Energetics of the 2+2 Cyclization of Limonene

Jonathan Filley, Alex Miedaner, Mohamed Ibrahim, Mark R. Nimlos, Daniel M. Blake

Research output: Contribution to journalArticlepeer-review

6 Scopus Citations


The hydrocarbon 1,2-dimethyltricyclo[,7]octane (4) was synthesized from carvone in two steps. Compound 4 is the product that would be obtained from the photochemical 2+2 intramolecular cyclization of limonene. The calculated enthalpy for the transformation of limonene to compound 4 is 7.2kcal/mol, the endothermicity of the reaction being attributed to ring strain in the product. This strain energy, accompanied by the increase in specific gravity obtained upon cyclization, gives compound 4 a larger heat of combustion, on a volumetric basis, than jet fuel. Other naturally occurring terpenes, which are inexpensive and abundant, bear consideration as starting materials for easily prepared high energy density materials.

Original languageAmerican English
Pages (from-to)17-21
Number of pages5
JournalJournal of Photochemistry and Photobiology A: Chemistry
Issue number1
StatePublished - 2001

NREL Publication Number

  • NREL/JA-590-29990


  • Camphor
  • Carvone
  • Fuel
  • Limonene
  • Photocyclization
  • Strain


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