Double Bond Equivalent

Calculate molecular double-bond equivalents from C/H/N/halogen counts.

Description

Double-bond equivalent summarizes hydrogen deficiency from elemental counts under a simple valence model.

Double-bond equivalent summarizes hydrogen deficiency from elemental counts under a simple valence model. An integer nonnegative result is only a preliminary formula screen.^[1]

Calculate molecular double-bond equivalents from C/H/N/halogen counts.

When to use Double Bond Equivalent

Use this tool to calculate molecular double-bond equivalents from C/H/N/halogen counts.

Prepare the measured profile, formula counts, upstream model outputs or caller-defined reference criteria requested. Keep paired entries aligned and units, sample basis and preprocessing consistent.

How to use Double Bond Equivalent and understand its results

Prepare the measured profile, formula counts, upstream model outputs or caller-defined reference criteria requested. Keep paired entries aligned and units, sample basis and preprocessing consistent.
Enter carbon, hydrogen, nitrogen, halogens using the field table and calculation rules, then run the tool.
Read dbe, formulaValid. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
carbon	Carbon	number	Required
hydrogen	Hydrogen	number	Required
nitrogen	Nitrogen	number	Required
halogens	Halogens	number	Required

Enter nonnegative safe integer carbon, hydrogen, nitrogen and halogen counts. Return DBE and a flag requiring it to be both integral and nonnegative.

DBE=1+C−H/2+N/2−halogens/2

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
dbe	Dbe	number
formulaValid	Formula valid	boolean

json

{
  "input": {
    "carbon": 6,
    "hydrogen": 6,
    "nitrogen": 0,
    "halogens": 0
  },
  "output": {
    "dbe": 4,
    "formulaValid": true
  }
}

Limitations and assumptions

Oxygen and sulfur are absent from this expression. Ion type, valence exceptions and structural feasibility are not checked.

Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors. A successfully returned false flag is an evaluated outcome; its meaning is explained above.

Alternative or Complementary methods

Use Monoisotopic Formula Mass: Sum neutral monoisotopic mass from C/H/N/O/S/P atomic compositions. For a complementary task, use Nitrogen Rule Parity: Check nitrogen-rule parity for an even-electron molecular ion.

References

Double Bond Equivalent — tool.io

Similar or alternative tools

Monoisotopic Formula Mass
Sum neutral monoisotopic mass from C/H/N/O/S/P atomic compositions.
Nitrogen Rule Parity
Check nitrogen-rule parity for an even-electron molecular ion.