A @C01033@ of two or more reacting @M03986@ entities, resulting in a single reaction product containing all atoms of all components, with formation of two chemical bonds and a net reduction in bond multiplicity in at least one of the reactants. The reverse process is called an @E02038@ reaction. The addition may occur at only one site (@A00001@, 1/1/addition), at two adjacent sites (1/2/addition) or at two non-adjacent sites (1/3/- or 1/4/addition, etc.). For example:
A00133-2.pngIf the @R05190@ or the source of the addends of an addition are not specified, then it is called an addition @T06446@.