Mechanism of photooxidation

However, the detailed mechanism of photooxidation of S02 is still unknown [Sidebottom et al. (879)]. 

Manring, L.E. and Foote, C.S. (1983) Chemistry of singlet oxygen. 44. Mechanism of photooxidation of 2,5-dimethyl-2,4-diene and 2-methyl-2-pentene. Journal of the American Chemical Society, 105, 4710-4717. 

The foregoing and, in particular, the reactivity of the 2-oxopyrimidine radical in DMSO, is relevant to the mechanism of photooxidation of the 2-oxopyrimidine dimer to the monomer on irradiation at 254 nm in DMSO 83). The initial step in the latter process would be the formation of a protonated neutral free radical, RH). which is rapidly oxidized (—0.8 V) to RH), followed by deprotonation. 

The first step of the mechanism of photooxidation of PS is the abstraction of a hydrogen atom on the tertiary carbon of the macromolecule structure, which... 

The free radical(s) so formed are then scavenged by molecular oxygen forming the peroxy radical or anion (Reaction 5) thus leading to the oxidation of the acceptor AH. This is called the Type I mechanism of photooxidation. 

Studies of the rate and mechanism of photooxidation of aldehydes in the vapor phase have been particularly concentrated on ethanal and propanal. Here again, to eliminate any possible kinetic influence of the reaction products, the authors have paid particular attention to the initial rate of reaction. 

Up to now, we have only considered the initial phases of kinetics and mechanism of photooxidation of an aldehyde to the corresponding per acid (the main molecular product). If we try to examine these reactions as a function of time, it becomes clear that frequently new processes intervene to complicate the reaction mechanism, as is the case in many chemical reactions. 

Ermolenko, L. P. Delaire, J. A. Giannotti, C. Laser flash photolysis study of the mechanism of photooxidation of alkanes catalyzed by decatungstate anion. J. Chem. Soc. - Perkin Trans, mi, 2, 25-30. 

Mechanism of Photooxidation of Spirooxazines Singlet-Oxygen Reactivity... 

About the Mechanism of Photooxidative Destruction OF Cellulose Acetate... 

When it was proved that singlet oxygen takes part in reactions of photosensibilized oxidation Trossol and Winslow have suggested new mechanism of photooxidative destruction of polyesters including 4 stages [242] ... 

Gugumus, F. "Mechanisms of Photooxidation of Polyolefins." Die Angewandte Makromolekulare Chemie 176/177(1990) 27-42. 

The mechanism of photooxidation of petroleum probably includes significant contributions from both radical and singlet oxygen pathways. Petroleum contains polycyclic aromatic hydrocarbons and other compounds with known photosensitizing activity Lichtenthaler et al. (1989) demonstrated quantum yields for O2 formation ranging from 0.5 to 0.8 for a number of crude oils. The photooxidation of a 2 fuel oil was inhibited by /3-carotene, an excellent quencher of O2 and free radicals, at concentrations > lO" M (Larson and Hunt, 1978). A mechanism incorporating... 

Glickman, R.D., 1998. Mechanisms of Photooxidative Stress in Retinal Pigment Epithelium Is Melanin a Photosensitizer Technical Report ADA384222, DTIC Online, Defense Technical Information Center, Ft. Belvoir, VA, USA. 

Hutt, D.A., Cooper, E., Leggett, G.J. (1998) Structure and mechanism of photooxidation of self-assembled mono-layers of alkylthiols on silver studied by XPS and static SIMS. /. Phys. Chem. B, 102,174-184. 

Stenburg, V.I. Wang, C.T. Kulevsky, N. Photochemical oxidations. III. Photochemical and thermal behavior of a-hydroperoxytetrahydrofuran and its implications concerning the mechanism of photooxidation of ethers. J. Org. Chem. 1970, 35, 1774-1777. 

Mechanisms of Photooxidation of Polyolefins Prediction of Lifetime in Weathering Conditions, In Polymer Durability, American Chemical Society Publication, 1996... 

Phifippart, J.-L., Sinturel, C., Amaud, R., Gardette, J.-L. Influence of the exposure parameters on the mechanism of photooxidation of polypropylene. Polym. Degrad. Stab. 64, 213-225 (1999)... 

The mechanism of photooxidation of aromatic species in the atmosphere is perhaps the area of greatest incertainty in atmospheric hydrocarbon chemistry. The principal reaction of aromatics is with the hydroxyl radical. Absolute rate constants have recently been determined at room temperature for the reaction of OH radicals with benzene and toluene (l8,l ) and with a series of aromatic hydrocarbons (19). Recently, absolute rate constants for the reaction of OH radicals with a series of aromatic hydrocarbons have been determined over the temperature range 296-U73K (20). For aromatic-OH reactions, the initial step can be either abstraction or addition to the aromatic ring. For toluene, for example. 

From the foregoing it appears to us that the mechanism of photooxidation of the dimers under aerobic and anaerobic conditions is as shown in Scheme 2 and that in the presence of oxygen there is the additional reaction... 

Shishido T, Miyatake T, Teramiua K, Hitomi Y, Yamashita H, Tanaka T (2009) Mechanism of photooxidation of alcohol over Nb205. J Phys Chem C 113(43) 18713-18718... 

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