REACTIVITIES IN PHOTOSENSITIZED OLEFIN OXIDATIONS

1965 ◽  
Vol 43 (8) ◽  
pp. 2265-2270 ◽  
Author(s):  
Karl R. Kopecky ◽  
Hans J. Reich
Keyword(s):  
Methylene Blue ◽  
Singlet Oxygen ◽  
Reactive Intermediate ◽  
Photosensitized Oxidation ◽  
Photo Oxidation ◽  
Oxidation Of Olefins

The rate of the methylene blue photosensitized oxidation of olefins increases in the order: 1-nonene < 4-methylcyclohexene < cyclohexene < 2,3-dimethyl-1-butene < 2-hexene < cyclopentene < 1-methylcyclohexene < 2,3-dimethylcyclohexene < 1-methylcyclopentene < 1,2-dimethylcyclohexene < 2,3-dimethyl-2-butene. The last compound is oxidized 5 500 times as fast as cyclohexene. Comparison of this reactivity sequence with those obtained in other reactions confirms that the reactive intermediate in the photosensitized oxidations is electrophilic. The relative rates (kA/kB) of photo-oxidation of 1-methylcyclopentene (A) and of 1-methylcyclohexene (B) are 10 and do not vary significantly with five different sensitizers. Thus the same reactive intermediate, presumably singlet oxygen, is formed using each of the five sensitizers.

Photosensitized oxidation of 9,10-dimethylanthracene with singlet oxygen by using a safranin O/silica composite under visible light

2015 ◽  
Vol 14 (3) ◽  
pp. 597-602 ◽  
Author(s):  
Elim Albiter ◽  
Salvador Alfaro ◽  
Miguel A. Valenzuela
Keyword(s):  
Visible Light ◽  
Singlet Oxygen ◽  
Second Step ◽  
Homogeneous Reaction ◽  
Photosensitized Oxidation ◽  
Photo Oxidation ◽  
The Third ◽  
Silica Composite ◽  
Safranin O

The photo-oxidation of DMA could be carried out in 3 steps: the first step is the photosensitized production of 1O2 near the surface of the composite; the second step is the diffusion of 1O2 from the surroundings of the surface to the solvent and the third step is the homogeneous reaction between 1O2 and DMA.

scholarly journals On the Involvement of Singlet Oxygen in the Biosynthesis of Oxygenation Products of the Furocoumarin Imperatorine

1984 ◽  
Vol 39 (10) ◽  
pp. 1433-1441 ◽  
Author(s):  
Nicolaas J. de Mol ◽  
Johannes Reisch ◽  
Gerardus M. J. Beijersbergen van Henegouwen
Keyword(s):  
Methylene Blue ◽  
Visible Light ◽  
Protective Effect ◽  
Singlet Oxygen ◽  
Oxidation Products ◽  
Photo Oxidation ◽  
Uva Light ◽  
Β Carotene

The role of singlet oxygen (1O2) in the photo-oxidation of the furocoumarin im peratorine was investigated in vitro. Irradiation with visible light and sensitization with methylene blue yielded the imperatorine oxidation product isogosferol and the corresponding ketone as main products. The involvement of 1O2 was dem onstrated by studying the rate of oxidation under conditions that affect the lifetime of 1O2. Com pared to a range of other furocoumarins, im peratorine appeared to be moderately active as a 1O2 generator. The extent of 1O2 production correlated with the skin sensitizing activity. Upon irradiation of im peratorine itself with UVA light (360 nm) no isogosferol formation is observed, probably as a consequence of its photochemical instability. Irradiation with visible light (λ > 400 nm) of a chlorophyll chromophore containing sensitizer in the presence of imperatorine, yielded isogosferol and the corresponding ketone product. This dem onstrates that in the formation of 1O2 oxidation products of imperatorine in plants naturally occuring sensitizers e.g. chlorophyll and visible light are involved, rather than 1O2 produced by im peratorine or other furocoumarins and UVA light. The protective effect on the chlorophyll sensitized im peratorine oxidation by the 1O2- and chlorophyll triplet quencher β-carotene was demonstrated in a lipophilic solvent.

Efficient photocatalytic oxygenation of alkenes by water soluble sensitizer in organic–water biphasic media

2016 ◽  
Vol 20 (06) ◽  
pp. 670-676 ◽  
Author(s):  
Mahdi Hajimohammadi ◽  
Hoda Ghasemi
Keyword(s):  
Methylene Blue ◽  
Visible Light ◽  
Singlet Oxygen ◽  
Molecular Oxygen ◽  
Rose Bengal ◽  
Room Temperature ◽  
Water Soluble ◽  
Oxygen Production ◽  
Oxidation Of Olefins ◽  
Major Route

A new green, environmentally and economically photooxygenation of olefins by molecular oxygen in the presence of 4-carboxyl tetra phenyl porphyrin (H2TCPP), Rose Bengal (RB), Methylene Blue (MB) and some metallosensitizers (MS) such as cobalt phthalocyaninesulfonate (Coph(SO3H)[Formula: see text], MnTCPPCl, FeTCPPCl and SbTPP(OH)2 as water–soluble sensitizers in organic–water biphasic media at room temperature under visible light was illustrated. The products were obtained with 100% conversion by H2TCPP and 100% selectivity by Coph(SO3H)4. Also in this study, singlet oxygen production as the major route for oxidation of olefins was proved.

