Degree of Unsaturation Calculator

The degree of unsaturation (also known as the index of hydrogen deficiency or IHD) is a calculation used in organic chemistry to determine the total number of rings, double bonds, or triple bonds in a molecule. It compares the number of hydrogen atoms a molecule has to the maximum number of hydrogen atoms a fully saturated hydrocarbon (alkane) would have, given the same number of carbon atoms.

The Formula:

Degere of unsateration = U = C + 1 - 1/2(X-N)
​

Where:

• C = number of carbon atoms
• H = number of hydrogen atoms
• N = number of nitrogen atoms
• X = number of halogen atoms (F, Cl, Br, I)

Each double bond or ring removes 2 hydrogens from a molecule compared to a fully saturated alkane, while each triple bond removes 4 hydrogens. By calculating the degree of unsaturation, you can infer how many rings and/or multiple bonds are present in the molecule.

Why It's Important:

1. Structural Clues: The degree of unsaturation helps chemists predict molecular structure. A degree of 0 indicates a fully saturated molecule (no rings or double bonds), while higher values suggest the presence of unsaturated features like rings or multiple bonds.

2. Guiding Molecular Elucidation: When analyzing molecules, especially in unknown compounds, calculating unsaturation helps narrow down possible structures by providing insight into bonding patterns.

Example Calculations:

• Benzene (C₆H₆):

  • Degree of Unsaturation = $(2(6)+2-6)/2=4$
  • This value of 4 indicates that benzene has 3 double bonds and 1 ring.

• Cyclohexane (C₆H₁₂):

  • Degree of Unsaturation = $(2(6)+2-12)/2=1$
  • This value of 1 indicates the presence of one ring.

Degree of Unsaturation Calculator

By analyzing the degree of unsaturation, organic chemists gain quick insight into a molecule's structure, which is fundamental in understanding and predicting chemical behavior.

Enter a molecular formula (e.g., C6H6, C4H9Br, etc.):

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