the corresponding ester. In the Kornblum–DeLaMare rearrangement, a peroxide is converted to a ketone and an alcohol. The disproportionation of hydrogen peroxide into water and oxygen catalysed by either potassium iodide or the enzyme catalase: 2 H2O2 -> 2 H2O + O2 In the Boudouard reaction, carbon monoxide disproportionates to carbon and carbon dioxide. The reaction is for example used in the HiPco method for producing carbon nanotubes, high-pressure carbon monoxide disproportionates when catalysed on the surface of an iron particle: 2 CO -> C + CO2 Nitrogen has oxidation state +4 in nitrogen dioxide, but when this compound reacts with water, it forms both nitric acid and nitrous acid, where nitrogen has oxidation states +5 and +3 respectively: 2NO2 + H2O -> HNO3 + HNO2 Dithionite undergoes acid hydrolysis to thiosulfate and bisulfite: 2 {S2O4^{2-}} + H2O -> {S2O3^{2-}} + 2 HSO3- Dithionite also undergoes alkaline hydrolysis to sulfite and sulfide: 3 Na2S2O4 + 6 NaOH -> 5 Na2SO3 + Na2S + 3 H2O Dithionate is prepared on a larger scale by oxidizing a cooled aqueous solution of sulfur dioxide with manganese dioxide: 2 MnO2 + 3 SO2 -> MnS2O6 + MnSO4 Polymer chemistry In free-radical chain-growth polymerization, chain termination can occur by a disproportionation step in which a hydrogen atom is transferred from one growing chain molecule to another which produces two dead (non-growing) chains. -------CH2–C°HX + -------CH2–C°HX → -------CH=CHX + -------CH2–CH2X Biochemistry In 1937, Hans Adolf Krebs, who discovered the citric acid cycle bearing his name, confirmed the anaerobic dismutation of pyruvic acid into lactic acid, acetic acid and CO2 by certain bacteria according to the global reaction: 2 pyruvic acid + H2O → lactic acid + acetic acid + CO2 The dismutation of pyruvic acid in other small organic molecules (ethanol + CO2, or lactate and acetate, depending on the environmental conditions) is also an important step in fermentation reactions. Fermentation reactions can also be considered as disproportionation or dismutation biochemical reactions. Indeed, the donor and acceptor of electrons in the redox reactions supplying the chemical energy in these complex biochemical systems are the same organic molecules simultaneously acting as reductant or oxidant. Another example of biochemical dismutation reaction is the disproportionation of acetaldehyde into ethanol and acetic acid. While in respiration electrons are transferred from substrate (electron donor) to an electron acceptor, in fermentation part of the substrate molecule itself accepts the electrons. Fermentation is