Hydroxyl radical electrophilic addition

Specifically, hydroxyl radicals can oxidize organics by hydroxylation, hydrogen abstraction, electrophilic addition, and electron transfer, depending upon the nature of organic compounds. 

Electrophilic addition of hydroxyl radicals to organic n systems will lead to organic radicals, as shown in the following equation ... 

When hydrogen abstraction or electrophilic addition reactions may be inhibited by multiple halogen substitutions or steric hindrance, a hydroxyl radical can be reduced to a hydroxide anion by an organic substrate shown in Equation (7.28) ... 

The oxidation of organic compounds by hydroxyl radicals follows the same reaction through hydrogen abstraction or electrophilic addition, depending upon the nature of the organic compound ... 

Reactivities of a variety of alcohols, ethers, and amides toward hydroxy radicals derived from Fenton s reagent have been compared with those obtained from radiation chemistry in the absence of iron species.728 b Reactivities of different C—H bonds indicate that hydroxyl radical is a strongly electrophilic radical so that electron supply is more important than C—H bond strength in determining its reactivity. Fenton s reagent thus serves as a useful means for studying the one-electron oxidation and reduction of the resulting carbon-centered radicals with iron(II, III) species.73a,b Furthermore, in these systems the addition of copper(II) complexes that can intercept free radicals effectively often leads to enhanced yields of oxidation products.72 73... 

The hydroxyl radical is an electrophilic particle. The rate of its addition to propene is six times higher than to ethylene [131]. Also, hydroperoxyl is electrophilic. The possibilities of its reactions are already very diverse [132]. This makes more difficult the evaluation of addition. 

The reduction potential [22] of the hydroxyl radical is E° = 1.9V versus NHE it is therefore an extremely strong electrophile that rapidly and unselectively reacts with DNA mostly via the addition to double bonds of the nucleobases, and by the abstraction of hydrogen atoms from either the 2-deoxyribose moieties or the methyl group of thymine. 

Aliphatic nitro compounds are characterized by another interesting and mechanistically important property. Based on tautomeric and protolytic equilibria the stable form of nitromethane in basic solution is that of a double bonded ac/-nitromethane anion, CH2=N02 , which becomes ready target for electrophilic radical additions. An example, studied by pulse radiolysis, is its reaction with hydroxyl radicals as formulated in eq. 3."... 

The (indirect) photodegradation - reaction with reactive species formed by photochemical processes - has been recognized as the major transformation pathway for chemicals in the troposphere. The electrophilic addition of tropospheric radicals constitutes the principal degradation pathway. The relevant reactive species are hydroxyl radicals (OH ) and ozone (O3) during day time and N03 radicals at night. The hydroxyl radicals result from reactions of oxygen atoms with water vapour, photolysis of HNO2 and reactions of HO2 (a... 

A new structure-activity relationship, Xjj =yS+l, where y is a negative constant, S is the total steric effect, and 4 is the total inductive effect, correlated strongly with available measurements of ozonolysis. New rate coefficients were measured for ozonolysis of a number of unsaturated heteroatomic compounds and it has been emphasized that the inductive effect rather than the steric effect is important in predicting their reactivity %, the inductive effect index, was compared with the Taft a constant and rates of reaction of hydroxyl radical with a given species it correlated strongly in both cases (which should be unaffected by steric factors) suggesting a universal response by olefinic species towards electrophilic addition. ... 

---