Oxidants Other Than Oxygen

Reactions between Organic Compounds and Oxidizers Other Than Oxygen... 

A review by Schuchardt et al. thoroughly analyses the various catalytic systems reported in the literature up to 2000, both homogeneous and heterogeneous ones, and those that use oxidants other than oxygen [e.g., HP or t-butyl hydroperoxide (f-BuOOH)[ [2c[. The mechanism involves the formation of cyclohexanol via the cyclohexyl radical and cyclohexyl hydroperoxide. According to the Haber-Weiss mechanism, cyclohexyl hydroperoxide decomposes into alkoxy and alkyloxy radicals (Section 7.2.1). Cyclohexanol is finally oxidized to cyclohexanone. A similar mechanism may occur at the a-C, affording 1,2-cyclohexanedione, which is finally cleaved to AA. Oxidation of the intermediately formed cyclohexanone to AA then occurs through a mechanism similar to that illustrated in Scheme 7.5. 

Oxidation by Oxidants other than Oxygen. Methane can be reacted with chlorine, for example, to produce chlorinated hydrocarbons which can be converted to olefins by subsequent reaction with oxygen. 

Anyone who has worked with the catecholamines knows how readily they are air-oxidized. Indeed, a variety of oxidants other than oxygen will rapidly react with catecholamines (CAs) in the following fashion ... 

Gas produced by oxidizer other than that formed by reaction of oxygen and fuel components. 

Purity. Electrolytic copper is one of the purest of the materials of commerce. The average copper content of ETP copper, for instance, is over 99.95%, and even the highest level of impurities other than oxygen are found only to the extent of 15—30 ppm. Up to 0.05% oxygen is present in the form of copper(I) oxide. Even at these low impurity levels, properties of interest to fabricators are affected in varying degree. 

Under aqueous conditions, flavonoids and their glycosides will also reduce oxidants other than peroxyl radicals and may have a role in protecting membranal systems against pro-oxidants such as metal ions and activated oxygen species in the aqueous phase. Rate constants for reduction of superoxide anion show flavonoids to be more efficient than the water-soluble vitamin E analogue trolox (Jovanovic et al, 1994), see Table 16.1. 

According to the results of Ben Taarit and co-workers (76) and Neikam (77) Ce(III) Y zeolites will not form anthracene cation radicals but upon oxidation to Ce(IV) the radicals are readily formed. This experiment suggests that one role of oxygen during calcination may be to oxidize certain cations. The surface may be oxidized by molecules other than oxygen since the chlorination of 7-alumina by carbon tetrachloride considerably increases the sites responsible for the acceptor character. These sites, which oxidize perylene into the paramagnetic radical ion, have been attributed to biocoordinated positive aluminum atoms (78). 

Laboratory studies of effects of photochemical oxidants other than ozone—e.g., PAN, peroxybenzoylnitrate, atomic oxygen, excited molecular oxygen, Oj( A ), and hydroperoxy and hydroxyl radicals—on specific materials should be conducted. 

Many metals are relatively inert they don t combine chemically with other substances as easily as non-metals do. For example, iron rusts and copper oxidizes. The green color of copper domes comes from a thin layer of a copper carbonate. But neither iron nor copper spontaneously combines with elements other than oxygen that are found in the natural environment. Otherwise, we would not have copper coins,... 

Olefin epoxidation is another synthetic route of great interest that has been the object of several investigations, not only in multiphase reaction systems but also with oxidants other than molecular oxygen, such as inorganic and organic peroxides [55-57]. 

Our hypothesis is based on the observation that the photooxidation upon direct excitation of F yields G as well as a hydroxylated sulfone, too (28). Again, this reaction must involve oxidants other than singlet oxygen, for no reaction has been observed between the latter and ground state 10-methyl-phenothiazine-5-oxide (F). 

The gas other than oxygen which has been most extensively studied as a reactant with solids is, of course, hydrogen and the first and longest section of this chapter is therefore devoted to gaseous reduction. The theory of this topic, especially in relation to iron oxides [1, 2], well exemplifies much of the general theory of solid state kinetics as reviewed by one of us [3] in an earlier volume of this series. For the present purpose, therefore, we have reworked the necessary discussion of kinetic equations into the specific topic of Sect. 2. 

A search for organisms with novel metabolic and bioenergetic pathways, particularly pathways involved in carbon dioxide and carbon monoxide reduction and methane oxidation coupled with electron acceptors other than oxygen ... 

All plants depend on nitrate reductase to accomplish the seemingly trivial reaction of nitrate reduction to nitrite, often the first step of nitrogen assimilation into compounds required for growth (5, 22). Many bacteria use molybdenum or tungsten enzymes in anaerobic respiration where the terminal electron acceptor is a reducible molecule other than oxygen, such as nitrate (2, 50), polysulfide (51), trimethylamine oxide (33, 52) or dimethyl sulfoxide (DMSO) (2, 29, 30). 

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