Ozonization products, oxidation

Table I. Ester By-products and Chain Degradation in Ozonization Product Oxidation...

Because of the formation of nitrogen oxides, a steady-state ozone concentration cannot be obtained instead, due to the buHdup of nitrogen oxides, an increase in residence time in the discharge results in a decrease in ozone concentration beyond the maximum value. Thus, there is an optimum residence time for maximum ozone production. 

Oxidation of phenols with chlorine dioxide or chlorine produces chlorinated aromatic intermediates before ring rupture. Oxidation of phenols with either chlorine dioxide or ozone produces oxidized aromatic compounds as intermediates which undergo ring rupture upon treatment with more oxidant and/or longer reaction times. In many cases, the same nonchlorinated, ringruptured aliphatic products are produced using ozone or chlorine dioxide. 

Certainly, photochemical air pollution is not merely a local problem. Indeed, spread of anthropogenic smog plumes away from urban centers results in regional scale oxidant problems, such as found in the NE United States and many southern States. Ozone production has also been connected with biomass burning in the tropics (79,80,81). Transport of large-scale tropospheric ozone plumes over large distances has been documented from satellite measurements of total atmospheric ozone (82,83,84), originally taken to study stratospheric ozone depletion. 

Cmtzen, P. J. (1971). Ozone production rates in an oxygen-hydrogen-nitrogen oxide atmosphere. /. Geophys. Res. 76,7311-7327. 

Spanggord RJ, CD Yao, T Mill (2000) Oxidation of aminodinitrotoluenes with ozone products and pathways. Environ Sci Technol 34 497-504. 

In addition to observations in Los Angeles, Blumenthal and White have reported measurements of a power-plant plume and an urban plume 35 and 46 km downwind from St. Louis, Nfissouri. Bgute 4-25 shows the evidence of extensive ozone buildup in the urban plume. Simultaneous measurements of scattering coefficient, 6>cat, trace the spread and dilution of suspended particulate material. It is interesting that in the urban plume, which spreads to 20 km in width, the ozone increases while the particulate matter decreases this suggests considerable photochemical production at an altitude of 750 m. Contrary to the statements of Davis and co-workers reported above, the power-plant plume causes a decrease, rather than an increase, in ozone. Nitric oxide in the plume reacts with the ozone as it mixes. This is clearly indicated by the distribution of particulate matter, which acts as a tracer. 

The oxidation of cysteine, as well as other amino acids, was studied by Mudd et a/. Individual amino acids in aqueous solution were exposed to ozone the reported order of susceptibility was cysteine, methionine, tryptophan, tyrosine, histidine, cystine, and phenylalanine. Other amino acids were not affected. This order is similar to that for the relative susceptibility of amino acrids to radiation and to lipid peroxides. Evaluation of the ozonization products revealed that cysteine was converted to cysteic acid, as well as cystine methionine to methionine sulfoxide tryptophan to a variety of pioducrts, including kynurenine and N-formylkynurenine tyrosine also to a variety of products, includiitg dihydroxyphenylalanine histidine to ammonia, proline, and other compounds and cystine in part to cysteic acid. In some cases, the rate and end products depended on the pH of the solution. 

Ozonization of phenol in water resulted in the formation of many oxidation products. The identified products in the order of degradation are catechol, hydroquinone, o-quinone, cis,ds-muconic acid, maleic (or fumaric) and oxalic acids (Eisenhauer, 1968). In addition, glyoxylic, formic, and acetic acids also were reported as ozonization products prior to oxidation to carbon dioxide (Kuo et al, 1977). Ozonation of an aqueous solution of phenol subjected to UV light (120-W low pressure mercury lamp) gave glyoxal, glyoxylic, oxalic, and formic acids as major products. Minor products included catechol, hydroquinone, muconic, fumaric, and maleic acids (Takahashi, 1990). Wet oxidation of phenol at 320 °C yielded formic and acetic acids (Randall and Knopp, 1980). 

Major oxidation products of propanolol and metoprolol formed during ozonation in aqueous solution were investigated by Benner et al. [102, 103]. In the case of propanolol, the main ozonation product is a ring-opened compound with two aldehyde moieties, which results from ozone attack to the naphthalene ring [103]. Formation of aldehyde moieties was also one of the main oxidation routes during metoprolol ozonation, together with hydroxylation [102]. 

