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Double Bond Equivalent Calculator

Table of contents

What is a double bond equivalent?How to use the double bond equivalent calculatorFormula to determine DBE, double bond equivalentHow to calculate the double bond equivalentDBE chartSignificance of DBEFAQs

Sometimes, we ourselves are unaware of the things we need in our lives, such as this double bond equivalent calculator. This calculator is a handy tool that helps you to determine the DBE value for organic molecules which, in turn, enables you to determine the presence or absence of double or triple bonds or rings in the structure of an organic molecule.

In this article, we will also be talking about the double bond equivalent equation on which the DBE formula is based, along with a DBE chart that shows some common double bond equivalent values with their interpretation of the type of bonds.

What is a double bond equivalent?

The double bond equivalent, DBE, represents the number of pi bonds or rings in an organic molecule. It gives information on the unsaturated sites in a molecule.

Some other names for DBE are:

  • Degree of unsaturation (DoU);
  • Unsaturation index (UI); or
  • Index of hydrogen deficiency (IHD).

The value also represents the number of hydrogen atoms to be added to the organic molecule to remove the unsaturation, convert the pi bonds to single bonds, and convert them to acyclic structures in the case of rings. This is significant in studying the reactivity of molecules, with the presence of pi bonds and rings rather than the impact on it.

Did we tell you that we have a degree of unsaturation calculator? You are sure to like it.

How to use the double bond equivalent calculator

Double bond equivalent calculator. Saying the name might be a mouthful, but using the tool is quite the opposite—simple and straightforward inputs with instant results.

Let's take a look at the steps.

  1. Enter the number of carbon atoms in your molecule.
  2. Input the number of hydrogen atoms.
  3. Next, enter the number of oxygen atoms your molecule has. But remember, the presence or absence of oxygen does not impact the DBE value.
  4. Next comes the number of halogen atoms, i.e., F, Cl, Br, I, At.
  5. Lastly, enter the number of nitrogen atoms.
  6. The DBE value is displayed instantly.
  7. If the molecule under question doesn't have any of the above atoms, you may enter zero.

Let's consider an example. Say you want to know the DBE value of arginine, an amino acid responsible for building protein in the body. The formula of arginine is C6H14N4O2. Enter the relevant values, and for halogen, enter 0. The calculator will tell you that the DBE value for arginine is 2.

You might enjoy checking out our bond order calculator.

Formula to determine DBE, double bond equivalent

The double bond equivalent equation uses the number of carbon, hydrogen, halogens, and nitrogen atoms in an organic molecule. Remember that the presence or absence of oxygen in an organic molecule does not impact the DBE value.

The DBE formula is:

DBE=C+1H2X2+N2{\rm DBE} = C + 1 - \frac{H}{2} - \frac{X}{2} + \frac{N}{2}

where:

  • DBE\text{DBE} — Double bond equivalent;
  • CC — Number of carbon atoms;
  • HH — Number of hydrogen atoms;
  • XX — Number of halogen atoms; and
  • NN — Number of nitrogen atoms.

How to calculate the double bond equivalent

Now that we know the DBE formula, we can easily calculate the double bond equivalent for any organic compound. This can come in handy for the next class quiz or for situations where you can't take assistance from an online tool.

Let's walk through with an example. Say our organic molecule under question is our favorite, glucose, C6H12O6.

  1. Now, substitute the values in the formula, and since there are no halogens or nitrogens in the molecule, they will be taken as zero.

    DBE=C+1H2X2+N2\text{DBE} = C + 1 - \frac{H}{2} - \frac{X}{2} + \frac{N}{2}

    DBE=6+112202+02\text{DBE} = 6 + 1 - \frac{12}{2} - \frac{0}{2} + \frac{0}{2}

  2. Now, solve all the ones in fractions.

    DBE=6+160+0\text{DBE} = 6 + 1 - 6 - 0 + 0

  3. Simplify the equation.

    DBE=1\text{DBE} = 1

  4. And you have the DBE value for glucose.

The next time someone asks you, how to calculate the double bond equivalent of glucose, or any other organic molecule, you can do the math for them.

DBE chart

The DBE chart shows double bond equivalent values ranging from 0 to 10 and the corresponding number of double bonds, triple bonds, and rings.

DBE

Double bonds

Triple bonds

Rings

0

0

0

0

1

1

0

0

2

0

1

0

3

1

0

1

4

0

1

1

5

1

0

2

6

0

1

2

7

1

0

3

8

0

1

3

9

1

0

4

10

0

1

4

Although there are many variations of each DBE value, this chart shows only one possible combination of each value.

Significance of DBE

Calculating the double bond equivalent is significant to get an instant estimation of the level of unsaturation in a molecular structure. Although it does not identify a molecule's structure, it can estimate the number of pi bonds and rings.

Degree of unsaturation: DBE is another name for the degree of unsaturation. However, the DBE value indicates levels of unsaturation in a molecule. The higher the DBE value, the greater the level of unsaturation.

Structure elucidation: The double bond equivalent value can guide chemists in proposing reasonable structures for complex organic molecules. When working with spectroscopic data, it can be especially useful for narrowing down structural possibilities.

Prediction of unsaturated sites: The reactivity of molecules is affected by the presence of double and triple bonds. The DBE value helps in predicting these unsaturated sites.

In summary, the significance of DBE in organic chemistry is undeniable because it provides a quick method to assess a molecule's unsaturation, assist in determining a molecule's formula, and guide structural elucidation.

We suggest trying our molecular weight calculator. It is sure to come in handy to determine the atomic or molecular weight.

FAQs

What is the DBE value for lysine?

Lysine, an alpha-amino acid with the molecular formula C6H14N2O2 has a double bond equivalence (DBE) value of 1.

Let's calculate the value using the DBE formula to determine the DBE for lysine.

DBE = C + 1 − H/2 − X/2 + N/2

Substitute the values:

DBE = 6 + 1 − 14/2 − 0/2 + 2/2

DBE = 6 + 1 − 7 − 0 + 1

DBE = 7 − 7 + 1

DBE = 1

You can verify the result using our DBE calculator.

How can I calculate the double bond equivalent?

The double bond equivalence value is easy to calculate. Follow the steps below, and you will have your answer in no time.

  1. Add 1 to the number of carbon atoms.
  2. Subtract the number of hydrogen atoms divided by 2 from the above result.
  3. Subtract the number of halogen atoms divided by 2 from the above result.
  4. Add the number of nitrogen atoms divided by 2 to the above result.
  5. The result is the DBE value.

What does a DBE value of 3 mean?

The double bond equivalent value of 3 has various combinations of bonds and rings, as shown in the following table:

Double bond

Triple bond

Rings

0

0

3

1

0

2

2

0

1

1

1

0

3

0

0

0

1

1

What is the double bond equivalent of C10H14Br2?

The double bond equivalent of 1,3-Dibromoadamantane C10H14Br2 is 3.

You can easily determine it using the double bond equivalent equation.

DBE = C + 1 − H/2 − X/2 + N/2

DBE = 10 + 1 − 14/2 − 2/2 + 0/2

DBE = 11 − 7 - 1 + 0

DBE = 3

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Oxygen
The presence or absence of oxygen in the organic molecule has no impact on the DBE value.

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