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Photo-oxidation products

E.S.B. Ferreira, A. Quye, H. McNab, A.N. Hulme, Photo oxidation products of quercetin and morin as markers for the characterisation of natural flavonoid yellow dyes in ancient textiles, Dyes in History and Archaeology 18, 63 72 (2002). [Pg.35]

Investigation turned then to chemical and spectroscopic means to obtain the needed mechanistic understanding. Stephenson et al. [17] looked at gas evolution versus exposure, while Pacifici and Straley [18] used UV fluorescence spectroscopy to identify a photo-oxidation product which was later isolated by Valk et al. [19]. In addition, Valk and co-workers [19-21] isolated a number of additional photolysis products by a combination of hydrolysis and chromatography, Marcotte et al. [22] used ESR to look at radicals generated during degradation, and Day and Wiles [23-26] carried out extensive IR and fluorescence spectroscopic investigations on this subject. [Pg.628]

Recently, Itaya, Okamoto and Kusabayashi (14) made an estimation that the concentration of the electron-accepting photo-oxidation product of about 10 mol/mol monomer unit is necessary to interpret the high yield of the photocarrier generation of ca. [Pg.214]

Photo-oxidation of trimethylethylene was frequently used as evidence to support or contradict various mechanistic possibilities for the ene reaction. For example, the equal amounts of photo-oxidized products (olefin 4) led to the conclusion that the ene reaction proceeds without any regioselectivity (Scheme 5). [Pg.250]

Ehrhardt M. 1987. Photo-oxidation products of fossil fuel components in the water of Hamilton Harbour, Bermuda. Marine Chemistry 22 85-94. [Pg.143]

The two most probable loss processes of phosgene in the stratosphere are photolysis, and transport into the troposphere. Phosgene can be formed in situ in the stratosphere [36a], and indeed it is one of the main photo-oxidation products in the upper troposphere and lower stratosphere from the breakdown of chlorinated hydrocarbons (of both natural and anthropogenic origin). For example, the relatively inert tetrachloromethane accumulates in the air, but can photodissociate in the stratosphere according to ... [Pg.164]

W. Graneli, M. Lindell, L. Tranvik (1996). Photo-oxidative production of dissolved inorganic carbon in lakes of different humic content. Limnol. Oceanogr., 41,698-706. [Pg.215]

Hamilton, J.F., A.C. Lewis, C. Bloss, V. Wagner, A.P. Henderson, B.T. Golding, K. Wirtz, K, M. Martin-Reviejo and M.J. Pilling Measurements of photo-oxidation products from the reaction of a series of alkyl-benzenes with hydroxyl radicals during EXACT using comprehensive gas chromatography. Atmos. Chem. PAys., 3, (2003) 1999-2014. [Pg.154]

The photo-oxidation products of carbon disulfide in the laboratory were identified as carbon monoxide, carbonyl sulfide, sulfur dioxide, and a polymer that adhered to the sides of the reaction vessel (Heicklen et al. 1971). Although carbon disulfide absorbs light at wavelengths between 280 and 350 nm, dissociation does not occur under environmental conditions because of low molar absorptivity (Atkinson et al. 1978 Wood and Heicklen 1971) and direct photolysis of carbon disulfide in the atmosphere does not appear to be significant. EPA (1978a) stated that the information available indicated that carbon disulfide is relatively persistent in the atmosphere. For the atmospheric oxidation of carbon disulfide to sulfur dioxide, carbonyl sulfide, and carbon monoxide, the half-life was estimated to be about 12 days. [Pg.145]

Cox, G.S., Bobillier, C., and Whitten, D.G. (1982) Photo-oxidation and singlet oxygen sensitization by protoporphyrin IX and its photo-oxidation products, Photochem. Photobiol., 36 401 407. [Pg.203]

The fact that molecular movements in the solid state are restricted and that the sample permeability to oxygen and moisture can be low may lead to an alteration in product formation compared to the drug in solution. This is illustrated by formation of new rotamers in the solid-state degradation of tolrestat favoring of the redox product in the solid-state degradation of nifedipine compared to the photo-oxidation product observed in solution or by diversity in degradation products of santonins in solution and in the solid state (Reisch et al., 1986 Lee and Lee, 1990 Marciniec and Rychcik, 1994). These observations emphasize that results obtained on the drug substance in solution are not necessarily valid for the solid state. [Pg.355]

