Free Degree of Unsaturation Calculator
Calculate the degree of unsaturation (index of hydrogen deficiency) from a molecular formula containing C, H, N, and halogens.
Degrees of Unsaturation
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Degrees of Unsaturation vs Number of Carbons (C)
Degree of Unsaturation (Index of Hydrogen Deficiency)
The degree of unsaturation tells how many rings and/or double bonds are in a molecule. Each ring or double bond reduces the hydrogen count by 2 relative to the fully saturated formula.
Formula
DoU = (2C + 2 + N - H - X) / 2
where C = carbons, H = hydrogens, N = nitrogens, X = halogens. Oxygen and sulfur are not included because they do not change the hydrogen count. A DoU of 4 for a C6 compound suggests a benzene ring.
Example Calculation
Calculate the degree of unsaturation for benzene (C6H6).
- 01DoU = (2 × 6 + 2 + 0 - 6 - 0) / 2
- 02DoU = (12 + 2 - 6) / 2 = 8 / 2 = 4
- 03Benzene has 3 double bonds + 1 ring = 4 DoU
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