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Tuesday, August 11, 2020 | History

3 edition of Kinetics of a photosensitized reaction of substituted polystyrenes found in the catalog.

Kinetics of a photosensitized reaction of substituted polystyrenes

C. Sreekumar

Kinetics of a photosensitized reaction of substituted polystyrenes

electrochemical reduction of 9, 12-diphensuccindan derivatives

by C. Sreekumar

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  • 2 Currently reading

Published .
Written in English


Edition Notes

Statementby C. Sreekumar.
Classifications
LC ClassificationsMicrofilm 80811
The Physical Object
FormatMicroform
Paginationvii, 148 leaves
Number of Pages148
ID Numbers
Open LibraryOL3069405M
LC Control Number82167283

@article{osti_, title = {Kinetics of photosensitized electron transport across a membrane boundary}, author = {Wamser, C C and Otvos, J W and Calvin, M}, abstractNote = {A generalized system is described which accomplishes a photosensitized oxidation and reduction and the separation of the resultant oxidized and reduced species across a membrane boundary. A reaction mechanism is proposed, initiated by electron transfer from the quencher to the excited photosensitizer. This type of photo-induced reaction in the sea-surface microlayer has the potential to trigger the production of many oxidized species, including halogen atoms, .

Mechanisms of photosensitized reactions. Here 3 S* is a photosensitizer in an excited triplet state, 3 SH* is another representation of the same photosensitizer, but with a potentially transferable proton indicated, X is a target molecule, and XH + is a substrate or solvent molecule that has accepted a proton. The reporter groups are aryl-substituted cyclopropanes at the position of the radical center in the incipient product, and the initial ring-opening reaction gives an aryl-substituted.

  This title addresses the latest developments in the field, covering the major advances that have occurred over the past five years in the polymerization and structure of new generation polystyrenes that are broadening its scope of application. It covers the advent of branched polystyrenes, syndiotactic polystyrene, high-molecular weight general purpose PS, styrenic Reviews: 1. A practical approach to chemical reaction kineticsfrom basic concepts to laboratory methodsfeaturing numerous real-world examples and case studies This book focuses on fundamental aspects of reaction kinetics with an emphasis on mathematical methods for analyzing experimental data and interpreting results. It describes basic concepts of reaction kinetics, parameters for measuring the progress.


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Kinetics of a photosensitized reaction of substituted polystyrenes by C. Sreekumar Download PDF EPUB FB2

Singlet oxygen generated via photosensitized reaction decomposes less-fluorescent folic acid and MTX, leading to the formation of a strongly fluorescent pteridine compound in D 2 O (Fig. 14).This method can be applied to determine the Φ Δ of photosensitizers absorbing visible light.

One of the most important applications of the photosensitized reaction is PDT, in which a water-soluble. The inhibition of photo‐oxidation by N ‐ 3 suggests that the reaction occurs via a singlet oxygen mechanism. The polychlorophenols give different proportions of reaction with and quenching of singlet oxygen.

The total rate constant for the process is in the order of 10 8 to l0 9 M ‐1 s ‐1. A charge transfer mechanism for quenching of Cited by: The reaction rate of Fe 2+ with Ru(bipy) 3 3+ is probably the slowest known between primary photoproducts (22) in homogeneous solutions.

Photochemical storage will become a reality only when reactions of the initial photoproducts that lead to a kinetically stable system can compete successfully with the back reactions. Kinetics of singlet oxygen luminescence follow (1) I(t)=I 0 ∫ 0 t e −k 1 t′ e −k 2 (t−t′) d t′ where I(t) is the singlet oxygen luminescence intensity in time t after the excitation pulse, I 0 is a proportional constant, k 1 and k 2 are reciprocal values of the singlet oxygen population and depopulation time constants τ 1 and τ 2, and t′ is an integration by: Comparing the kinetics parameters with those from the reactions in degassed water, we found a much faster reaction time for the latter with a TOF of ×10 −2 min −1 and a half‐life of h.

In sharp contrast, reactions performed in toluene/ G4 as gel medium were slowed down to TOF and half‐life values of of ×10 −2 min −1 and Cited by: 1. In a typical photosensitized reaction, as in the photodecomposition of ethylene to acetylene and hydrogen, a mixture of mercury vapour and ethylene is irradiated with a mercury mercury atoms absorb the light energy, there being a suitable electronic transition in the atom that corresponds to the energy of the incident light.

