Definition of Hydrogen Deficiency Index

Hydrogen deficiency index is a term that is used for hydrocarbons. The hydrocarbons may be saturated (having all single bonds) or unsaturated (having double or triple bonds). There is a maximum number of hydrogen atoms if the molecule is saturated. On the other hand, the unsaturated hydrocarbons are deficient in hydrogen atoms.


Index of hydrogen deficiency (IHD) is also known as the degree of unsaturation. This gives us the clue to determine the number of double and triple bonds present in the hydrocarbon molecule and if there is any ring involved in the molecule. If the hydrocarbon is composed of a ring or has a double bond, then IHD is one whereas if there are triple bonds present in the molecule, then IHD is two.




Formula of Hydrogen Deficiency Index:

It can be calculated by the following formula:

Hydrogen Deficiency Index Formula

Where x represents the number of carbon atoms and y represents the number of hydrogen atoms present in a molecule.

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