Disproportionating

Disproportionating refers to a type of chemical reaction where a single element in a compound is simultaneously oxidized and reduced. This means that atoms of the same element start with the same oxidation state, and then some of those atoms end up with a higher oxidation state (oxidation) while others end up with a lower oxidation state (reduction). This process occurs in a single reaction.

A common example of disproportionation is the reaction of hydrogen peroxide. In the presence of a catalyst, hydrogen peroxide can decompose into water and oxygen. Here, the oxidation state of oxygen in hydrogen peroxide is -1. In water, the oxidation state of oxygen is -2 (reduced), and in oxygen gas, the oxidation state is 0 (oxidized). Thus, the oxygen atoms in hydrogen peroxide are simultaneously reduced and oxidized.

Another classic example is the reaction of halogens like chlorine in a basic solution. Chlorine (oxidation state 0) can react to form chloride ions (oxidation state -1, reduced) and hypochlorite ions (oxidation state +1, oxidized). This same principle applies to various other elements and compounds under specific conditions, often involving changes in pH or the presence of catalysts. The key characteristic is the transformation of a single element into two different species with different oxidation states within the same reaction vessel.