Oxidation by ozone

Unpiotonated hydioxylamine is oxidized rapidly by ozone, / = 2.1 X 10 (39). The reaction of ozone with the lower oxides of nitrogen (NO and NO2) is also rapid and quantitative the end product is nitrogen pentoxide, which is also a catalyst for the decomposition of ozone (45). Nitrous oxide, however, reacts slowly (k < 10 ) (39). Nitrogen-containing anions, eg, nitrite and cyanide, also ate oxidized by ozone (39). Nitrite is oxidized to nitrate (fc = 3.7 X 10 and cyanide is oxidized rapidly to cyanate (fc = 2.6 X 10 (46) and 10 -10 (39)). Cyanate, however, is oxidized slowly. 

Sulfur Compounds. Aqueous sulfide and H2S, an odiferous compound in some waters, are oxidized rapidly (initially to sulfite and sulfurous acid) the rate constants ate 3x10 and 3 X 10 , respectively. Thiocyanate is oxidized by ozone to cyanide and sulfate via the intermediate formation of sulfite (47). 

Metals and Metallic Ions. Under appropriate conditions, ozone oxidizes most metals with the exception of gold and the platinum group. When oxidized by ozone, heavy metal ions, such as Fe and Mn , result in the precipitation of insoluble hydroxides or oxides upon hydrolysis (48—50). Excess ozone oxidizes ferric hydroxide in alkaline media to ferrate, and Mn02 to MnO. ... 

Mercaptans, thioethers, and disulfides are readily oxidized by ozone. 

Iron and Manganese Removal. Soluble ferrous and manganous ions are oxidized by ozone (typicaUy 2.5 ppm) to less soluble higher... 

Many of the metal chlorites are not particularly stable and will explode or detonate when stmck or heated. These include the salts of Hg", Tl", Pb ", Cu", and Ag". Extremely fast decomposition with high heat evolution has been noted for barium chlorite [14674-74-9] Ba(Cl02)2, at 190°C, silver chlorite [7783-91-7] AgC102, at 120°C, and lead chlorite [13453-57-17, at 103°C (109). Sodium chlorite can be oxidized by ozone to form chlorine dioxide under acidic conditions (110) ... 

CIS- And trans-1,2-difluoroethylene are oxidized by ozone stereoselectively to a mixture of the corresponding epoxides and ozonides with formyl fluoride The composition of the mixture depends on the solvent used [25] (equation 16)... 

In addition to reactions with HO, tropospheric organic compounds may be oxidized by ozone (via ozonation of non-aromatic carbon/carbon double bonds, Atkinson 1990) and in some cases by reaction with nitrate radical, described below. Table I gives representative trace-gas removal rates for these three processes. In spite of these competing reactions, HO largely serves as... 

The surface oxidation products are mainly carbonyl and/or carboxyl groups, with lower level of hydroperoxide groups. The mechanisms of oxidation by ozone and atomic oxygen have been proposed. 

In air, in the absence of additives, NO removal takes place by oxidation [56-58], Wu et al. [56] observed that the concentration of ozone generated in the corona discharge in the presence of NO is significantly smaller as compared to the ozone formed in air without NO under the same conditions. Thus, they concluded that NO oxidation by ozone and atomic oxygen is an important reaction path for the NO conversion. 

LG Galimova. Mechanism of Cyclohexane Oxidation by Ozone, Thesis Dissertation, BSU, Ufa, 1975 pp 3-25 [in Russian]. 

Both models apply the same chemical scheme of mercury transformations. It is assumed that mercury occurs in the atmosphere in two gaseous forms—gaseous elemental HgO, gaseous oxidized Hg(II) particulate oxidized Hgpart, and four aqueous forms—elemental dissolved HgO dis, mercury ion Hg2+, sulphite complex Hg(S03)2, and aggregate chloride complexes HgnClm. Physical and chemical transformations include dissolution of HgO in cloud droplets, gas-phase and aqueous-phase oxidation by ozone and chlorine, aqueous-phase formation of chloride complexes, reactions of Hg2+ reduction through the decomposition of sulphite complex, and adsorption by soot particles in droplet water. 

Chemical/Physical. Oxidation by ozone to fluorenone has been reported (Nikolaou, 1984). Chlorination of fluorene in polluted humus poor lake water gave a chlorinated derivative tentatively identified as 2-chlorofluorene (Johnsen et al., 1989). This compound was also identified as a chlorination product of fluorene at low pH (<4) (Oyler et al, 1983). It was suggested that the chlorination of fluorene in tap water accounted for the presence of chlorofluorene (Shiraishi et al., 1985). 

Photolysis Abiotic oxidation occurring in surface water is often light mediated. Both direct oxidative photolysis and indirect light-induced oxidation via a photolytic mechanism may introduce reactive species able to enhance the redox process in the system. These species include singlet molecular O, hydroxyl-free radicals, super oxide radical anions, and hydrogen peroxide. In addition to the photolytic pathway, induced oxidation may include direct oxidation by ozone (Spencer et al. 1980) autooxidation enhanced by metals (Stone and Morgan 1987) and peroxides (Mill et al. 1980). 

The second class of biochemicals which is significantly oxidized by ozone is sulfhydryls. The di-sulfhydryl compound, dithiothreitol (DTT), readily loses 2 H to form a cyclic disulfide (26). This compound is used to study how ozone reacts with a sulfhydryl system and whether these reactions are stoichiometric (Fig. 11). 

Smog formation in the atmosphere is caused by such reaction. Nitrogen dioxide is rapidly oxidized by ozone to form nitrogen pentoxide ... 

This route to the a-nitroso derivatives of the 7r-deficient heterocycles has permitted an exploration of their chemistry. They are extremely reactive and condense readily with 1,3-dienes to give 3,6-dihydro-l,2-oxazines (e.g. 99), and with aromatic amines in the presence of acid to give azo compounds (Scheme 86). This latter reaction is particularly useful in view of the instability of the corresponding 2-pyridinediazonium salts referred to above, which limits conventional access. The a-nitroso heterocycles are oxidized by ozone or sodium hypochlorite to the a-nitro compounds (Scheme 86) (82JOC553). 

Kotzick, R., U. Panne, and R. Niessner, Changes in Condensation Properties of Ultrafine Carbon Particles Subjected to Oxidation by Ozone, J. Aerosol Sci, 28, 725-735 (1997). 

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