Sulfur atmospheric reactions

Reduced sulfur fuel, 18 667 Reducing agents, 9 687, 688-689 Reducing atmospheres, reaction of photoholes with, 19 84-85 Reducing bleaches, 4 63-64 bleaching mechanism, 4 47 Reducing chemistry, in water treatment, 23 222-226... 

The sulfate and nitrate content of atmospheric particles comes primarily from the conversion of sulfur dioxide and nitrogen dioxide. Photochemi-cally initiated atmospheric reactions and transient free radicals are... 

Thus, the eventual products of the two pathways (la) and (lb) by which OH reacts with DMS under atmospheric conditions have not yet been fully established. However, circumstantial evidence, namely the 70% yield of SO2 in the study of Barnes et al. (21) being roughly equal to the branching ratio for the H-atom abstraction (reaction (la)) at 298 K determined by Hynes et al. (12), indicates that S02 is a major product of the abstraction reaction and that DMSO, DMSO and MSA probably result from the primary addition of OH to the sulfur atom (reaction (lb)). 

Another of Ariya s research interests is sulfur, S. She and her students are studying its atmospheric reactions with ozone and hydrogen peroxide, H2O2. Through field studies, laboratory experiments, and modelling, they are trying to determine the impacts of such reactions. 

These reactions may be important for several reasons. It may be possible to use the chemiluminescent reaction of ozone with organic sulfides to monitor the low concentrations of sulfur compounds in urban atmospheres. Also, excited species are being formed, and these reactive intermediates may be important in high altitude atmospheric reactions. Finally, identifying these emitting species should give information about the mechanisms of gas phase ozone reactions. Current progress on these reactions by the authors is reviewed here. 

Boyle, J.M., 1976. Atmospheric Reactions of Sulfur Dioxide and Monoterpenes. M.Sc. Thesis, The University of Calgary, Calgary, Canada, 97 pp. 

Possible atmospheric reaction products are oxy-, hydroxy-, nitro- and hydroxynitro-PAH derivatives (Baek et al. 1991). Photochemical oxidation of a number of PAHs has been reported with the formation of nitrated PAHs, quinones, phenols, and dihydrodiols (Holloway et al. 1987 Kamens et al. 1986). Some of these breakdown products are mutagenic (Gibson et al. 1978). Reaction with ozone or peroxyacetyinitrate yields diones nitrogen oxide reactions yield nitro and dinitro PAHs. Sulfonic acids have also been formed from reaction with sulfur dioxide. 

An example in which formation of a carbon radical is not the initial reaction is provided by the atmospheric reactions of organic sulfides and disulfides. They also provide an example in which rates of reaction with nitrate radicals exceed those with hydroxyl radicals. 2-dimethylthiopropionic acid is produced by algae and by the marsh grass Spartina alternifolia, and may then be metabolized in sediment slurries under anoxic conditions to dimethyl sulfide (Kiene and Taylor 1988), and by aerobic bacteria to methyl sulfide (Taylor and Gilchrist 1991). It should be added that methyl sulfide can be produced by biological methylation of sulfide itself (HS ) (Section 6.11.4). Dimethyl sulfide — and possibly also methyl sulfide — is oxidized in the troposphere to sulfur dioxide and methanesulfonic acids. 

Very little information is available on atmospheric reactions of manganese (EPA 1984a). Manganese can react with sulfur dioxide and nitrogen dioxide, but the occurrence of such reactions in the atmosphere has not been demonstrated. 

VIII. Atmospheric Reactions of Selected Nitrogen and Sulfur Compounds... 

Atmospheric reactions modify the physical and chemical properties of emitted materials, changing removal rates and exerting a major influence on acid deposition rates. Sulfur dioxide can be converted to sulfate by reactions in gas, aerosol, and aqueous phases. As we noted in Chapter 17, the aqueous-phase pathway is estimated to be responsible for more than half of the ambient atmospheric sulfate concentrations, with the remainder produced by the gas-phase oxidation of S02 by OH (Walcek et al. 1990 Karamachandani and Venkatram 1992 Dennis et al. 1993 McHenry and Dennis 1994). These results are in agreement with box model calculations suggesting that gas-phase daytime S02 oxidation rates are l-5% per hour, while a representative in-cloud oxidation rate is 10% per minute for 1 ppb of H202. 

