Disproportionation

Disproportionation is a redox reaction in which one chemical species is simultaneously oxidized and reduced, forming products with different oxidation states.

Oxidation state: A bookkeeping value assigned to an atom to track electron ownership in chemical compounds. Comparing oxidation states before and after reveals which products are oxidized and reduced.
Hydrogen peroxide disproportionation: The decomposition of hydrogen peroxide into water and oxygen, with peroxide acting as both oxidant and reductant. It is a familiar example in which oxygen forms products at two oxidation states.
Comproportionation: A redox reaction in which species of the same element at different oxidation states form a product at an intermediate state. It reverses the oxidation-state pattern: distinct starting states converge rather than one state splitting.
Bleach: A chemical product that removes color or disinfects, commonly through oxidizing agents such as hypochlorite. Disproportionation changes the composition and effectiveness of hypochlorite bleach over time.
Redox reaction: A chemical reaction involving electron transfer, expressed as coupled oxidation and reduction. Disproportionation is a distinctive case of oxidation and reduction within one reactant species.
Chlorine disproportionation: The reaction of chlorine with water or alkali to form chloride and oxychlorine products. Chlorine at oxidation state zero yields both reduced chloride and oxidized chlorine compounds.
Redox disproportionation: An alternate name for disproportionation, emphasizing its simultaneous oxidation and reduction. This is a synonym, not a contrasting reaction type.
Ozone decomposition: The conversion of ozone into oxygen, which can proceed through radical-chain pathways. Ozone can undergo a redox decomposition in which oxygen atoms reach different oxidation states in products.
Oxidation: A process in which a species loses electrons or increases its oxidation state. One fraction of the disproportionating species undergoes this change.
Frost diagram: A plot of Gibbs energy-related values for an element's oxidation states in a given medium. Its slopes and curvature can indicate whether an oxidation state tends to disproportionate.

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