H-Atom transfer to alkoxy radicals

5 H-Atom transfer to alkoxy radicals (a) General considerations 

Alkoxy radicals (RO) are important chain carriers in many oxidation reactions especially at higher temperatures [36,98]. They are formed in several reactions including self-reaction of tertiary R02- (Sect. 4.4) 

Much of the chemistry of RO- in the liquid phase is associated with the competition between H-atom transfer to give alcohol and /3-cleavage to give carbonyl and a new alkyl radical, viz. 

Addition of RO- to double bonds is not observed with most olefins despite the fact that the reaction is exothermic by about 20 kcal mole-1. The following sections review the thermochemistry of RO- reactions, 

H-Atom transfer to RO results in the formation of a 104 kcal mole-1 O—H bond with the result that all H-atom transfers from organic H-atom donors are exothermic to at least 6 kcal mole-1 and as much as 32 kcal mole-1 (see Table 4). For most alkanes and olefins, H-atom transfer reactions are exothermic by 9—16 kcal mole-1 and activation energies are low. 

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