Reactions involving Halogen Oxide Radicals

Schmidt KH, Flan P, Bartels DM (1995) Radiolytic yields of the hydrated electron from transient conductivity improved calculation of the hydrated electron diffusion coefficient and analysis of some diffusion-limited (e )aq reaction rates. J Phys Chem 99 10530-10539 Schoneich C, Aced A, Asmus K-D (1991) Halogenated peroxyl radicals as two-electron-transfer agents. Oxidation of organic sulfides to sulfoxides. J Am Chem Soc 113 375-376 Schuchmann Fl-P, von Sonntag C (1981) Photolysis at 185 nm of dimethyl ether in aqueous solution Involvement of the hydroxymethyl radical. J Photochem 16 289-295 Schuchmann Fl-P, von Sonntag C (1984) Methylperoxyl radicals a study ofthey-radiolysis of methane in oxygenated aqueous solutions. Z Naturforsch 39b 217-221 Schuchmann Fl-P, von Sonntag C (1997) Heteroatom peroxyl radicals. In Alfassi ZB (ed) Peroxyl radicals. Wiley, Chichester, pp 439-455... 

Hydrogen peroxide is also the oxidant in the halogenations of alkanes under Gif conditions. In these systems, developed by Barton and his coworkers312, alkanes are selectively transformed into alkyl chlorides or bromides by polyhaloalkanes and H202 in the presence of FeCypicolinic acid catalyst in pyridine/acetic acid solvent313-315. It has clearly been established that the reaction mechanism does not involve a free-radical intermediate. 

Among the main O3 destmction paths (cycles) involving these radicals are also reactions of the halogen oxides XO with HO2 (cycle I) ... 

Methane forms explosive mixtures with air the LEL and UEL values are 5.5% and 14% by volume of air, respectively. The explosion is loudest at 10% volume concentration. The combustion of methane in air forming CO2 involves chain reactions, propagated by free radicals, CH3-, HO-, H-, and O- (Meyer 1989). Being a saturated molecule, the reactivity of methane toward most substances is very low. However, under catalytic conditions, violent reactions have been reported with halogens and certain fluorides of nonmetals. This includes reactions with chlorine at room temperature over yellow mercuric oxide, bromine pentafluoride, oxygen difluoride in the presence of a spark (MeUor 1946, Suppl. 1956), and nitrogen trifluoride (Lawless and Smith 1968). 

Addition reactions, electron transfer reactions, and reactions involving the opening of the fullerene cage (chemical surgery) have been thoroughly studied on fullerenes. Other reactions such as nucleophilic additions, cycloaddition reactions, free-radical additions, halogenations, hydroxylation, redox reactions, and metal transition complexations have been reported for Cgo as well. Furthermore, fullerenes are easily reduced by electron-rich chemical reagents as well as electrochemically. Their oxidation, however, is considerably more difficult to achieve [17]. Thus, electrochemical measurements showed the formation from the monoanion to the hexaanion [18]. 

Sections Free radical halogenation and oxidation involve reactions at the benzylic 11 12-11 13 carbon See Table 112... 

A chain mechanism is proposed for this reaction. The first step is oxidation of a carboxylate ion coordinated to Pb(IV), with formation of alkyl radical, carbon dioxide, and Pb(III). The alkyl radical then abstracts halogen from a Pb(IV) complex, generating a Pb(IIl) species that decomposes to Pb(II) and an alkyl radical. This alkyl radical can continue the chain process. The step involving abstraction of halide from a complex with a change in metal-ion oxidation state is a ligand-transfer type reaction. 

---