User:B Saward/initiation (chemistry)

In chemistry, initiation is a chemical reaction that triggers one or more secondary reactions. Often the initiation reaction generates a reactive intermediate from a stable molecule which is then involved in secondary reactions. In polymerisation, initiation is followed by a chain reaction and termination.

Classes of Initiators
Different classes of compounds may be broken down under photolytic or thermolytic conditions to produce radical species:

Peroxides
The peroxides are common initiators due to the weak oxygen-oxygen bond that can be homolytically cleaved by heat or UV-light. An example is benzoyl peroxide which undergoes thermolysis above 160oC, to liberate carbon dioxide and phenyl radicals.



Halogens
Halogens such as bromine will decompose