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.

Isomers

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

Synthesis

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.

Occurrence

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

Reactions

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

Safety

Decalin easily forms explosive hydroperoxides upon storage in the presence of air.

See also