New Mechanistic Aspects of the Fenton Reaction

The kinetics of the Fenton reaction was studied in detail. A second reaction step in the presence of excess H2O2 is attributed to formation of the complex Fe-III(-O2H)(aq). Therefore, the reaction of Fe(H2O)(6)(2+) with Fe-III(-O2H)(aq) in the presence of Fe-II to form Fe-aq(III) (k = (7.7 +/- 1.5) x 10(5) M-1 S-1) may contribute to the overall Fenton reaction, and could account for some of the debate in the literature concerning its detailed mechanism. If this is correct for LFeIII(-O2H)(aq) also, then it might be of significant biological importance. The activation parameters Delta H double dagger, Delta S double dagger, and Delta V double dagger for the Fenton reaction were measured under various experimental conditions, and are used in the mechanistic interpretation.