Hydroperoxy! radical aqueous solution reactions

Pulse radiolysis experiments have shown that "OH radical adds preferentially at C5 of the uracil moiety, giving rise to the reducing 5-hydroxy-5,6-uracil-6-yl radical. Interestingly, the two cis diastereomers of 6-hydroperoxy-5-hydroxy-5,6-dihydrouridine, two of the expected final products of the latter radicals in aerated aqueous solutions, have been prepared by trifluoroacetic acid treatment of uridine (3, R = H, = ribose) in the presence of H202 (equation 14). The mechanism of the reaction that involves transient formation of an epoxide-type intermediate followed by nucleophilic attack by a perhy-droxyl group at C6 presents similarities with the substitution of thymine bromohydrin by... 

The use of a crosslinking mcxiomer to produce coherent coatings of otherwise soluble polymer is illustrated by the acrylamide//V,lV-methylendjisacrylamide tem. In the presence of ZnCl2> aqueous solutions of these monmners are found to be electropdymerized on metal cathodes. It hat been proposed that the initiation of polymerization here was by hydroperoxy radicals arising from a series of reactions beginning with the formatimi of from Zn and 02 In a recent reexamination of the kinetics of polymerization in this stem, eddence has been obtained... 

The effect of ionizing radiation (x or y rays) on tryptophan or on tryptophan-containing proteins in aerated aqueous solution is seemingly to bring about partial conversion of tryptophan to formylkynurenine (5, 206, 300). The oxidizing species are presumed to be hydroxy and hydroperoxy radicals. Oxindolylalanine does not seem to be an intermediate in the reaction. Suggested mechanisms (206, 300) propose 2-hydroxy-3-hydroperoxyindoline (86) as an intermediate. However, in the light of recent theories on tryptophan oxidation, which were discussed in other sections a modification of the above discussed mechanism can be also proposed which involves hydroperoxyindolenine as an intermediate. 

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