1. Any chemical reaction of the type D01799-0.png, where A, A' and A'' are different chemical species. For example:
    The reverse of disproportionation is called @[email protected] A special case of disproportionation (or 'dismutation') is 'radical disproportionation', exemplified by:
    Reactions of the more general type:
    are also loosely described as radical disproportionations.
    PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1107 [Terms] [Paper]
  2. A @[email protected] or @[email protected] in which species with the same @[email protected] combine to yield one of higher @[email protected] and one of lower @[email protected] Example: D01799-4.png The term also applies to an internal @[email protected] process as occurs, for example, among the iron atoms of CaFeO3, where D01799-5.png, at Fe subarrays on lowering the temperature.
    PAC, 1994, 66, 577. (Definitions of terms relating to phase transitions of the solid state (IUPAC Recommendations 1994)) on page 581 [Terms] [Paper]