Index of Hydrogen Deficiency (continued)

• Each Pi bond = Index of 1

• Each ring = index of 1 (For satructural differences only) (Does not take up H2)

• Examples (Problem 7.5 7.6)

  • alkene I = 1 (takes up 1 mole H2)
  • alkyne I = 2 (Takes up 2 moles H2)
  • cycloalkene I = 2 (Takes up 1 mole H2)
  • alkenyne I= 3 (Takes up 3 mole H2)

Previous slide

Next slide

Back to first slide

View graphic version

Examples of Application of Index

1. Given the number of carbons in the hydrocarbon and the Index of Hydrogen Deficiency, determine the molecular formula

Example: What is the molecular formula of an eight carbon hydrocarbon with an Index of 3?

2. Given the number of carbons in the hydrocarbon and the Index, speculate on what kind of hydrocarbon it is in terms of unsaturation.

Example:Speculate on the possible structure of a hydrocarbon of 6 carbons and an index of 2.