Decalin

Decalin

Decalin

Chemical compound

Decalin (decahydronaphthalene, also known as bicyclo[4.4.0]decane and sometimes decaline),[3] a bicyclic organic compound, is an industrial solvent. A colorless liquid with an aromatic odor, it is used as a solvent for many resins or fuel additives.[4]

Quick Facts Names, Identifiers ...

Isomers

Decalin occurs in cis and trans forms. The trans form is energetically more stable because of fewer steric interactions. cis-Decalin is a chiral molecule without a chiral center; it has a two-fold rotational symmetry axis, but no reflective symmetry. However, the chirality is canceled through a chair-flipping process that turns the molecule into its mirror image.

  • 1: trans (left) and cis (right) isomers
  • 2:
    ball-and-stick model of cis-decalin
  • 3:
    trans-decalin
  • 4:
    cis-decalin ring-flip

trans-Decalin

The only possible way to join the two six-membered rings in the trans position means the second ring needs to start from two equatorial bonds (blue) of the first ring. A six-membered ring does not offer sufficient space to start out on an axial position (upwards), and reach the axial position of the neighboring carbon atom, which then will be on the downwards side of the molecule (see the model of cyclohexane in figure 5). The structure is conformationally frozen. It does not have the ability to undergo a chair flip as in the cis isomer. In biology this fixation is widely used in the steroid skeleton to construct molecules (such as figure 6) that play a key role in the signalling between distantly separated cells.

Reactions

Oxygenation of decalin gives the tertiary hydroperoxide, which rearranges to cyclodecenone, a precursor to sebacic acid.[5]

Decalin is the saturated analog of naphthalene and can be prepared from it by hydrogenation in the presence of a catalyst. This interconversion has been considered in the context of hydrogen storage.[6]

Derivation

Treatment of naphthalene in a fused state with hydrogen in the presence of a copper or nickel catalyst. [7]


Occurrence

Decalin itself is rare in nature but several decalin derivatives are known. They arise via terpene-derived precursors or polyketides.[8]

Safety

Decalin easily forms explosive[9] hydroperoxides upon storage in the presence of air.[10][11]


See also

References

  1. [1]
    Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. pp. 33, 394, 601. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
  2. [2]
    Haynes, William M. (2010). Handbook of Chemistry and Physics (91 ed.). Boca Raton, Florida, USA: CRC Press. p. 3-134. ISBN 978-1-43982077-3.
  3. [3]
    "Dictionary.com".
  4. [4]
    "Fuel Additive Product". Archived from the original on 2009-03-12.
  5. [5]
    Griesbaum, Karl; Behr, Arno; Biedenkapp, Dieter; Voges, Heinz-Werner; Garbe, Dorothea; Paetz, Christian; Collin, Gerd; Mayer, Dieter; Höke (2000). "Hydrocarbons". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a13_227. ISBN 978-3527306732.
  6. [6]
    Isa, Khairuddin Md; Abdullah, Tuan Amran Tuan; Ali, Umi Fazara Md (2018). "Hydrogen donor solvents in liquefaction of biomass: A review". Renewable and Sustainable Energy Reviews. 81: 1259–1268. doi:10.1016/j.rser.2017.04.006.
  7. [7]
    [Hawley's Condensed Chemical Dictionary]
  8. [8]
    Li, Gang; Kusari, Souvik; Spiteller, Michael (2014). "Natural products containing 'decalin' motif in microorganisms". Nat. Prod. Rep. 31 (9): 1175–1201. doi:10.1039/C4NP00031E. PMID 24984916.
  9. [9]
    "PDF – Surrogate JP-8 Aviation Fuel Study – Alessandro Agosta Thesis Drexel University" (PDF). Archived from the original (PDF) on 2010-06-19.
  10. [10]
    "Inchem.org Data".
  11. [11]
    "MSDS Sheet – JT Baker".
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