Simultaneous oxidation

Addition of an alkali metal oxide as a "network modifier to the "network former causes pH sensitivity, i.e., small amounts of alkali metal induce superficial gel layer formation as a merely local chemical attack and so with limited alkali error larger amounts will result in more pronounced dissolving properties of the glass up to complete dissolution, e.g., water-glass with large amounts of sodium oxide. Simultaneous addition of an alkaline earth metal oxide, however, diminishes the dissolution rate. Substitution of lithium for sodium in pH-sensitive glass markedly reduces the alkali error. 

Zr compounds are also useful as Lewis acids for oxidation and reduction reactions. Cp2ZrH2 or Cp2Zr(0 Pr)2 catalyze the Meerwein-Ponndorf-Verley-type reduction and Oppenauer-type oxidation simultaneously in the presence of an allylic alcohol and benzaldehyde (Scheme 40).170 Zr(C)1 Bu)4 in the presence of excess l-(4-dimethylaminophenyl) ethanol is also an effective catalyst for the Meerwein-Ponndorf-Verley-type reduction.1 1 Similarly, Zr(0R)4 catalyze Oppenauer-type oxidation from benzylic alcohols to aldehydes or ketones in the presence of hydroperoxide.172,173... 

The chain mechanism is complicated when two hydrocarbons are oxidized simultaneously. Russell and Williamson [1,2] performed the first experiments on the co-oxidation of hydrocarbons with ethers. The theory of these reactions is close to that for the reaction of free radical copolymerization [3] and was developed by several researchers [4-9], When one hydrocarbon R H is oxidized in the liquid phase at a sufficiently high dioxygen pressure chain propagation is limited only by one reaction, namely, R OO + R H. For the co-oxidation of two hydrocarbons R1 and R2H, four propagation reactions are important, viz,... 

A process to produce styrene monomer and propylene oxide simultaneously was introduced in 1969. 

The isomeric indolizines 38 and 39 seem to contradict these rules Compared to their dimethine derivatives 30 (n = 1) and 29 (n = 1) potentials are more positive by 0.1 V only and their Ksem s are quite similar. In the cases, however, the reduced form contains an azo group which changes to the less energetic azino group on oxidation, simultaneously transforming the indolizine into a pyri-dinium ring. 

As noted earlier, peroxynitrite is formed with a diffusion-controlled rate from superoxide and nitric oxide (Reaction 10). As both these radicals are ubiquitous species, which present practically in all cells and tissues, peroxynitrite can be the most important species responsible for free radical-mediated damage in biological systems. Moreover, it is now known that NO synthases are capable of producing superoxide and nitric oxide simultaneously (see Chapter 22), greatly increasing the possible rate of peroxynitrite production. In addition, another enzyme xanthine dehydrogenase is also able to produce peroxynitrite in the presence of nitrite... 

In an attempt to overcome the problem of accumulation of the oxidized electron donor, we have incorporated a recyclable surface-active electron donor in DODAC vesicles (12). This electron donor contains a sulfide moiety which dimerizes upon light-induced oxidation. Simultaneously, hydrogen is evolved via vesicle-stabilized, catalyst-coated, colloidal CdS particles. The dimer could be chemically reduced for additional hydrogen formation. Figure 9 is an idealized view of this cyclic process (12). 

Oxidation of Schiff s bases derived from l-phenyl-3-aminopyrazoline gives l-phenyl-3-aroylaminopyrazoles,469 the hetero ring and the arylidene group being oxidized simultaneously. See also Duffin and Kendall.520... 

In 1912 Sprengstoff A. G. Carbonit [17] was granted a patent for a method of preparation of this explosive, consisting in reacting hexanitrodiphenyl sulphide with nitric acid. Since picryl chloride, as the starting material for picryl sulphide was rather expensive, another method of preparation of hexanitrodiphenyl sulphone, via tetranitrodiphenyl sulphide, was also used. The latter was obtained by treating chlorodinitrobenzene with sodium thiosulphate. Then it was nitrated and oxidized simultaneously with nitric acid to hexanitrodiphenyl sulphone ... 

Scaling up the preparation is easily accomplished. It 1s best done by increasing the number of reaction vessels rather than by increasing the reaction volume. For example, 10 g of the cis-diol substrate can be oxidized simultaneously using 2.5 g in each of four 1-L Erlenmeyer flasks as described in the procedure. After 4 days, the reaction mixtures are combined prior to the chloroform extraction and the lactone is isolated. 

Positions C-2 and C-3 can also be oxidized simultaneously. The resulting dicarbonyl derivative is converted to a furanosidic acid unit or directly degraded. Some oxidation of C-6 may also occur, giving rise to chain cleavage at C-4. 

Figure 13 Experimental and predicted profiles of phenol, orttio-dihydroxybenzene, and poro-dihydroxybenzene using KM 1 for (a) unpromoted PC oxidation and (b) Fe-assisted PC oxidation. Simultaneous parameter evaluation of 20, 30, and 40 ppm C in phenol (Ortiz-Gomez et at, 2008).

This is an auto-oxidation-reduction reaction, the chlorine with oxidation number +i in chlorine dioxide being reduced and oxidized simultaneously to oxidation numbers -f 3 and -f 5. Pure sodium chlorite, NaClOg, can bfe made by passing chlorine dioxide into a solution of sodium peroxide ... 

The investigations of Landesman et al. (1966a, b) clarify the effects of the various conditions controlling the optimum oxidation rates of ferrous iron, sulfur and reduced sulfur compounds by T. ferrooxidans. Experiments on soluble iron, sulfur and iron-containing sulfide minerals (chalcopyrite, CuFeS2, bornite, CUsFeS4, and pyrite) established that iron and sulfur can be oxidized simultaneously. With a mixed iron-sulfur substrate a rate of oxidation, equal to that of the sum of the maximum rates of oxidation of the two substrates individually was observed with both S-adapted and Fe-adapted cells. Subsequently, Duncan et al. (1967) established the differential susceptibility of the bacterial oxidation of ferrous iron and sulfur to N-ethyl maleimide and sodium azide, and determined the effect of these inhibitors on pyrite and chalcopyrite oxidation. Decreased rates... 

A similar mechanism, involving only 1 surface O per exchanged O2 molecule, was proposed by Courbon et a/. It was shown by studying 02/ 02 exchange and CO oxidation simultaneously, that CO has a much greater reactivity with 0 than does O2. 

In Denmark the new SNOX process has been developed by Agerholm et al. [153]. Flue gases with a temperature of about 653 K are cleaned from NO by means of selective catalytic reduction. The gas is reheated up to 673 K and introduced to an SO2 converter which is located downstream from the SCR reactor. SO2 is oxidized into SO3 which is converted to sulfuric acid. The ammonia slip from the SCR reactor is oxidized simultaneously. Advantages of the SNOX process are ... 

Most of the early work on the catalytic oxidation of acetylene resulted in the fonnation of complete combustion products. Thus, in the presence of palladianized asbestos at temperatures above 339° C. carbon dioxide and water were formed if sufficient oxygen was present and carbon monoxide and water if the oxygen was not sufficient for the complete combustion. The hydrogen and carbon were oxidized simultaneously.10" When pure acetylene was passed over palladianized copper oxide, however, water began to form at temperatures as low as 225° to 230° C. but no carbon dioxide. Even at temperatures as high as 400° C. carbon was deposited and the amount of water formed was always in excess of the carbon dioxide.101... 

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