As a fast reaction

In fact, this organic Fenton reaction is energetically more favourable than that observed with hydrogen peroxide, and it can be visualized as a fast reaction for primary and secondary hydroperoxides. The reverse one-electron oxidative cleavage of hydroperoxides to peroxyl radicals ROO may also be envisaged [24] ... 

The slow reaction regime is characterized by the fact that the amount of the aromatic reactant that reacts in the film at the interface between phases is negligible compared to the amount that diffuses into the acid phase. Either the intrinsic kinetics or the rate of bulk-diffusion of the aromatic reactant may be the rate controlling step. The second type of reaction system is designated as a fast reaction system, and benzene would react in... 

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