH/>

|REL = TWA 600 ppm (1720 mg/m³)<ref name=PGCH/>

}}

|Section4 = {{Chembox Related

|OtherCompounds = [[cyclopropane]], [[cyclobutane]], [[cyclohexane]]

}}

}}

'''Cyclopentane''' (also called '''C pentane''')<ref>{{cite journal |last1=Sárkány |first1=A. |last2=Gaál |first2=J. |last3=Toth |first3=L. |title=Comparative Study of C-Pentane and N-Pentane Transformations on Ni and Pt Catalysts |journal=Studies in Surface Science and Catalysis |date=1981 |volume=7 |pages=291–301 |doi=10.1016/S0167-2991(09)60278-0}}</ref> is a highly [[flammable]] [[alicyclic compound|alicyclic]] [[hydrocarbon]] with [[chemical formula]] [[C5H10|C₅H₁₀]] and [[CAS number]] 287-92-3, consisting of a ring of five [[carbon]] atoms each bonded with two [[hydrogen]] atoms above and below the plane. It occurs as a colorless [[liquid]] with a [[petrol]]-like [[odor]]. Its [[freezing point]] is −94 °C and its [[boiling point]] is 49 °C. Cyclopentane is in the class of [[cycloalkane]]s, being [[alkane]]s that have one or more [[carbon ring]]s. It is formed by [[cracking (chemistry)|cracking]] [[cyclohexane]] in the presence of [[alumina]] at a high temperature and pressure.

It was first prepared in 1893 by the German chemist [[Johannes Wislicenus]].<ref>{{cite journal |last1=Wislicenus |first1=J. |last2=Hentschel |first2=W. |title=III. Der Pentamethenylalkohol und seine Derivate (Cyclopentanol and its derivatives)|journal=Justus Liebigs Annalen der Chemie |date=January 1893 |volume=275 |issue=2-3 |pages=322–330 |doi=10.1002/jlac.18932750216 | url=http://babel.hathitrust.org/cgi/pt?id=mdp.39015026322613;view=1up;seq=332}}</ref>

==Production, occurrence and use==

Cycloalkanes are formed by [[catalytic reforming]]. For example, when passed over a hot platinum surface, [[2-Methylbutane|2-methylbutane]] converts into cyclopentane.

Cyclopentane is principally used as a [[blowing agent]] in the manufacture of [[polyurethane foam|polyurethane insulating foam]], replacing ozone-depleting agents such as [[Trichlorofluoromethane|CFC-11]] and [[1,1-Dichloro-1-fluoroethane|HCFC-141b]].<ref name="Schilling2000">{{cite journal | last1 = Schilling | first1 = S. L. | title = Appliance Rigid Foams Blown with Cyclopentane and Cyclopentane/Isopentane Blends | journal = Journal of Cellular Plastics | date = May 2000 | volume = 36 | issue = 3 | pages = 190–206 | issn = 0021-955X | eissn = 1530-7999 | doi = 10.1177/0021955X0003600302 | pmid = | url = }}</ref><ref name=greenpeace>[http://archive.greenpeace.org/ozone/excuse/20excuse.html Greenpeace - Appliance Insulation] {{webarchive|url=https://web.archive.org/web/20081030041552/http://archive.greenpeace.org/ozone/excuse/20excuse.html |date=2008-10-30 }}</ref> While cyclopentane is not typically used as a [[refrigerant]], it is common for domestic appliances that are insulated with cyclopentane-based foam, such as [[refrigerator]]s and [[freezer]]s, to be marked with cyclopentane warning labels due to its flammability. Cyclopentane is also used in the manufacture of [[chemical synthesis|synthetic]] [[resin]]s and [[rubber]] [[adhesive]]s.{{Citation needed|date=June 2024}}

