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Showing 1 to 20 of 25 for “"Radical anion"”.
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Radical anion rearrangements. aryl cyclopropyl ketyl anions
… can be ascribed to the intermediacy of a ketyl anion. Through a detailed examination of the decay of electrolytically generated aryl cyclopropyl] ketyl anions, we have shown that the assumptions made in the use of these substrates as SET probes are not necessarily valid. Using derivative cyclic …
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The elucidation of single electron transfer (SET) mechanisms in the reactions of nucleophiles with carbonyl compounds
The chemistry of the radical anion generated from 1,I-dimethyl-5,7-di-tbutylspiro[ 2,5]octa-4,7-dien-6-one (<b>20</b>) was studied electrochemically using cyclic and linear sweep voltammetry (CV, LSV). The reduction potential of <b>20</b> was estimated to be -2.5 V VS. 0.1 M Ag⁺/Ag, similar to the …
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Reductive and oxidative dissociative electron transfers: transition between the concerted and stepwise mechanistic pathways
… are presented. In cases where the ring-closed radical anion generated by reduction of the epoxyketones is resonance stabilized (aromatic epoxyketones) the mechanism proceeds in a stepwise fashion, where the electron transfer and bond breaking reactions occur in sequential, discrete steps. On …
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Use of the Cyclopropylcarbinyl - Allylcarbinyl Rearrangement as a Probe of the Thiophilic Addition Reaction Mechanism
… ring openings independently characterizable as anionic or radical anionic as required for the successful diagnostic use of the cyclopropylcarbinyl-allylcarbinyl rearrangement. Cyclic voltammetry was examined as a technique to generate and characterize electrochemically the chemistry of the …
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Part I. Studies of the substitution and formation reactions of rhenium carbonyl o-semiquinone compounds. Part II. Molecular mechanics studies of the steric interactions in chromium pentacarbonyl phosphine compounds
… from the sodium semiquinone radical anion and Re(CO)$\sb5$Cl is reported. The substitution kinetics of (3,5-di-t-butyl-1,2-benzosemiquinone)Re(CO)$\sb4$ with P(n-Bu)$\sb3$ was studied by stopped-flow methods. The observed kinetics data shows considerable variability, both …
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Birch reduction of benzenesulfonamide and benzenephosphonic acid
… one electron to the aromatic nucleus to give a radical anion or a transfer of two electrons to form a dianion. (2,3,4) Either intermediate would then be a very strong base and would react promptly with proton donors such as alcohols, water, or ammonium salts. Figure 2 [see PDF] </p>
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The Gas-Phase Oxidation of Cationic Bioanalytes via Ion/Ion Reactions
… ion/ion reactions with periodate and persulfate anions. Methionine and tryptophan residues in simple polypeptides are selectively oxidized upon ion/ion reactions with periodate anion. The oxidative labeling of disulfide bonds is performed via ion/ion reactions and is used to identify …
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Mechanistic and preparative studies of Electrochemical Deoxygenation and Debromination
… step involves the reversible formation of a radical anion, followed by fragmentation to 3,5- bis(trifluoromethyl)benzoate and the corresponding alkyl radical. Subsequent electrochemical reduction of the radical would be expected to form a carbanion. Protonation, presumably by trace water …
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Mechanistic insights on the merits and limitations of advanced treatment processes for removal of contaminants of emerging concern
… key reactive oxygen species (ROS) i.e. hydroxyl radical (•OH) and superoxide radical anion (O2•-) in degrading PFAS with some studies demonstrating their effectiveness while others claiming the contrary. This dissertation aims to provide mechanistic insights into the treatment of PFAS and other …
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Rearrangements of Radical Anions Generated from Cyclopropyl Ketones
… assumption in such studies is that if a "radical" species is produced, it will undergo ring opening. We have found that there are two important factors to consider in the design of SET probes: 1) ring strain, the thermodynamic driving force for the rearrangement, and 2) resonance energy, …
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The Chemistry of Aroyl Azides in Piperidine- and Steroid-Separated Bichromophoric System: Photoinduced Long-Distance Intramolecular Electron Transfer Reactions
… intermediate states. The aryl amine radical cations were detected by pulsed laser spectroscopy and the highly reactive aroyl azide radical anions were identified by the results of steady-state photolysis. In acetonitrile and in methyl alcohol solution, the photoexcited aryl amine …
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Free radical reactions of allylic and propargylic derivatives
<p>Addition of tert-butyl radical, generated from t-BuHgCl, to allyl or propargyl derivatives forms adduct radicals which can undergo [beta]-elimination with substituents such as halogen, PhS, PhSO[subscript]2 to form the alkyl-substituted propene or allene and an eliminated radical which …
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Spectroscopy, Electrochemistry and Photochemistry of Phenylazonaphthalene Dyes
… with photoinitiator generated 2-hydroxy-2-propyl radicals to study reductive fading. Time-resolved studies were carried out on OH-Span:photoinitiator solutions and rate constants for electron transfer to produce the dye radical anion and subsequent disproportionation were found to be 6.00 * 10^9 …
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Pioneering investigations into organometallic electrochemistry
… showing remarkably facile reduction to a radical anion, and further reduction to a dianion. Simulation of the cyclic voltammetry recorded for these compounds yielded optimised values of formal potentials, E0, and electron transfer rate constants, k0. In chapter 4, the synthesis and …
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Development and Construction of a new Photoelectron Imaging Spectrometer for Studying the Spectroscopy and Ultrafast Dynamics of Molecular Anions
… spectroscopy and ultrafast dynamics of molecular anions in the gas phase. The new instrument incorporates: an electrospray ionisation source, which is capable of generating a vast class of molecular anions; a Wiley-McLaren time-of-flight mass spectrometer; and a compact photoelectron imaging …
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Physiological, biochemical and molecular aspects of induced resistance in maize against Bipolaris maydis infection using a zinc-polyphenolic compound and silicon
… (MDA), hydrogen peroxide (H2O2), and radical anion superoxide (O2●-) compared to control plants. During the infection by B. maydis, IR stimulus-sprayed plants showed increased concentrations of sucrose and starch and greater activities of catalase (CAT), glutathione reductase (GR), and …
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Towards electrochemical diagnostics of biochemical free radical species in aqueous microliter volumes
Reactive oxygen species (ROS) are free radicals often implicated in disease states. In probing related enzyme processes, reactant consumption must be minimized. Levitated drops show potential as microreactors where radicals are present as reactants or products. Solid/liquid interfaces are absent or …
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Mechanistic Studies of the Structure-Photostability Relationship of Organic Conjugated Polymers
… that lead to photodegradation of CPs, the radical mechanism is initiate by generation of superoxide radical anion and the other mechanism is initiated by singlet oxygen. C8-diCN-PPV has a lower LUMO level compared to RO-diCN-PPV, yet photodegrades more quickly. RO-diCN-PPV and C8-diCN-PPV …
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Photodegradation of peptides and proteins by near UV and visible light
… the light-induced formation of H2O2, hydroxyl radicals (●OH), carbon dioxide radical anion (●CO2-), and formaldehyde was demonstrated. Several products were observed, including the formation of novel products on Tyr. The yields of oxidation products in acetate and succinate formulations were …
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Generation and observation of reactive intermediates in the gas phase and condensed media
… N-oxide. The chemistry of peroxide dianion, in the form of the encapsulated complex [O₂[subset]mBDCA- 5t-H₆]²-, has been explored in nonaqueous media. In particular, [O₂[subset]mBDCA-5t-H₆]²- was demonstrated to react with CO gas at 40 °C over the course of several hours to furnish the …
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