Sunlight photolysis

Photolysis calculated t,/2 = 22 h for direct sunlight photolysis of 50% conversion at 40°N latitude of midday in midsummer in near surface water, t,/2 = 180 d in 5-m deep inland water and t,/2 = 190 d in inland water with a suspended sediment concentration of 20 mg/L partitioning (Zepp Schlotzhauer 1979) t,/2 = 180 d under summer sunlight in surface water (Mill Mabey 1985) direct photolysis t,/2 = 11.14 h (predicted- QSPR) in atmospheric aerosol (Chen et al. 2001). 

I jcalc) = 0.75 h near surface water for direct sunlight photolysis at 40°N latitude of midday in midsummer (quoted, Herbes et al. 1980 Harris 1982)... 

Photolysis calculated t,/2 = 4.2 d for direct sunlight photolysis in midday of midsummer at 40°N for inland water, and t,/2 = 5.9 d for inland water with sediment partitioning (Zepp Schlotzhauer 1979) k= 1.014 h-1 (Zepp 1980)... 

Air t,/2 = 0.68-2.04 h, based on estimated sunlight photolysis half-life in water (Zepp Stotzhauer 1979 Lyman et al. 1982 quoted, Howard et al. 1991) ... 

Chemicals will undergo photolysis if they can absorb sunlight. Photolysis can occur in air, soil, water, and plants. The rate of photolysis is dependent upon the pH, temperature, presence of sensitizers, sorphon to soil, depth of the compound in soil and water. Lyman et al. (1982) present an excellent overview of the photolysis process. 

Photolytic. Photolysis of thin films of solid endrin using UV light X = 254 nm) produced 5-ketoendrin and endrin aldehyde and other compounds (Rosen et al., 1966). When exposed to sunlight for 17 d, endrin completely isomerized to 5-ketoendrin (1,8 eYO-9,10,11,11-hexachloro-yclo[6.2.1.1 .0 0 °]dodecan-5-one) and minor amounts of endrin aldehyde (Burton and Pollard, 1974). Irradiation of endrin by UV light X = 253.7 and 300 nm) or by natural sunlight in cyclohexane and hexane solution resulted in an 80% yield of l,8-eA o-9,ll,ll-pentachloro-cyclo[6.2.1.1 0 0 °]dodecan-5-one (Zabik et al, 1971). This compound also formed from the sunlight photolysis of endrin in hexane solution (Fujita et al., 1969). 

Lee et al. (1999a) reported that terbufos sulfoxide is the major product of sunlight photolysis of terbufos. Terbufos sulfoxide was reported as a minor product. In distilled, deionized, unbuffered water, the experimental photolysis half-life was 56 min. 

Tanaka. F.S., Hoffer, B.L., and Wien. R.G. Detection of halogenated biphenyls from sunlight photolysis of chlorinated herbicides in aqueous solution. Pestle. Scl, 16(3) 265-270, 1985. 

One such reaction in smog formation is the formation of the acetyl radical such as by sunlight photolysis of acetaldehyde... 

Direct-sunlight photolysis of 2-benzoyl-3-phenylquinoxaline 1,4-dioxide (227) yields the ring-contracted product, l,3-dibenzoyl-2-benzimidazolone (228) (70%).53,228... 

The loss of H202 in natural waters by direct sunlight photolysis was considered of minor importance, but no experimental evidence existed until Moffett and Zafiriou (I) used 1802-labeled H202 in experiments conducted in coastal waters and no significant sunlight photolysis of H202 was observed. 

The chemical pathways for the decomposition of H202 appear to play a minor role in the overall decay processes. Direct-sunlight photolysis is not important in natural waters (I). The effect of H202 on metal speciation, and therefore on H202 decomposition, has been demonstrated in marine systems but not in lakes. Additional studies are required to better understand these processes in lake waters. 

Cycloaddition of a ketene complex with unsaturated bonds other than alkenes and alkynes is also possible. The ketene 312, formed from 311, adds to imine 313 to give the /1-lactam 314 under sunlight photolysis. The optically active /1-lactam 314 was prepared from the optically active carbene complex 311 with 99% ee, and converted to 315 [95]. Irradiation of carbene complex 316 generates ketene 317, which cyclizes to the o-hydroquinone derivative 318 [96],... 

Nearly all thin film photolysis studies involving triazine herbicides have utilized model surfaces such as filter paper (Jordan et al., 1964 Morita et al., 1988), aluminum (Jordan et al., 1965), glass (Pape and Zabik, 1972 Chen et al., 1984 Hubbs and Lavy, 1990), and silica gel (Lotz et al., 1983). A shortcoming of the use of model surfaces is that herbicide dissipation due to volatility losses is often not accounted for (Hubbs and Lavy, 1990). Konstantinou et al. (2001) studied the sunlight photolysis of atrazine, propazine, and prometryn on soil (sandy clay loam, clay loam, and... 

Pesticides are known to be associated with atmospheric aerosols and thus may be subject to sunlight photolysis in the sorbed state. The photodegradation of triazine herbicides has been investigated when sorbed to suspended aerosols of kaolin and fly ash (Bossan et al, 1995), and silicon dioxide (Palm et al., 1997a). 

The photolysis of metamitron requires both oxygen and water. No photoreaction of metamitron was observed in methanol, acetonitrile, hexane, or oxygen-free water (Palm et al., 1997b). Soil humic acids photosensitized the photolysis of metamitron in water (Cox et al., 1996). However, a slower rate of sunlight photolysis of the herbicide was observed when metamitron was present as a complex with copper (II) (Sancho et al., 1997). 

Surface water direct sunlight photolysis in aquatic bodies at latitude 40°N for various seasons with half-lives 0.35 d in spring, 0.31 d in summer, 0.53 d in fall, 0.84 d in winter and 1.47 d averaged over full year (Choudhary Webster 1986) ... 

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