Peroxide process

The reaction pathway involves the formation of an intermediate that is able to oxidize ammonia to a hydrazine derivative. The methyl ethyl ketazine is insoluble in the reaction mixture and is separated by decantation and is then purified by distillation. The purified ketazine is hydrolyzed under pressure (0.8 to 10 MPa) to give concentrated aqueous hydrazine and MEK that is recycled132. 

The Peroxide process has many advantages compared to other processes no salt by-product, high yields, low energy consumption, low molar excess and no aqueous effluent treatment132. 

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High Peroxide Process. An alternative to maximizing selectivity to KA in the cyclohexane oxidation step is a process which seeks to maximize cyclohexyUiydroperoxide, also called P or CHHP. This peroxide is one of the first intermediates produced in the oxidation of cyclohexane. It is produced when a cyclohexyl radical reacts with an oxygen molecule (78) to form the cyclohexyUiydroperoxy radical. This radical can extract a hydrogen atom from a cyclohexane molecule, to produce CHHP and another cyclohexyl radical, which extends the free-radical reaction chain. 

ARCO has developed a coproduct process which produces KA along with propylene oxide [75-56-9] (95—97). Cyclohexane is oxidized as in the high peroxide process to maximize the quantity of CHHP. The reactor effluent then is concentrated to about 20% CHHP by distilling off unreacted cyclohexane and cosolvent tert-huty alcohol [75-65-0]. This concentrate then is contacted with propylene [115-07-1] in another reactor in which the propylene is epoxidized with CHHP to form propylene oxide and KA. A molybdenum catalyst is employed. The product ratio is about 2.5 kg of KA pet kilogram of propylene oxide. 

Propylene oxide [75-56-9] is manufactured by either the chlorohydrin process or the peroxidation (coproduct) process. In the chlorohydrin process, chlorine, propylene, and water are combined to make propylene chlorohydrin, which then reacts with inorganic base to yield the oxide. The peroxidation process converts either isobutane or ethylbenzene direcdy to an alkyl hydroperoxide which then reacts with propylene to make propylene oxide, and /-butyl alcohol or methylbenzyl alcohol, respectively. Table 1 Hsts producers of propylene glycols in the United States. 

Comparison to the Raschig Process. The economics of this peroxide process in comparison to the Raschig or hypochlorite—ketazine processes depend on the relative costs of chlorine, caustic, and hydrogen peroxide. An inexpensive source of peroxide would make this process attractive. Its energy consumption could be somewhat less, because the ketazine in the peroxide process is recovered by decantation rather than by distillation as in the hypcochlorite process. A big advantage of the peroxide process is the elimination of sodium chloride as a by-product this is important where salt discharge is an environmental concern. In addition to Elf Atochem, Mitsubishi Gas (Japan) uses a peroxide process. 

The cmde product from any hydrogen peroxide process can be used as such, but commercial grades are further purified, concentrated, and stabili2ed. 

High pressure Hquid chromatography (qv) (138) and coulometry can be used to detect and quantify anthraquinones and thek derivatives in a hydrogen peroxide process working solution. 

Following the action of extraordinary stimulants (hypoxic hypoxia, hypoxia + hyperoxia, hypodynamia + hyperthermia), animals demonstrate an accumulation of malonic dialdehyde with a simultaneous fall of antiradical activity of the liver tissue. A preliminary introduction to rats of acetylene amine 3,4,5-tris(morpho-linopropynyl)-l-methylpyrazole 103 and also of tocopherol antioxidant and gutumine antihypoxant averts activation of the lipid peroxidation processes. The inhibition of peroxidation with this agent is mediated by stabilization of ly-zosomal and mitochondrial membranes. Unsaturated amines prevent destruction of the organelle membranes provoked by UV irradiation and incubation at 37°C (pH4.7)(78MIl). 

Sandman, G. Boger, P. (1980). Copper mediated lipid peroxidation processes in photosynthetic membranes. Plant Physiology, 66, 797-800. 

The applications of high-resolution H-NMR spectroscopy to the analysis of products arising from the lipid peroxidation process are described in Section 7. 

Although MDA, an end-product of the lipid peroxidation process is thought to be the major contributor to the chromogen, it has now become clear that a number of other species such as sucrose, urea, proteins and other aldehydes also react with TBA to produce chromogens that absorb at a wavelength near to 532 nm (Marshall et al., 1985). Moreover, it should also be noted that since only a small proportion (1-2%) of the lipid peroxidation... 

Esterbauer et cil. (1992) have studied the in vitro effects of copper on LDL oxidation and have shown that there are three distinct stages in this process. In the first part of the reaction, the rate of oxidation is low and this period is often referred to as the lag phase the lag phase is apparently dependent on the endogenous antioxidant content of the LDL, the lipid hydroperoxide content of the LDL particle and the fatty acid composition. In the second or propagation phase of the reaction, the rate of oxidation is much faster and independent of the initial antioxidant status of the LDL molecule. Ultimately, the termination reactions predominate and suppress the peroxidation process. The extensive studies of Esterbauer et al. have demonstrated the relative importance of the endogenous antioxidants within the LDL molecule in protecting it from oxidative modification. 

