Light induced degradation

Water-soluble sdanols such as (1) were found to undergo successive oxidative demethylations with tropospheric ultraviolet irradiation in the presence of suitable chromophores, such as nitrogen oxides (516). The water-soluble methylated sdicones did not promote diatom (Nap cu/apelliculosd) growth but the demethylated photo products did. The sequence of sod-induced degradation of sdicones to water-soluble species such as (1), followed by light-induced conversion to sdicate, suggests a pathway, conceptually at least, for the mineralization of sdicones. 

Zhang, X. and Liu, Q. (2008) Visible-light-induced degradation of formaldehyde over titania photocatalyst co-doped with nitrogen and nickel. Applied Surface Science, 254 (15), 4780-4785. 

Two commercial disazo disperse dyes of relatively simple structure were selected for a recent study of photolytic mechanisms [180]. Both dyes were found to undergo photoisomerism in dimethyl phthalate solution and in films cast from a mixture of dye and cellulose acetate. Light-induced isomerisation did not occur in polyester film dyed with the two products, however. The prolonged irradiation of Cl Disperse Yellow 23 (3.161 X = Y = H) either in solution or in the polymer matrix yielded azobenzene and various monosubstituted azobenzenes. Under similar conditions the important derivative Orange 29 (3.161 X = N02, Y = OCH3) was degraded to a mixture of p-nitroaniline and partially reduced disubstituted azobenzenes. 

B. Neppolian, H.C. Choi, S. Sakthivel, B. Arabindoo and V. Murugesan, Solar light induced and Ti02 assisted degradation of textile dye reactive blue 4. Chemosphere, 46 (2002) 1173-1181. 

The amount of TiO was varied, and the assembly was tested for its photocata-lytic activity using degradation of 2,4-xylidine as test reaction probe. The decrease in the concentration of xylidine and the corresponding increase in oxalate concentration were monitored through HPLC. A pseudo-first order kinetics was ob served in the photodegradation process based on the Langmuir-Hinshelwood mechanism. An inverse correlation was observed between the kinetic rate constant and the obtained Light-Induced Optoacoustic Spectroscopy (LIOAS) frequency maxima. 

Two different kinds of cleavage protocols were investigated. The first was a light induced photo-release reaction followed by a chromatographic work-up. Also, reaction monitoring was performed by MALDl/TOF/MS since the LASER cleaves the disaccharide from the support The second is a hydrolytic cleavage reaction under degradation of the polymeric support and subsequent aqueous extraction to yield the pure product The disaccharides (20) were obtained in yields of 27-76%. 

The material considered here allows us to understand the influence of sterically hindered amines, which act as stabilizers against the light-induced degradation of polyolefines. The sterically hindered amines easily undergo oxidation after cation-radical formation ... 

Stylidi, M Kondarides, DI Verykios, XE. Pathways of solar light-induced photocatalytic degradation of azo dyes in aqueous Ti02 suspensions. 

Becker, AnalChem 22, 185-88(1950) CA 44, 3407 (1950) (Detn of N-contg functional groups in org compds) 9) O. Siis et al, Ann 598, 123-38(1956) CA 51, 321-23(1957) (Light-induced degradation products of diazo derivs) 10) LA. D yakonov, "Alifatiches-kie Diazosoedineniya (Aliphatic Diazo Compounds), Izdatel , Leningrad, Moscow(1958), 138 pp... 

The Importance of Sunlight in Industry. Sunlight is hardly ever used nowadays for quantitative laboratory photochemical research, but it remains the most important light source for many indirect industrial applications which involve the light-induced degradation of chemicals. 

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