Decalin (decahydronaphthalene, also known as bicyclo[4.4.0]decane and sometimes decaline), 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.^[6]

Decalin occurs in cis and trans forms. The trans form is energetically more stable because of fewer steric effects. 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.^{[citation needed]}

• 
  1: trans (left) and cis (right) isomers
• 
  2:

  ball-and-stick model of cis-decalin
• 
  3:

  trans-decalin
• 
  4:

  cis-decalin ring-flip

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.^[7]

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

Oxygenation of decalin gives the tertiary hydroperoxide, which rearranges via hydroxycyclodecanone to cyclodecenone, a precursor to sebacic acid.^[9]

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

• Dialin
• Geosmin
• Perfluorodecalin