Degree of Unsaturation Calculator (DoU / IHD / DBE)

Your details

Number of carbon atoms in the molecular formula.
Number of hydrogen atoms in the molecular formula.
Number of nitrogen atoms. Each N adds 1 to the DoU numerator because a saturated amine requires one extra hydrogen per nitrogen.
Total count of all halogen atoms (F, Cl, Br, or I). Each halogen replaces one hydrogen, so it is subtracted like H.
Oxygen is divalent and does not change the hydrogen count of the saturated parent, so it has no effect on DoU. Enter it for your own reference.
Sulfur (like oxygen) is divalent and does not affect DoU. Enter it for your own reference.
Degree of Unsaturation (DoU)Possibly aromatic
4

Total number of rings and pi bonds in the molecule

Structure interpretationDoU = 4: a benzene ring accounts for exactly 4 (1 ring + 3 double bonds in Kekule form). Any compound with DoU = 4 is consistent with one phenyl group.
Maximum possible rings4
Maximum possible double bonds4
Saturated formula H count14
Hydrogen deficiency8
4 DoU
Saturated<1Unsaturated1-4Aromatic4-5Poly-unsaturated5-8Highly unsaturated8+

Degree of Unsaturation = 4.0 (consistent with one benzene ring)

  • DoU = 4 is the fingerprint of a benzene ring (one ring + three double bonds in the Kekule structure).
  • Many common aromatic compounds contain one or more phenyl groups, each contributing DoU = 4.
  • The saturated analogue would have the formula C6H14 (14 hydrogens). Your compound has 8 fewer.

Next stepPair DoU with IR (carbonyl, alkene, or alkyne peaks) and 1H NMR (aromatic signals near 7-8 ppm) to narrow down the structure.

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