Brossi, A., Gessner, W., Hufford, C.D., Baker, J.K., Homo, F., Millet, P, and Landau, I. (1987) Photo-oxidation products of primaquine. Structure, antimalarial activity and hemolytic effects, FEBS Lett., 223, 77-81. [Pg.403]

The ketonic products can be expected to occur in trace amounts in pure polymers and are also components of the complex photo-oxidation products. Photolytic reactions of these ketones are important both in the very early stages of photo-oxidative degradation and in the continuation of an established photo-degradation reaction. The ketones may affect the source of the photodegradation by contributing to free radical processes, chain scission and energy transfer. [Pg.447]

Haaf, W., and R. Jaenicke (1977). Determination of the smallest particle size detectable in condensation nucleus counters by observation of the coagulation of S02 photo-oxidation products. J. Aerosol Sci. 8, 447-456. [Pg.663]

We are advancing in the study of the photocatalytic oxidation of hydrocarbons using the TiOz/metal porphyrin hybrid catalyst and, herein, we report on the importance of surface tayloring of the TIO2 catalyst in order to improve the yields in cyclohexane oxidation. Results of the photo-oxidation of n-heptane and methylcyclohexane are also reported. In this case, the distribution of the photo-oxidation products provides some insight in how the regioselectivity is affected by the surface modification. [Pg.409]

Large quantities of dichlorodifluoromethane and other chlorofluorocarbons ( Freons ) are used as aerosol propellants, and it has been calculated that there is a danger of reducing the earth s protective ozone layer following photolysis to produce chlorine atoms in the upper atmosphere.184 Milstein and Rowland185 have now measured quantum yields of unity for CF2C12 dissociation [reaction (36)] and for appearance of photo-oxidation products in oxygen. Studies of the... [Pg.420]

Both Mg/MCM-41 systems exhibited further lower selectivity to CO2, and a distribution of the partial photo-oxidation products different fiom the pure MCM-41. The Mg/MCM-41 (15M) sample showed a good selectivity to AA (Table 1, entry 2), while the Mg/MCM-41 (15W) sample exhibited an improved selectivity to AC (Table 1, entry 3). When compared to the bare MCM-41, a significant increase in the selectivity towards PA was obtained in the case of Mg/MCM-41 (15M) (Table 1, entry 2), while the Mg/MCM-41(15W) sample shows a significant increase of the selectivity towards both AC and PA (Table 1, entry 3). [Pg.338]

As examples of other naphthalenoid ansamycin antibiotics, rubradirin (70) and protorubradirin (71) were isolated from the fermentation broth of Streptomyces achromogenes var. rubradiris [109-114,117]. As indicated previously, protorubradirin (71) is the C-nitroso-analogue of 70, and it seems that 71 is the true secondary metabolite produced by S. achromogenes var. rubradiris. Thus, rubradirin (70), reported earlier, is the photo-oxidation product of protorubradirin (71). The ansa moiety of these compounds possesses a C9 chain, instead of a C or a C23 chain. [Pg.88]

Aoki et al. (1974) sensitized guinea pigs by repeated cutaneous applications of / -hydroxylaminobenzene sulfonamide (PHABSA), a photo-oxidation product of sulfanilamide (SNA). On challenge with the substance, a marked cutaneous inflammation and an elevation of histamine level in the lesions are observed, although a single application of PHABSA to the nonsensitized animals elicits neither of these reactions. In addition, the cutaneous changes and elevation of histamine... [Pg.527]


See other pages where Photo-oxidation products is mentioned: [Pg.194]    [Pg.139]    [Pg.697]    [Pg.214]    [Pg.214]    [Pg.70]    [Pg.342]    [Pg.342]    [Pg.191]    [Pg.767]    [Pg.244]    [Pg.39]    [Pg.255]    [Pg.37]    [Pg.232]    [Pg.134]    [Pg.165]    [Pg.496]    [Pg.767]    [Pg.28]    [Pg.195]    [Pg.238]    [Pg.343]    [Pg.411]    [Pg.69]    [Pg.172]    [Pg.415]    [Pg.194]   
See also in sourсe #XX -- [ Pg.407 ]




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