Singlet chemical sources

Chemical sources. An early chemical source is the reaction of HOC1 with H2O2, which produces singlet C f4 A) in nearly quantitative yield ... 

A new chemical source of singlet molecular oxygen ( Oj, Ag), H20 /Ca(0H)2, has been investigated in detail. First, the formation of O2 has been proved unambiguously by resorting both to the specific detection of the IR luminescence at 1270 nm of O2 and to the chemical trapping of the excited species with a new cationic water-soluble trap. The process has been shown to be catalytic and the influence of several parameters (pH, concentrations and purities of reactants) on the initial rate of O2 formation has been examined. Finalfy, the ability of the system H202/Ca(0H)2 to oxidize various water-soluble electron-rich substrates has been assessed. 

J. M. Aubry, New chemical sources of singlet o grgen, in Membrane lipid oxidation , Vol. n, Ed. Vigo-Pelfrey, CRC Boca Raton, (1990) 65-101. 

Aubry J M. Chemical sources of singlet oxygen. 3. Peroxidation of water soluble singlet oxygen carriers with the hydrogen peroxide-molybdate system. J Org Chem 1989 54 726-8... 

Nardello, V. et al.. Photochemistry without light Oxidation of ruhrene in a microemulsion with a chemical source of singlet molecular oxygen ( O2, Dg), J. Chemical Education, 76, 1285, 1999. 

Figure 22.5 Schematic representation of the dark singlet oxygenation of a substrate S in a water-in-oii singie-phase jem water/surfactant/cosurfactant/solvent by the chemical source hydrogen peroxide/sodium molybdate.

The reaction of potassium superoxide with water is the single most important chemical source of oxygen for breathing purposes in hospitals, mines, submarines (Clarke 1956), and space capsules (Bovard 1960). Even if only a small fraction of singlet oxygen survives quenching, it could prove to be a serious health hazard (Khan 1970). 

Oxo-2 -de0xyguanosine was found to be the main Oj oxidation product of DNA upon exposure to either a chemical source of singlet oxygen or excited photosensitizers (Muller et al. 1990, Schneider et al. 1990, Devasagayam et al. 1991). 

Potassium perchromate is a chemical source of singlet oxygen. ... 

Nevertheless, in the sensor study of heterogeneous reactions of singlet oxygen, it is better to employ selective sources that do not generate other active particles and produce though low, but stable concentrations of 02( ). These sources can be photochemical and chemical... 

Bis-(2,4,6-tricholophenyl)oxalate (TCPO) reacts with hydrogen peroxide to form a proposed energetic intermediate, 1,2-dioxethanedione, which transfers its energy to a lluorophor via a proposed electron transfer and excites it to the first excited singlet state followed by the emission of a photon. The reason for the interest in CL detection is that chemical excitation, as opposed to conventional photoexcitation, is lower, because of the lack of problems from scattering and fluctuations of the source. 

In addition to the above sources, a number of other chemical reactions have been suggested for the production of singlet oxygen. 

Martinez, G.R., Ravanat, J.-L., Medeiros, M.H.G., Cadet, J. and Di Mascio, P. (2000) Synthesis of a naphthalene endoperoxide as a source of lsO-labeled singlet oxygen for mechanistic studies. Journal of the American Chemical Society, 122 (41), 10212-10213. 

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