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Degree of Unsaturation Calculator

Why calculate the degree of unsaturation?

A common problem in organic chemistry is trying to work out possible structural formulas for a compound having a particular molecular formula. As well as dictating the number and type of atoms in a compound, the molecular formula controls the number and types of bonds that are present. This calculator calculates the "degree of unsaturation" directly from the formula.

Why calculate the number of hydrogen atoms?

Stick structure are an extremely convenient for representing organic structures. However as the hydrogen atoms which are bonded to carbon are not shown on stick structures, it is common for mistakes to be made in working out the number of hydrogen atoms from the stick structure. This calculator can be used to obtain this number from the information which is easier to read from the structure: the number of carbon and heteroatoms and the "degree of unsaturation".

For a compound with formula CaHbNcOdXe where X is F, Cl, Br or I, the degree of unsaturation is given by:
degree of unsaturation = 1/2 (2 + 2a - b + c - e)
To calculate the degree of unsaturation, enter the values of a, b, c, d and e and press "calculate".

Alternatively, to calculate the number of hydrogen atoms, enter values for the degree of unsaturation, a, c, d and e and press "calculate".


Molcular Formula:





Degree of Unsaturation:

©2017 Dr Toby Hudson
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