Multiply alkylated cyclopentane (MAC) lubricants, such as 1,3,4-tri-(2-octyldodecyl) cyclopentane, have low volatility and are used by NASA in space applications.<ref name="NASA">{{cite tech report |last1=Loewenthal |first1=Stuart H. |last2=Jones |first2=William R. |last3=Predmore |first3=Roamer E. |title=Life of Pennzane and 815Z-Lubricated Instrument Bearings Cleaned with Non-CFC Solvents |date=1 September 1999 |url=https://ntrs.nasa.gov/citations/19990039657 |publisher=National Aeronautics and Space Administration |location=John H. Glenn Research Center at Lewis Field |language=en |oclc=1002210567 |id=19990039657 }}</ref><ref>{{cite web | title=Pennzoil Products: High Tech Products | website=pennzane.com | date=12 April 2004 | url=http://pennzane.com/ | archive-url=https://web.archive.org/web/20040412141718/http://pennzane.com/ | archive-date=12 April 2004 | url-status=dead | access-date=15 July 2022}}</ref>

Cyclopentane requires safety precautions to prevent leakage and ignition as it is both highly flammable and can also cause respiratory arrest when inhaled.<ref>{{cite journal | author=Robert W. Virtue, M.D. | title=OBSERVATIONS ON CYCLOPENTANE AS AN ANESTHETIC AGENT | journal=Anesthesiology | volume=10 | date=May 1949 | pages=318–324 | doi=10.1097/00000542-194905000-00007}}</ref>

Cyclopentane can be fluorinated to give compounds ranging from {{chem2|C5H9F}} to [[perfluorocyclopentane]] {{chem2|C5F10}}. Such species are conceivable refrigerants and specialty solvents.<ref name="Tatlow 1995">{{cite journal | last=Tatlow | first=John Colin | title=Cyclic and bicyclic polyfluoro-alkanes and -alkenes | journal=Journal of Fluorine Chemistry | volume=75 | issue=1 | year=1995 | issn=0022-1139 | doi=10.1016/0022-1139(95)03293-m | pages=7–34}}</ref><ref>{{cite journal |last1=Zhang |first1=Chengping |last2=Qing |first2=Feiyao |last3=Quan |first3=Hengdao |last4=Sekiya |first4=Akira |title=Synthesis of 1,1,2,2,3,3,4-heptafluorocyclopentane as a new generation of green solvent |journal=Journal of Fluorine Chemistry |date=January 2016 |volume=181 |pages=11–16 |doi=10.1016/j.jfluchem.2015.10.012}}</ref>

The cyclopentane ring is pervasive in [[natural product]]s including many useful drugs. Examples include most [[steroid]]s, [[prostaglandin]]s, and some [[lipid]]s.

==Conformations==

In a [[regular pentagon]], the angles at the vertices are all 108°, slightly less than the bond angle in perfectly tetrahedrally bonded carbon, which is about 109.47°. However, cyclopentane is not planar in its normal [[Conformational isomerism|conformations]]. It puckers in order to increase the distances between the hydrogen atoms (something which does not happen in the planar [[cyclopentadienyl anion]] {{chem2|C5H5-}} because it doesn't have as many hydrogen atoms). This means that the average C-C-C angle is less than 108°. There are two conformations that give local minima of the energy, the "envelope" and the "half-chair". The envelope has mirror symmetry ([[Point groups in three dimensions|C{{sub|s}}]]), while the half chair has two-fold rotational symmetry ([[Point groups in three dimensions|C{{sub|2}}]]). In both cases the symmetry implies that there are two pairs of equal C-C-C angles and one C-C-C angle that has no pair. In fact for cyclopentane, unlike for [[cyclohexane]] (C₆H₁₂, see [[cyclohexane conformation]]) and higher [[cycloalkane]]s, it is not possible geometrically for all the angles and bond lengths to be equal except if it is in the form of a flat regular pentagon.

<gallery>

File:Cyclopentane envelope conformation.svg|Envelope

File:Cyclopentane3D.png|3D envelope

File:Cyclopentane halfchair.svg|Half-chair

</gallery>

==External links==

*{{Commons category-inline|Cyclopentane}}

{{Authority control}}

[[Category:Cyclopentanes]]

[[Category:Cycloalkanes]]