Another photosensitized reaction is the decomposition of oxalic acid in presence of uranyl sulphate. UO 2 2+ + hv → UO 2 2+* UO 2 2+* + (COOH) 2 → UO 2 2+ + CO 2 + CO + H 2 O. The uranyl ion acts as a photosensitizer. The decomposition of ozone in ordinary light by a trace of chlorine is an example of photosensitized reaction.

Photosensitized oxidation is a process in which a compound (which may not absorb light itself) is oxidized in the presence of light, oxygen and a light-absorbing molecule called a photo-sensitizer (Gollnick, ; Foote, ; Frimer, ).

Thermal decomposition kinetics of poly(p-substituted styrene)s was examined in nitrogen atmosphere. Five different heating rates were applied to the samples and as heating rate increased, the degradation shifted to higher temperatures accompanied with an increase in the rate of weight loss.

Deprotection of oximes to their corresponding carbonyl compounds through the use of photosensitized electron-transfer reactions proceeds in reasonable to good yields. Better yields are obtained in nonpolar solvents and when triplet sensitizers are used. Preliminary mechanistic studies suggest the involvement of an iminoxyl radical.

2-Mercaptobenzothiazole (2MBT) is a more toxic as compare to the benzothiazole (BT) and the photosensitized reaction Of 2MBT with methylene blue (MB) in. Kinetics of reactions of chlorine dioxide (OClO) in water—I. Rate constants for inorganic and organic compounds.

Water Research28 (1), DOI: /(94)X. Paul G. Tratnyek, Jürg Hoigné. Kinetics of reactions of chlorine dioxide (OCIO) in water—II. In the case of para-substituted polystyrenes a good linear dependence was found between Tmax on the thermogravimetry curve and the Hammett constants of the substituents (Tmax =– σx).

If we assume that the degradation process can be described by the classical equation dte/dt = k(1 - oc)m where k and n are analogous to a rate constant and an order of reaction, we can obtain k by Kinetics of partially para-brominated polystyrenes 77 1,0 0,8 0,6 0,4 0,2 0,0 Bouster et al Photosensitized reaction has been done for the decomposition of organic contaminate and has been combined with the adsorbent (clay minerals) as an "adsorbent and reaction" approach (Sasai et al.

The kinetics of the addition of anthracene to living polystyrene has been investigated. Two types of polymers have been studied: those possessing one active end per chain and others endowed with two active ends in each polymeric molecule.

The addition is rapid (rate constant of. Photosensitized degradation kinetics of trace halogenated contaminants in natural waters using membrane introduction mass spectrometry as an in situ reaction monitor D.

Letourneau, C. Gill and E. Krogh, Photochem. The photosensitized oxidation of single bilayer vesicles of egg-yolk lecithin by singlet oxygen is investigated. The isotopic enhanced lifetime of singlet oxygen in heavy water, and the inhibitory effect of azide ions, are both used to examine the O 2 (1 Δ g) diffusion rate of photo-oxidation of unsaturated fatty acid is shown to be strongly dependent on the precise.

A Mechanistic Description of the Sensitized N-Substituted Maleimide Initiated Photopolymerization of an Acrylate Monomer. Photopolymerization kinetics of dimethacrylates using the camphorquinone/amine initiator system.

Toshihiko Hoshi, Isao Ono, Jun Okubo. Photochemical reaction of 2,2′-pyridil — photoreduction to trans-enediol. The effett of medium on cidnp kinetics in geminate recombination of biradicals. Experiment and calculation. Lifetimes of biradicals produced in the Norrish type I reaction of methyl-substituted 2-tetralones.

Journal of Photochemistry and Photobiology A: Chemistry Cidnp study on porphyrin-photosensitized reactions with phenol and quinone. Photosensitization is a condition caused by the accumulation of a photodynamic agent in the skin that sensitizes it to ultraviolet radiation (Fowler ).Exposure of nonpigmented skin to UV radiation (e.g., the sun) results in dermatonecrosis.

Three mechanisms of photosensitization have been described in animals, but the one germane to this discussion is type III, or hepatogenous.One reason for the importance of kinetics is that it provides evidence for the mechanisms of chemical processes.

Besides being of intrinsic scientific interest, knowledge of reaction mechanisms is of practical use in deciding what is the most effective way of causing a reaction to occur. Many commercial processes can take place by alternative reaction paths, and knowledge of the mechanisms.The kinetics of reactions of substituted 1,phenanthroline complexes of iron(III) with octacyanomolibdate(IV) and hexacyanoferrate(II) in the presence of sodium dodecyl sulphate.

Inorganica Chimica Acta46, LL