We have already stressed the potential importance of lipid-rich membranes in the skin as potential targets for ROS-induced damage and ageing of human skin is morphologically identical to changes found by peroxidative processes (Serri et al., 1977). The involvement of AA metabolites in skin disease, and in particular psoriasis, has been the subject of much recent interest. Studies have included topical and intradermal administrations of AA metabolites, and assay of such products in clinical specimens. Results show that concentration of AA, 12-hydroxy-eicosatetraenoic acid (12-HETE), PG and leu-kotrienes are increased in psoriatic lesions (Hammarstrom etal., 1975 Camp etal., 1983 Brain etal., 1984 Duell et al., 1988) and also that full-thickness epidermis from normal and diseased skin has the enzymatic capacity to convert AA to some of the same metabolites (Hammarstrom etal., 1975, 1979 Camp etal., 1983 Brain etal., 1984 Ziboh et al., 1984 DueU et al., 1988). The biological effect of both 12-HETE and leukotrienes was confirmed by both topical application and intradermal injection, which caused epidermal inflammation and... 

Propylene oxide (PO) is an important intermediate in the manufacture of a wide range of valuable products propylene glycol, ethers, isopropanolamines, and various propoxylated products for polyurethanes (1). The current processes for the large scale synthesis of PO include (i) the chlorohydrin process and (ii) the peroxide process (1, 2). 

The disadvantage of the chlorohydrin process is the use of toxic, corrosive, and expensive chlorine the major drawback of the peroxide process is the formation of co-oxidates in larger amounts than the desired PO. The direct epoxidation of propylene using 02 (i.e., partial oxidation of propylene) from air has been recognized as a promising route. 

In addition to the well-known iron effects on peroxidative processes, there are also other mechanisms of iron-initiated free radical damage, one of them, the effect of iron ions on calcium metabolism. It has been shown that an increase in free cytosolic calcium may affect cellular redox balance. Stoyanovsky and Cederbaum [174] showed that in the presence of NADPH or ascorbic acid iron ions induced calcium release from liver microsomes. Calcium release occurred only under aerobic conditions and was inhibited by antioxidants Trolox C, glutathione, and ascorbate. It was suggested that the activation of calcium releasing channels by the redox cycling of iron ions may be an important factor in the stimulation of various hepatic disorders in humans with iron overload. 

Thus, the mechanism of MT antioxidant activity might be connected with the possible antioxidant effect of zinc. Zinc is a nontransition metal and therefore, its participation in redox processes is not really expected. The simplest mechanism of zinc antioxidant activity is the competition with transition metal ions capable of initiating free radical-mediated processes. For example, it has recently been shown [342] that zinc inhibited copper- and iron-initiated liposomal peroxidation but had no effect on peroxidative processes initiated by free radicals and peroxynitrite. These findings contradict the earlier results obtained by Coassin et al. [343] who found no inhibitory effects of zinc on microsomal lipid peroxidation in contrast to the inhibitory effects of manganese and cobalt. Yeomans et al. [344] showed that the zinc-histidine complex is able to inhibit copper-induced LDL oxidation, but the antioxidant effect of this complex obviously depended on histidine and not zinc because zinc sulfate was ineffective. We proposed another mode of possible antioxidant effect of zinc [345], It has been found that Zn and Mg aspartates inhibited oxygen radical production by xanthine oxidase, NADPH oxidase, and human blood leukocytes. The antioxidant effect of these salts supposedly was a consequence of the acceleration of spontaneous superoxide dismutation due to increasing medium acidity. 

Hock Also known as the Hock Lang process, and the cumene peroxidation process. A process for converting isopropyl benzene (cumene) to a mixture of phenol and acetone m-di-isopropyl benzene likewise yields resorcinol, and p-di-isopropyl benzene yields hydro-quinone. The basis of the process is the liquid-phase air oxidation of cumene to cumene hydroperoxide ... 

Hydrogen peroxide processes, for propylene oxide production, 20 806 Hydrogen peroxide stabilizer packages, 14 40... 

Since the key to this sequence is the H02 radical, the aqueous hydrogen peroxide process discussed for NO to N02 conversion in the stack would be an appropriate approach. The S02 forms no corrosive liquid mist in the stack and could be removed by wet scrubbing of the exhaust. 

The overall yield of styrene (the amount of EB that ends up as styrene) via this peroxidation process route is 90%. 

Stefan, M.I. and Bolton, J.R. Mechanism of thedegradationof 1,4-dioxane in dilute aqueous solution using the UV/hydrogen peroxide process, Environ. Sci. Technol, 32(11) 1588-1595,1998. 

The iron ion is highly reactive and readily catalyses oxida-tive/peroxidative processes and interacts with oxygen to form the oxygen free radical (superoxide) that damages cell membranes, proteins and DNA. To prevent such destructive events and still safely deliver oxygen, virtually all iron is maintained tightly bound to the proteins involved... 

Generally the treatment of waste water from alkaline scouring/bleaching (peroxide) processes will require an adjustment of pH and temperature, which is normally made by mixing with wastewater from other treatment steps. When surfactants, complexing agents, and so on,... 

The application of chlorine bleach on the basis of hypochlorite/chlorite for the preparation of cotton/linen results in considerable formation of AOX in the effluents. Such processes should be replaced by bleach processes on the basis of peroxide. To obtain a sufficient degree of whiteness during the bleach, a two-step bleach (peracetic acid/peroxide) process has been proposed in the literature [25-27]. Such processes avoid the formation of chlorinated organic compounds (AOX). 

Hager, D.G. Smith, C.E. The UV-hydrogen peroxide process an emerging technology for groundwater treatment. Paper presented at HazMat West 85, Long Beach, California, 1985. 

Raleigh P (2003) Dow/BASF plan PO unit hydrogen peroxide process offers low CapEx, no by-products. Urethanes Technology, London Herold RJ (1976) US Patent 3941849, 2 Mar 1976... 

The crosslinking efficiency of the peroxide process can be increased for some systems by incorporating small amounts of a comonomer containing vinyl groups into the polymer. This approach is used for polysiloxanes by copolymerization with small amounts of vinyltrimethylsilanol... 

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