- Singlet oxygen mediated oxidation of olefins within zeolites: Selectivity and complexities
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Thiazine dyes such as thionin, methylene blue and methylene green have been cation exchanged within monovalent cation exchanged Y zeolites. Depending on the water content, the dye molecules exist as either monomers ('dry') or dimers ('wet'). The monomeric
- Shailaja,Sivaguru,Robbins, Rebecca J.,Ramamurthy,Sunoj,Chandrasekhar
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- Zeolite matrix assisted decomposition of singlet oxygen sensitizers during photooxidation
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Thiazine dyes such as thionine, methylene blue and methylene green were exchanged within monovalent cation exchanged Y zeolites. Depending on the water content the dye molecules exist as either monomer (‘dry’) or dimer (‘wet’). The monomeric dye is effect
- Shailaja,Sivaguru,Ramamurthy
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p. 197 - 205
(2016/11/16)
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- Regioselective radical cyclization initiated by the reaction of allylic hydroperoxides with iron(II) sulfate
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Treatment of 1-methyl-2-methylene-1-cyclohexyl hydroperoxide with a mixture of FeSO4/CuCl2 yielded 1-(1-chlorocyclohexyl)ethanone as the major product consistent with 6-endo-trig cyclization of the intermediate 5-acetylhex-5-enyl rad
- Masuyama, Araki,Sugawara, Tomohiro,Nojima, Masatomo,McCullough, Kevin J.
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p. 353 - 366
(2007/10/03)
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- GAS PHASE GENERATION OF SINGLET OXYGEN AT ATMOSPHERIC PRESSURE
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Evidence is presented for the gas phase generation of singlet oxygen using heterogeneous photosensitization and atmospheric pressure.
- Eisenberg, Walter C.,Snelson, Alan,Butler, Ronald,Veltman, James,Murray, Robert W.
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p. 377 - 380
(2007/10/02)
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- Mechanism of the Direct Reaction of Phosphite Ozonides with Olefins
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The direct reaction of triphenyl phosphite ozonide (TPPO) with olefins, occurring at low temperatures where no thermal generation of singlet oxygen occurs, is observed in identical fashion with a caged-ring and two o-phenylene phosphite ozonides whose thermal generation of singlet oxygen is very slow compared to TPPO.Biadamantylidene, which is quite reactive toward singlet oxygen, appears totally hindered against the direct reaction with TPPO.In the case of Δ2-dihydropyran the direct reaction contrasts strongly with the behavior toward singlet oxygen in that (1) ene reaction is only one-tenth as great as dioxetane formation, (2) the importance of ene reaction is not a function of solvent polarity, and (3) ene reaction is inhibited by free-radical scavengers.In the case of tricyclopropylethylene, the formation of allylic hydroperoxides in the case of singlet oxygen is replaced in the direct TPPO reaction by cleavage to ketone and aldehyde under conditions where the hydroperoxides are stable and hence cannot be intermediates.The direct reaction of TPPO with 1,2-dimethylcyclohexene and 2-methyl-2-butene gave mixtures of ene products similar to those from singlet oxygen and, in the case of the former hydrocarbon, quite different from the product of chain oxidation.Dabco, tetramethyl-p-phenylenediamine, and other tertiary amines rapidly decompose phosphite ozonides to phosphate and ground-state oxygen, with evidence of electron transfer from the amines.In this and in the direct oxygenation of dihydropyran, the 31P NMR signal goes directly from 63 to 17 ppm, showing that there is no detectable intermediate state of phosphorus between TPPO and phosphate.The facts are accommodated by a mechanism involving initial bond formation between the olefin and thecenter oxygen atom of the ozonide, with chemical and sterochemical sequels which are discussed.The freezing point of chloroform is depressed to the same extent by TPPO as by triphenylphosphate, showing that TPPO is monomeric.
- Bartlett, Paul D.,Chu, Hsien-Kun
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p. 3000 - 3004
(2007/10/02)
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