EXPLOSION and FIRE CONCERNS powdered form is combustible NFPA rating Health 0, Flammability 2, Reactivity - violent or explosive reaction when heated with ammonium nitrate ignites or reacts violently with bromine pentafluoride incandescent reaction with nitrogen oxide or sulfur dioxide reaction with mineral acids may liberate hydrogen gas reacts readily with dilute acids to form chromous salts incompatible with oxidants potentially explosive in atmospheres of carbon dioxide use dry chemical, carbon dioxide, water spray, fog, or sand for firefighting purposes. 

Atmospheric reactions modify the physical and chemical properties of emitted materials, changing removal rates and exerting a major influence on acid deposition rates. Sulfur dioxide can be converted to sulfate by reactions in gas, aerosol, and aqueous phases. As we... 

Lee, T. J. and A. P. Rendell (1993) Ab initio characterization of peroxyhypochlorous acid implications for atmospheric chemistry. Journal of Physical Chemistry 97, 6999-7002 Lee, Y- N., J. Shen, P. J. Klotz, S. E. Schwartz and L. Newman (1986) Kinetics of hydrogen peroxide - sulfur(IV) to sulfur(VI) reaction in rainwater collected at a northwestern US. site. Journal of Geophysical Research 91, 13264-13274... 

What is the serious air pollution phenomenon resulting from an atmospheric reaction of sulfur dioxide ... 

Carbonyl sulfide COS is a sulfur compound present in the troposphere at ca. 0.5 ppbv. It is emitted from volcanic activities and also formed in the atmospheric reaction of CS2 and OH as mentioned above. Among the global emissitm of COS, the ratio of the secondary formation from CS2 is estimated to be ca. 30 % (Chin and Davis 1993). The rate constant of the reaction of COS an OH is very small as seen in Table 5.2 (2 x 10 cm molecule s at 298 K), and the atmospheric lifetime calculated from the average concentration of OH assumed to be 8 x 10 molecules cm is about 20 years. Therefore, most of COS emitted and formed in the troposphere is transported to the stratosphere, where it is photolyzed to yield H2SO4, which causes the stratospheric aerosols (see Chap. 8, Sect. 8.5). 

Compound 36 when treated by sulfur under nitrogen, leads to the thiazoline-2-thione (37) (Scheme 16) (43). Oxidation by O- or air of 36 (43) or 38 (45, 46) leads to the corresponding thiazoiine (39 or 40). Consequently, condensation reactions using catalysts like 36 must be run in strictly oxygen-free atmosphere (47-50). The isolation of traces of 3-benzyl-4-methyl-A-4-thiazoline-2-one (42) as a product of the oxidation of... 

Because of the mixture of VOCs in the atmosphere, the composition of smog reaction products and intermediates is extremely complex. formed via reaction 16, is important because when dissolved in cloud droplets it is an important oxidant, responsible for oxidising SO2 to sulfuric acid [7664-93-9] H2SO4, the primary cause of acid precipitation. The oxidation of many VOCs produces acetyl radicals, CH CO, which can react with O2 to produce peroxyacetyl radicals, CH2(C0)02, which react with NO2... 

Production of hydrogen fluoride from reaction of Cap2 with sulfuric acid is the largest user of fluorspar and accounts for approximately 60—65% of total U.S. consumption. The principal uses of hydrogen fluoride are ia the manufacture of aluminum fluoride and synthetic cryoHte for the Hall aluminum process and fluoropolymers and chlorofluorocarbons that are used as refrigerants, solvents, aerosols (qv), and ia plastics. Because of the concern that chlorofluorocarbons cause upper atmosphere ozone depletion, these compounds are being replaced by hydrochlorofluorocarbons and hydrofluorocarbons. 

Chemica.1 Properties. With few exceptions, SF is chemically inert at ambient temperature and atmospheric pressure. Thermodynamically SF is unstable and should react with many materials, including water, but these reactions are kineticaHy impeded by the fluorine shielding the sulfur. Sulfur hexafluoride does not react with alkah hydroxides, ammonia, or strong acids. 

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