2 Summary Tables
2.1 General Tables
2.1.1 Calculation of the Number of Double Bond Equivalents from
the Molecular Formula
General Equation
double bond equivalents = 1 + ½ ∑
i
n i (v i - 2)
n i : number of atoms of element i in molecular formula
v i : formal valence of element i
Short Cut
For compounds containing only C, H, O, N, S, and halogens, the following steps
permit a quick and simple calculation of the number of double bond equivalents:
1. O and divalent S are deleted from the molecular formula
2. Halogens are replaced by H
3. Trivalent N is replaced by CH
4. The resulting hydrocarbon, C n H x , is compared with the saturated hydrocarbon,
C n H 2n+2 . Each double bond equivalent reduces the number of H atoms by 2:
double bond equivalents = ½ (2 n + 2 - x)
The above formula does not take into account additional double bond equivalents
that result from the higher valences of N that is not trivalent or S that is not divalent.
Ignoring higher valences, this formula predicts for example, for nitromethane one
double bond equivalent and for dimethyl sulfoxide and dimethyl sulfone none.
© The Author(s), under exclusive license to Springer-Verlag GmbH, DE,
part of Springer Nature 2020
E. Pretsch et al., Structure Determination of Organic Compounds,
https://doi.org/10.1007/978-3-662-62439-5_2
5