Disproportionation Definition

What Is Disproportionation in Chemistry?

In disproportionation, a chemical species is simultaneously oxidized and reduced to form two dissimilar products.
In disproportionation, a chemical species is simultaneously oxidized and reduced to form two dissimilar products. PM Images, Getty Images
by Anne Marie Helmenstine, Ph.D.
Updated March 08, 2017

Disproportionation Definition

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.

Examples: 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.