Oxidation processes oxygen

In the oxidation process, oxygen and chlorine, the positive product is in the Group oxidation number, for the Main Group elements whereas for the reduction process, the negative product is 8 — GON, where the... 

Incidentally, numerous petroleum products, particularly those coming from conversion processes, are unstable with respect to oxidation and oxygen analysis is meaningful only if great precautions are taken during sample withdrawal and storage. 

White phosphorus is very reactive. It has an appreciable vapour pressure at room temperature and inflames in dry air at about 320 K or at even lower temperatures if finely divided. In air at room temperature it emits a faint green light called phosphorescence the reaction occurring is a complex oxidation process, but this happens only at certain partial pressures of oxygen. It is necessary, therefore, to store white phosphorus under water, unlike the less reactive red and black allotropes which do not react with air at room temperature. Both red and black phosphorus burn to form oxides when heated in air, the red form igniting at temperatures exceeding 600 K,... 

This oxidation process for olefins has been exploited commercially principally for the production of acetaldehyde, but the reaction can also be apphed to the production of acetone from propylene and methyl ethyl ketone [78-93-3] from butenes (87,88). Careflil control of the potential of the catalyst with the oxygen stream in the regenerator minimises the formation of chloroketones (94). Vinyl acetate can also be produced commercially by a variation of this reaction (96,97). 

Oxidative processes can also be used to prepare DMF. For example, it can be produced from tetraoxane (a source of formaldehyde (qv)), oxygen, and dimethylamine over Pd—AI2O2 (24) or from trimethylamine and oxygen ia the presence of a metal haUde catalyst (25). 

Benzophenone Process. Benzophenone, (CgH5 )2C=0, reacts with ammonia to form diphenylmethanimine, (CgHg )2C=NH. In the presence of copper catalysts, this is oxidized with oxygen to benzophenone azine, (CgHg )2C=N—N=C(CgHg The formation of the imine and its... 

Sihcon dioxide layers can be formed using any of several techniques, including thermal oxidation of siUcon, wet anodization, CVD, or plasma oxidation. Thermal oxidation is the dominant procedure used in IC fabrication. The oxidation process selected depends on the thickness and properties of the desired oxide layer. Thin oxides are formed in dry oxygen, whereas thick (>0.5 jim) oxide layers are formed in a water vapor atmosphere (13). 

Ura.nium, The hydrometallurgical treatment of uranium ores is a concentration and purification process. Typical ore grade is 0.1—0.5% U Og, and pregnant solutions contain ca 1 kg/m of U Og. The dissolution requires the presence of an oxidant, either oxygen or a ferric salt. 

The anhydride can be made by the Hquid-phase oxidation of acenaphthene [83-32-9] with chromic acid in aqueous sulfuric acid or acetic acid (93). A postoxidation of the cmde oxidation product with hydrogen peroxide or an alkaU hypochlorite is advantageous (94). An alternative Hquid-phase oxidation process involves the reaction of acenaphthene, molten or in alkanoic acid solvent, with oxygen or acid at ca 70—200°C in the presence of Mn resinate or stearate or Co or Mn salts and a bromide. Addition of an aHphatic anhydride accelerates the oxidation (95). 

In the first step, propylene is introduced at 10—40°C into nitric acid, the concentration of which is kept at 50—75 wt % and molar ratio to propylene at 0.01—0.5, and converted into a-nitratolactic acid and lactic acid. a-Nitratolactic acid is oxidized by oxygen in the second step in the presence of a catalyst at 45—100°C to produce oxahc acid dihydrate. The overall yield based on propylene is greater than 90% and the conversion of propylene, 77.5%. The outhne of the process is shown in Figure 2. The RhcJ)ne-Poulenc process can be characterized by the coproduction of lactic acid. 

In the presence of oxygen (air), the thermal decomposition of amphiboles is associated with an oxidation of divalent iron to trivalent iron, which may lead to an increase in the sample weight the oxidation process also induces an obvious color alteration, the fibers acquire the characteristic ferric oxide... 

Copper is one of the twenty-seven elements known to be essential to humans (69—72) (see Mineral nutrients). The daily recommended requirement for humans is 2.5—5.0 mg (73). Copper is probably second only to iron as an oxidation catalyst and oxygen carrier in humans (74). It is present in many proteins, such as hemocyanin [9013-32-3] galactose oxidase [9028-79-9] ceruloplasmin [9031 -37-2] dopamine -hydroxylase, monoamine oxidase [9001-66-5] superoxide dismutase [9054-89-17, and phenolase (75,76). Copper aids in photosynthesis and other oxidative processes in plants. 

---