Terpenoid DBPs were investigated by Joll et al. [124] and Qi et al. [125]. The main ozonation product of 2-methylisobomeol was camphor, which was further oxidized to formaldehyde, acetaldehyde, propanal, buntanal, glyoxal, and methyl glyoxal [125]. Chlorination of p-carotene, retinol, p-ionone, and geranyl acetate resulted in the formation of THMs [124]. 

The concentration of ozone taken up by the media containing linolenic acid is plotted against time after addition in Figure 8. The rate of ozone breakdown is constant (ozone uptake linear with time) for the first two min until about 0.12 ml ozone are absorbed and then the rate decreases sharply, reaching a steady-state rate of ozone uptake between 10-12 min. This first break in the curve corresponds to an ozone uptake of 0.12 ml + (24 moles/liter) = 0.005 millimoles (or 10 M). This is equivalent to 1 mole of linolenic acid added per mole ozone absorbed. Thiobarbituric acid reactant production is also plotted on the same axis. This compound (TBA reactant) probably arises by formation of a three-carbon fragment (malondialdehyde) from the ozone-induced oxidation of linolenic acid (23). The rate of TBA reactant formation is also linear for the first 2 min at which point the curve undergoes a less pronounced break. Malondialdehyde formation ceases immediately when the ozone is shut off (Scrub 1 on). An oxygen control sample produced no malondialdehyde. 

Stronger oxidizing agents such as hydrogen peroxide or ozone readily oxidize H2S forming sulfur and various other sulfur products. For example, HaOa reacts with HaS under neutral conditions forming sulfur and water ... 

Ozone is produced in the atmosphere when oxides of nitrogen react with volatile organic compounds in the presence of sunlight. Control of ozone production is achieved, therefore, by use of systems designed to reduce the emissions of and VOCs, such as those described in the sections on these two pollutants. 

Oxidation of Elaidic Acid Ozonization Products. Elaidic acid was ozonized in chloroform solution (5.0 grams in 100 ml.) at 0°C., and the solvent was removed by rotatory evaporation at room temperature. Aliquots were oxidized catalytically and noncatalytically as described above. 

Oxidation of Elaidic Acid Ozonization Products. Aliquots of the unseparated ozonization products from elaidic acid were autoxidized at 95 °C. uncatalyzed and in acetone over reduced platinum oxide as before. Total yields of acids and esters were determined by titration and were found to be 74.6 and 19.2%, respectively, in the catalyzed reaction with uptake of 63% of the theoretical volume of oxygen. Time required for uptake of half this volume was 4 hours at 21 °C. Uncatalyzed oxidation at 95°C. of the other fraction gave 27.4% yield of esters and 74.5% yield of acids, calculated on the assumption that one original olefinic linkage can produce one ester function or two acid functions. When elaidic acid was ozonized in methyl acetate and the catalyzed oxidation performed in the same solvent, acid yield was 80.8%, and ester yield was 7.3% with a half-uptake time of 5.6 hours and 88% of the theoretical quantity of... 

Crutzen, P. J., Ozone Production Rates in an Oxygen-Hydrogen-Nitrogen Oxide Atmosphere, J. Geophys. Res., 76, 7311-7327... 

Organic micropollutants are found in surface and ground waters, always in conjunction with more or less NOM, but at relatively low concentrations in the range of 0.1 pg L I to 100 pg L-1 (in water sources of sufficient quality for a water supply). Their degradation by ozone to oxidized metabolites or even to mineral products is a complex process, due to the influences of various water quality parameters (pH, inorganic and organic carbon etc.) on the two known major reaction pathways direct electrophilic ozone reaction and the oxidation via the nonselective, fast reacting OH-radicals. 

Optimization of mass transfer ) Should kLa be optimized by varying Qs (especially important in systems where mixing is exclusively provided by the gas flow rate, e. g. bubble columns, where 0G is the only variable parameter) No, in systems employing an EDOG (at a constant ozone production rate) two parameters will change at the same time and cause adverse effects on the oxidation-rate an increase in Qe normally increases kLa, but decreases cBo B 2.2.1.2... 

The 2,3-dihydrobenzo[6]selenophene (113) yields the oxide (114) on treatment with ozone. The oxide may be ring opened by treatment with sodium hydride and the product of the ring opening can be alkylated by reaction with benzyl bromide. Thermal rearrangement of the oxide yields a 15 85 mixture of compounds (115) and (116) (Scheme 15) (76JOC2503). 

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