Telomerization is a reaction that produces a particular kind of oligomer with two distinct end groups. The oligomer is called a telomer. Some telomerizations proceed by radical pathways, many do not. A generic equation is:
where M is the monomer, and A and B are the end groups, and n is the degree of polymerization.
One example is the coupled dimerization and hydroesterification of buta-1,3-diene. This step produces a doubly unsaturated C9-ester:
The monomer in this reaction is butadiene, the degree of polymerization is 2, and the end groups are vinyl and the carboxy methyl (CO<sub>2</sub>CH<sub>3</sub>). This and several related reactions proceed with palladium catalysts. Many telomerizations are used in industrial chemistry.
According to the jargon in polymer chemistry, telomerization requires a telogen to react with at least one unsaturated taxogen molecule. Fluorotelomers are an example.