Radical Addition to Alkenes, Dienes, and Polyenes

Almost all of the reactions in Table 6.3 require the addition of an initiator or the use of light (usually in the UV region of the spectrum) of sufficient energy to induce homolysis of the most fragile bond in the system. Thermal homolysis, when peroxides (RO-OR) are used, is possible only because of the lability of the oxygen-oxygen bond (see Table 1.1, Chapter 1). 

TABLE 63. Representative Reactions between Free Radicals and Alkenes 

The examples in the table are an incomplete (but representative) set of free radical reactions with alkenes. 

In Table 6.4 there is a representative set of dienes that have been polymerized, either alone or (copolymerized) with another diene or some suitable alkene to produce elastomers of commercial value. In many cases the details of the process(es) by which the polymerization has occurred remain obscure and/or unreported. 

2-methyl-l,3-butadiene (isoprene) 3H2OCH2 -H 2H2OCHCH3 ethene (ethylene) propene (propylene) 

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