Question
Calculate the degree of unsaturation in each of the following formulas:
(a)
(b)
(c)
(d)
(e)
(f)
Answer
In organic structure problems, the quantity intended by “degree of saturation formula” is usually the degree of unsaturation, also called DBE or IHD. For the neutral, ordinary-valence formulas in this exercise,
where count carbon, hydrogen and nitrogen atoms, and counts all halogens. Oxygen does not enter this expression.
Calculate each formula
| Part | Molecular formula | Substitution into the formula | DBE |
|---|---|---|---|
| (a) | 5 | ||
| (b) | 5 | ||
| (c) | 3 | ||
| (d) | 1 | ||
| (e) | 6 | ||
| (f) | 5 |
Thus the ordered answers are 5, 5, 3, 1, 6, 5.
What these numbers establish
Each ring contributes one DBE, each double bond contributes one, and each triple bond contributes two. For example, the value 1 in (d) allows one ring or one double bond; the molecular formula alone does not distinguish them. The exercise requests the six counts, not a unique structure.
This organic-chemistry calculation is not the soil-mechanics degree of saturation , which measures the fraction of void space occupied by water. Nor should the neutral-formula DBE expression be applied blindly to ions or unusual valence states.
Evidence boundary
The six formulas and their order are from OpenStax Problem 7-2. This page interprets the search phrase in its organic-chemistry context as degree of unsaturation, not soil saturation. The results count rings and multiple-bond equivalents for ordinary neutral formulas; they do not determine unique molecular structures or establish aromaticity.
Sources
These references support the concepts and methods used in the explanation above.