Methylcyclopentane

Methylcyclopentane
Names
Preferred IUPAC name
Methylcyclopentane
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.002.277 Edit this at Wikidata
EC Number
  • 202-503-2
UNII
UN number 2298
  • InChI=1S/C6H12/c1-6-4-2-3-5-6/h6H,2-5H2,1H3
  • CC1CCCC1
Properties
C6H12
Molar mass 84.162 g·mol−1
Appearance Colorless liquid
Density 0.749 g/cm3[1]
Melting point −142.4 °C (−224.3 °F; 130.8 K)[1]
Boiling point 71.8 °C (161.2 °F; 344.9 K)[1]
Insoluble
-70.17·10−6 cm3/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 flammable
Flash point −4 °C (25 °F; 269 K)
260 °C (500 °F; 533 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Methylcyclopentane is an organic compound with the chemical formula CH3C5H9. It is a colourless, flammable liquid with a faint odor. It is a component of the naphthene fraction of petroleum usually obtained as a mixture with cyclohexane. It is mainly converted in naphthene reformers to benzene.[2]

As of early 1990s, it was present in American[3] and European[4] gasoline in small amounts, and by 2011 its share in US gasoline varied between 1 and 3%.[5] It has a research octane number of 103 and motor octane number of 95.[6]

The C6 core of methylcyclopentane is not perfectly planar and can pucker to alleviate stress in its structure.[7]

The conversion of methylcyclopentane to benzene is a classic aromatization reaction, specifically a dehydroisomerization. This platinum (Pt)-catalyzed process is practiced on scale in the production of gasoline from petroleum.

History

Methylcyclopentane was first synthesized in 1888 by Paul Caspar Freer [Wikidata] and W. H. Perkin Jr. by a Wurtz reaction of sodium and 1,5-dibromohexane.[8] They named it methylpentamethylene since the modern nomenclature wasn't developed until 1892 Geneva Rules.

In 1895, Nikolai Kischner discovered that methylcyclopentane was the reaction product of hydrogenation of benzene using hydriodic acid. Prior to that, several chemists (such as Marcellin Berthelot in 1867,[9][10] and Adolf von Baeyer in 1870[11]) had tried and failed to synthesize cyclohexane using this method.

References

  1. ^ a b c Lide, David. R, ed. (2009). CRC Handbook of Chemistry and Physics (89th ed.). CRC Press. ISBN 978-1-4200-6679-1.
  2. ^ M. Larry Campbell (2012). "Cyclohexane". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a08_209.pub2. ISBN 978-3527306732.
  3. ^ Doskey, Paul V.; Porter, Joseph A.; Scheff, Peter A. (November 1992). "Source Fingerprints for Volatile Non-Methane Hydrocarbons". Journal of the Air & Waste Management Association. 42 (11): 1437–1445. doi:10.1080/10473289.1992.10467090. ISSN 1047-3289.
  4. ^ Östermark, Ulf; Petersson, Göran (1992-09-01). "Assessment of hydrocarbons in vapours of conventional and alkylate-based petrol" (PDF). Chemosphere. 25 (6): 763–768. doi:10.1016/0045-6535(92)90066-Z. ISSN 0045-6535.
  5. ^ "Hydrocarbon Composition of Gasoline Vapor Emissions from Enclosed Fuel Tanks". nepis.epa.gov. United States Environmental Protection Agency. 2011.
  6. ^ Lokachari, Nitin; Wagnon, Scott W.; Kukkadapu, Goutham; Pitz, William J.; Curran, Henry J. (2021-03-01). "An experimental and kinetic modeling study of cyclopentane and dimethyl ether blends". Combustion and Flame. 225: 255–271. doi:10.1016/j.combustflame.2020.10.017. hdl:10379/16483. ISSN 0010-2180.
  7. ^ Carey, Francis; Giuliano, Robert (2014). "3". Organic Chemistry (9 ed.). McGraw-Hill. pp. 97–131. ISBN 978-0073402741.
  8. ^ Freer, Paul C.; Perkin, W. H. (1888). "The synthetical formation of closed carbon-chains. Part IV. Some derivatives of hexamethylene". Journal of the Chemical Society, Transactions. 53 (0): 202–215. doi:10.1039/CT8885300202. ISSN 0368-1645.
  9. ^ Bertholet (1867). "Nouvelles applications des méthodes de réduction en chimie organique" [New applications of reduction methods in organic chemistry]. Bulletin de la Société Chimique de Paris (in French). series 2 (7): 53–65.
  10. ^ Bertholet (1868). "Méthode universelle pour réduire et saturer d'hydrogène les composés organiques" [Universal method for reducing and saturating organic compounds with hydrogen]. Bulletin de la Société Chimique de Paris (in French). series 2 (9): 8–31. En effet, la benzine, chauffée à 280° pendant 24 heures avec 80 fois son poids d'une solution aqueuse saturée à froid d'acide iodhydrique, se change à peu près entièrement en hydrure d'hexylène, C12H14, en fixant 4 fois son volume d'hydrogène: C12H6 + 4H2 = C12H14 … Le nouveau carbure formé par la benzine est un corps unique et défini: il bout à 69°, et offre toutes les propriétés et la composition de l'hydrure d'hexylène extrait des pétroles. [In effect, benzene, heated to 280° for 24 hours with 80 times its weight of an aqueous solution of cold saturated hydroiodic acid, is changed almost entirely into hydride of hexylene, C12H14, [Note: this formula for hexane (C6H14) is wrong because chemists at that time used the incorrect atomic mass for carbon.] by fixing [i.e., combining with] 4 times its volume of hydrogen: C12H6 + 4H2 = C12H14 The new carbon compound formed by benzene is a unique and well-defined substance: it boils at 69° and presents all the properties and the composition of hydride of hexylene extracted from oil.)]
  11. ^ Adolf Baeyer (1870). "Ueber die Reduction aromatischer Kohlenwasserstoffe durch Jodphosphonium" [On the reduction of aromatic compound by phosphonium iodide [H4IP]]. Annalen der Chemie und Pharmacie. 55: 266–281. Bei der Reduction mit Natriumamalgam oder Jodphosphonium addiren sich im höchsten Falle sechs Atome Wasserstoff, und es entstehen Abkömmlinge, die sich von einem Kohlenwasserstoff C6H12 ableiten. Dieser Kohlenwasserstoff ist aller Wahrscheinlichkeit nach ein geschlossener Ring, da seine Derivate, das Hexahydromesitylen und Hexahydromellithsäure, mit Leichtigkeit wieder in Benzolabkömmlinge übergeführt werden können. [During the reduction [of benzene] with sodium amalgam or phosphonium iodide, six atoms of hydrogen are added in the extreme case, and there arise derivatives, which derive from a hydrocarbon C6H12. This hydrocarbon is in all probability a closed ring, since its derivatives — hexahydromesitylene [1,3,5 - trimethyl cyclohexane] and hexahydromellithic acid [cyclohexane-1,2,3,4,5,6-hexacarboxylic acid] — can be converted with ease again into benzene derivatives.]