Radical Reactions Decomposition of Peroxide

In ionizing solvents, atoms and free radicals arc capable of being oxidized or reduced by charge transfer, and their modes of reaction can become very complex. One of the systems in which redox reactions involving atoms and radicals have been extensively studied is that between Fe and TT2O2. When equimolar, acidic solutions ( 0.01 M) of Fe and H2O2 are mixed together, there is a nearly quantitative reaction 

The modified Haber-Weiss mechanism which has been proposed to account for this and other observations is 

0—0 bond. Since Fe acts to reduce H2O2 to H2O, it can be seen that the combined action of the Fe+ -Fe couple is to catalyze the disproportionation of H2O2 to H2O + O2. A mechanism which seems in reasonable accord with those observations is 

This scheme has been simplified by ignoring the complexing of Fc + with OII , HO 2, or other negative ions which are known to be extensive. In addition it ignores the equilil)ria  

These acid-base equilibria will play an important role in determining the relative importance of the various steps, but as yet there is little clear-cut evidence concerning them. We have omitted the Fe + oxidation state because the evidence for it is quite tenuous. In addition the chain step of Weiss, HO2 + H2O2 H2O + OH + O2, is omitted as being structurally unreasonable.  

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