Oxygen, irradiation

Nitroso-5//-dibenz[/>,/]azepine (9, R = NO) is relatively stable to photolysis under argon, whereas in benzene solution in the presence of oxygen, irradiation induces an oxidative Fischer -Hepp-type rearrangement to 2-nitro-5//-dibenz[6,/]azepinc (10, R = N02), accompanied by ring contraction to acridine-9-carbaldehyde184 (see also Section 3.2.2.4.). 

Oster [174] proposed the second hypothesis to explain his results on the photopolymerization of acrylonitrile in aqueous solution, buffered at pH 7.0, and sensitized by xanthene dyes and riboflavin using ascorbic acid as the reducing agent. Whereas the monomer is efficiently polymerized when the solution is illuminated in the presence of oxygen, irradiation in its absence leads to photoreduction of the dye to its leuco form but no polymer is formed. Therefore, the author suggests that the leuco dye reacts with atmospheric... 

FIG. 21.—Quantities (Q) [mg/mL] of water-soluble dextrins as a function of water content (W) in potato starch (o, irradiation under oxygen , irradiation under nitrogen) (from Ref. 101). 

Loader and Timmons have described a number of photocyclizations which involve coupling with a heterocyclic ring in the presence of atmospheric oxygen. Irradiation of fraras-4-styrylquinoline (122) in hexane or cyclohexane gives 7,8-benzophenanthridine (124).161-163 In the latter solvent a small amount of 6-cyclohexyl-7,8-benzo-phenanthridine, resulting from the photochemical reaction between 7,8-benzophenanthridine and the solvent, has been isolated alkyla-... 

The final group of changes, those below 260 nm, were somewhat more pronounced in the oxygen irradiations, but still significant in nitrogen. These changes were largely associated with the alcohol-soluble products. These alcohol extracts have low absorbances in the typical... 

Activity, and Yield of Products Formed from Its Oxygenated Irradiated by the Doses 1.36 to 131.7 X 105 rada... 

Huyghebaert, C., Conard, T, Brijs, B., Vandervorst, W. (2004) Impact of the Ge concentration on the Ge-ionisation probability and the matrix sputter yield for a SiGe matrix under oxygen irradiation. Applied Surface Science, 231-232,708-712. 

Water purification. Semiconductor systems, such as particulate Ti02> have already demonstrated the possibility of oxidation of contaminants such as C, S02> and organics in aqeous solutions in the presence of oxygen. Irradiated semiconductors are very potent oxidizing agents, since hydroxyl radical is produced in some systems. Semiconductor dispersions should also be useful for disinfection and the oxidation of even very resistant organic molecules. 

Heymann et al. ° as well as Smith etal. ° reported the synthesis of C70O 31 by photo-oxygenation. Irradiation of an oxygenated toluene solution of C70 using rubrene as a sensitizer resulted in the formation of a nearly 1 1 mixture of two C70O isomers 31a and 31b, which cannot be separated (Figure 28.6). No evidence for the formation of isomers 31c and 31d was found. 

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