Disproportionation Definition in Chemistry

It's a chemical reaction that produces two or more dissimilar products

Scientist holding a flask with evaporating liquid

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Disproportionation is a chemical reaction, typically a redox reaction, where a molecule is transformed into two or more dissimilar products. In a redox reaction, the species is simultaneously oxidized and reduced to form at least two different products.

Disproportionation reactions follow the form:

  • 2A → A' + A"

where A, A', and A" are all different chemical species.
The reverse reaction of disproportionation is called comproportionation.


Hydrogen peroxide converting into water and oxygen is a disproportionation reaction.

  • 2 H2O2 → H2O + O2

Water dissociating into H3O+ and OH- is an example of a disproportionation reaction that is not a redox reaction.

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Helmenstine, Anne Marie, Ph.D. "Disproportionation Definition in Chemistry." ThoughtCo, Aug. 28, 2020, thoughtco.com/definition-of-disproportionation-605037. Helmenstine, Anne Marie, Ph.D. (2020, August 28). Disproportionation Definition in Chemistry. Retrieved from https://www.thoughtco.com/definition-of-disproportionation-605037 Helmenstine, Anne Marie, Ph.D. "Disproportionation Definition in Chemistry." ThoughtCo. https://www.thoughtco.com/definition-of-disproportionation-605037 (accessed January 25, 2021).