Auto-redox reaction

The biological mechanism of action is helieved to involve the production of superoxides near the DNA strand, resulting in DNA backbone cleavage and cell apoptosis. The actual mechanism is not yet known, but is believed to proceed from the reduction of molecular oxygen into superoxide via an unusual auto-redox reaction on a hydroxyquinone moiety of the compound following. There is also some speculation the compound becomes activated into its reactive oxazolidine form. 

The polymerization can terminate when the free-radical terminal C of a long chain forms a bond with the terminal C of another long chain (combination), RC- + CR —- RC—CR. Termination may also occur when the terminal free-radical C s of two long chains disproportionate, in a sort of auto-redox reaction. One C picks off an H from the C of the other chain, to give an alkane at one chain end and an alkene group at the other chain end ... 

This work shows that oxygen-free sulfite in lime/limestone slurries, exposed to sulfur dioxide, slowly decomposes under process conditions. In fact, auto-redox reactions of sulfur oxyacids can occur in all coal desulfurization systems, including coal-gasification systems and impurities present in commercial flue gas systems are capable of catalyzing the reaction under process conditions. Our experiments indicate that any large-scale coal utilization will depend on appropriate control of the autoredox reactions of sulfur species. 

Solutions of Sodium and Potassium Sulfite and Bisulfite. Oxygen free, pure sulfite and bisulfite solution containing sodium or potassium ions are stable for more than a year at room temperature. However, at 100°C or above, the sulfate spectrum can be observed already after a few days. Elemental sulfur does not immediately appear. Sometimes, at intermediate and high pH, thiosulfate can be observed in a few experiments. The appearance of these species indicates that they are intermediates in the auto-redox reaction Equations I-III, or that they are formed in a secondary reaction of sulfur (IV) with the product elemental sulfur. The latter reactions are already known. They occur during the degradation of elemental sulfur... 

He have also studied the effect of metal ions, and found that the heavy metals, such as Se, Mn, Cr, and V do not only catalyze the oxidation by oxygen from air, but also strongly catalyze the oxygen-free auto-redox reaction described above. 

Our experiments indicate that any large-scale coal utiliti-zation will depend on appropriate control of the auto-redox reactions of sulfur species. 

While it is an effective process, the large amount of steel. Inconel, and sludge causes much of the hydrogen peroxide to decompose by an auto redox reaction ... 

An important consideration for auto manufacturers today is fuel economy and pollution reduction. Fuel cells represent one option to achieve these goals. Like a battery, a fuel cell produces electricity from a redox reaction. Unlike a battery, a fuel cell can generate electric current indefinitely because it oxidizes a continuous stream of fuel from an outside source. 

Thus, the decomposition of sulfite occurs at lower temperature and far quicker than generally assumed, under conditions well within the temperature range of many desulfurization processes. The reaction involves the auto-redox decomposition of sulfur (IV). Depending on the pH of the system, the overall reaction can be summarized as shown in Equations I-III. 

Atom-transfer radical cyclization (ATRC) is an atom-economical method for the formation of cyclic compounds, which proceeds under mild conditions and exhibits broad functional group tolerance. Okamura and Onitsuka described a planar-chiral Cp-Ru complex 124-catalyzed asymmetric auto-tandem allylic amidation/ATRC reaction in 2013. This protocol proceeds highly regio, diastereo, and enantioselec-tively to construct optically active y-lactams from readily available substrates in a one-pot manner (Scheme 2.32). In this process, a characteristic redox property of ruthenium complexes would work expediently in different types of catalyzes involving mechanistically distinct allylic substitutions (Ru /Ru ) and atom-transfer radical cyclizations (Ru /Ru ), thus leading to the present asymmetric auto-tandem reaction [48]. 

Copper(ll) acetate performs a double role activation of the triacyl methane group by coordination and production of the reactive triacylmethyl radical by a coupled redox reaction. The proposed mechanism is supported by the fact that 274 is present in the auto-oxidation reaction mixture of hexahydrocolupulone, while compounds 275-279 are absent. Auto-oxidation occurs indeed at the ring carbon atom C-4 (see 13.1.2.). The radicals are in this case produced within the 1,3-dicarbonyl system in the ring, whereby only 274 can be formed in an analogous way as described before (pathway B). 

The synthesis started from 6-nitrocyclohex-2-enone 249 to provide the catechol 250 by two kinds of methodologies including the hydrogen transfer reaction followed by the auto-redox-catalytic reaction. Oxadecalin 247 was synthesized from glycosyl cyanide 246. The [3+3] cycloadduct was afforded in one pot by treatment of ketone 247 with AI2O3 in situ to form the enone 248, and then reacted with catechol 250 in the presence of boron trifluoride. The target product ep/-cochlioquinone A 252 was afforded after a series of regular reactions [110]. 

The first reaction, conversion of ethylene to acetaldehyde, involves organometallic and redox chemistry of palladium. Oxidation of cyclohexane and /7-xylene by air, on the other hand, is a chain reaction of organic radicals. In these reactions, soluble cobalt and manganese compounds catalyze the initiation steps. Reactions such as these, where the organic substrates are directly oxidized by air or dioxygen, are often called auto-oxidation reactions. 

On the basis of their redox thermodynamics and reaction chemistry with 02"- in aprotic media, ascorbic acid S and some catechols may be subject to an (O2 -)-catalyzed auto-oxidation to dehydroascorbic acid and o-quinones, respectively. 

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