The action of rennin on casein: the effect of modifying functional groups on the casein

1965 ◽  
Vol 32 (2) ◽  
pp. 193-201 ◽  
Author(s):  
R. D. Hill ◽  
Raione R. Laing
Keyword(s):  
Methylene Blue ◽  
Amino Acid ◽  
Functional Groups ◽  
Amino Acid Analysis ◽  
Side Chains ◽  
Photo Oxidation

Summaryk-Casein and whole casein when photo-oxidized in the presence of methylene blue lose the ability to clot when treated with rennin. Two effects are involved—first the photo-oxidation alters the k-casein fraction so that the rennin is unable to split off the glycopeptide fragment, and secondly, in whole casein the photo-oxidation interferes with the aggregation in the presence of Ca++that normally follows rennin action. As a result of amino acid analysis and specific treatments which affect other photo-oxidizable side chains, it is concluded that both of these effects are caused by the alteration of histidines.

Singlet-Oxygen Sensitization by Associates of Methylene Blue with Colloidal Ag2S Quantum Dots Passivated by Thioglycolic Acid

2018 ◽  
Vol 125 (1) ◽  
pp. 107-112 ◽  
Author(s):  
O. V. Ovchinnikov ◽  
M. S. Smirnov ◽  
T. S. Kondratenko ◽  
A. S. Perepelitsa ◽  
I. G. Grevtseva ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Quantum Dots ◽  
Singlet Oxygen ◽  
Thioglycolic Acid ◽  
Ag2s Quantum Dots

scholarly journals The generation of the singlet oxygen in methylene blue solution and its effect to the tissue

1987 ◽  
Vol 8 (3) ◽  
pp. 59-60
Author(s):  
Ichiro TANABE ◽  
Hiroshi FUJIMURA ◽  
Tatsuo OTANI ◽  
Yukinori OKAZAKI ◽  
Tadayoshi TAKEMOTO ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Singlet Oxygen ◽  
Methylene Blue Solution ◽  
Blue Solution

Article

1998 ◽  
Vol 76 (12) ◽  
pp. 1805-1816
Author(s):  
L Ross C Barclay ◽  
Jennifer K Grandy ◽  
Heather D MacKinnon ◽  
Heather C Nichol ◽  
Melinda R Vinqvist
Keyword(s):  
Oxygen Uptake ◽  
Singlet Oxygen ◽  
Sodium Azide ◽  
Lignin Content ◽  
Sodium Dodecyl ◽  
Kinetic Studies ◽  
Product Distribution ◽  
Geometrical Isomers ◽  
Photo Oxidation ◽  
Tert Butyl

3,5-Di-tert-butyl-ortho-quinone, 6, and 1-(3,4-dimethoxyphenyl-2-(2-methoxyphenoxy)-1-propanone, 7, models for oxidized lignin and for lignin, were used as sensitizers of photo-oxidation. Product studies by HPLC from oxidation of methyl linoleate in solution sensitized by 6 or 7, and in sodium dodecyl sulfate (SDS) sensitized by 6, showed a product distribution of six hydroperoxides, the four conjugated 9- and 13-hydroperoxides of the geometrical isomers: trans-10, cis-12 (2), cis-9, trans-11 (3), trans-10, trans-12 (4), and trans-9, trans-11 (5)-octadecadienoates plus two nonconjugated hydroperoxides. The higher cis/trans to trans/trans (ct/tt) of geometrical isomers (2 + 3//4 + 5) compared to ct/tt from known thermal free-radical peroxidations (Type 1) indicate that singlet oxygen (Type 2) oxidation occurs in reactions sensitized by 6 or 7. Kinetic studies by oxygen uptake are reported on oxidations of hydrocarbons 1-phenyl-2-methylpropene,8, and trans-stilbene,9, sensitized by the quinone, 6, or by a dye, Rose Bengal. Quenching studies imply singlet oxygen reactions. Milled wood lignin undergoes self-initiated photo-oxidation in water, and oxygen uptake was quenched by sodium azide. Cellobiose, a cellulose model, undergoes sensitized photo-oxidation using model quinone, 6, in a mixture of tert-butyl alcohol and water or using the sensitizers benzophenone or the lignin model, 7, delivered on a solid support, silica gel, and these oxidations were quenched with sodium azide. These results implicate singlet oxygen in the photo-yellowing of high lignin content wood pulps.Key words: lignin models, ortho-quinone, photo-oxidation, singlet oxygen, lignin, cellobiose.

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