The key difference between dismutation and disproportionation is that dismutation is the equivalent term to name disproportionation in the biological systems whereas disproportionation is a redox reaction in which both oxidation and reduction reactions take place in the same reactant.

A redox reaction is a form of chemical reaction in which the oxidation states of atoms in molecules change during the progression of the reaction. Furthermore, this type of reactions has two parallel half reactions; oxidation reaction and reduction reaction.

CONTENTS

1. Overview and Key Difference
2. What is Dismutation
3. What is Disproportionation
4. Side by Side Comparison – Dismutation vs Disproportionation in Tabular Form
5. Summary

What is Dismutation?

Dismutation is the disproportionation that takes place in biological systems. Therefore, both dismutation and disproportionation are equal in their processes, only the application of the term is different.

Figure 01: The Mechanism of Dismutation (dismutation of superoxide free radical)

For example, in citric acid cycle of some bacteria, pyruvic acid converts into lactic acid, acetic acid, and carbon dioxide. This reaction is also known as anaerobic dismutation.

What is Disproportionation?

Disproportionation is a redox reaction in which both the oxidation and reduction reactions take place in the same reactant. In a redox reaction, the oxidation states of atoms in reactants change. Therefore, in disproportionation, the oxidation state of an atom of a reactant molecule increases while the oxidation state of an atom of the same reactant molecule decreases at the same time. And also for the disproportionation to occur, there should be a chemical species with an intermediate oxidation state.

2A      →      A+    +     A–

Examples

Some common examples for disproportionation are given below.

• Disproportionation of mercurous chloride into mercury and mercuric chloride.

Hg2Cl2   →      Hg   +   HgCl2

• Disproportionation of phosphorous acid into phosphoric acid and phosphine.

4H3PO3→   3H3PO4    +    PH3

• Disproportionation of bicarbonate anion.

2HCO3–→       CO32-   +     H2CO3

• Disproportionation of nitrogen dioxide into nitric acid and nitrous acid when reacted with water.

2NO2   +    H2O     →HNO3     +     HNO2

What is the Difference Between Dismutation and Disproportionation?

Summary – Dismutation vs Disproportionation

The terms dismutation and disproportionation describes the same chemical process. However, only the application of the term is different. The difference between dismutation and disproportionation is that dismutation is the term to name disproportionation that occurs in biological systems whereas disproportionation is a redox reaction in which the oxidation and reduction reactions take place in the same reactant.

Reference:

1. “Dismutation Medical Definition.” Merriam-Webster, Merriam-Webster. Available here
2. “Dismutation.” Dismutation – Wiktionary. Available here 
3. “Disproportionation.” Wikipedia, Wikimedia Foundation, 4 Apr. 2018. Available here 
4. “Redox.” Wikipedia, Wikimedia Foundation, 14 Apr. 2018. Available here  

Image Courtesy:

1.’Reaction mechanism of dismutation’By Tinisanelement – Own work, (CC BY-SA 4.0) via Commons Wikimedia  

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