Illustrated Glossary of Organic Chemistry
Double bond equivalent (DBE; UN; degree of unsaturation; PBoR [Pi Bonds or Rings]): The number of molecules of H2 that would have to be added to a molecule to convert all pi bonds to single bonds, and all rings to acyclic structures. The DBE number can be calculated from the formula using the following equation:
See Also
What is Bond Yield?DBE = UN = PBoR = C - (H/2) + (N/2) +1,
where: C = number of carbon atoms, H = number of hydrogen and halogen atoms, and N = number of nitrogen atoms.
One DBE = one ring or one double bond. Two DBE = two rings, two double bonds, or one triple bond, or one ring plus one double bond. A benzene ring requires four DBE (one for the ring plus one for each C=C).
![Illustrated Glossary of Organic Chemistry
equivalent (DBE; UN; degree of unsaturation; PBoR [Pi Bonds or
Rings]) (2024)](data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mP8/h8AAvMB+NzmkbcAAAAASUVORK5CYII=)
