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ⓘ Degree of unsaturation. Subtract the total from above from the number of hydrogens actually present. Determine the number of hydrogens that should be present if ..




Degree of unsaturation
                                     

ⓘ Degree of unsaturation

  • Subtract the total from above from the number of hydrogens actually present.
  • Determine the number of hydrogens that should be present if it was completely single bonded. In other words use the formula 2n+2 with n = the number of carbons present.
  • Take that number and divide it by two. This number is your DOU.

Each degree either equals one ring structure or pi bond. A double bond would have one DOU. A triple bond would have a DOU of two triple bond is one sigma bond with two pi bonds.

                                     

1. Non-hydrocarbons

For the below, use the same rules as above, using the definitions below.

  • Halogens Group 7 count as a hydrogen
  • Boron, nitrogen and phosphorus each count as a "half a carbon"
  • Silicon counts as a carbon
  • Oxygen, sulfur and selenium Group 6 can be ignored