Decomposition of hydrogen peroxide to free radicals

In the absence of initiators, alcohol oxidation is self-accelerating (see Sect. 2.1) due to the formation of peroxides, as in the case of hydrocarbon oxidation. The mechanism of free radical formation from peroxides was studied for 2-propanol [25] and cyclohexanol [32,56], The kinetics of hydrogen peroxide formation obeys the equation [25] 

The following reactions may be suggested for first-order decay of H202 to free radicals in alcohol 

Reactions (4) and (6) are consistent with the experimental value of E = 23 kcal mole 1, since E I—q I for an endothermic reaction. The fej value remains unchanged after dilution of cyclohexanol with both chlorobenzene and decane. Therefore the mechanism seems to be 

When [H202] 1 mole l 1, the bimolecular reaction becomes important [56] 

Ketones play an important part in the decomposition of peroxides to free radicals. With H202, they form hydroxyhydroperoxides (see Sect. 2.1) 

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