Oxidants typical

Several 1,4-dicarbonyl compounds are prepared based on this oxidation. Typically, the 1,4-diketone 10 or the 1,4-keto aldehyde 12 can be prepared by the allylation of a ketone[24] or aldehyde[61,62], followed by oxidation. The reaction is a good annulation method for cyclopentenones (11 and 13). Syntheses of pentalenene[78], laurenene[67], descarboxyquadrone[79], muscone (14 R = Me)[80]) and the coriolin intermediate 15[71] have been carried out by using allyl group as the masked methyl ketone (facing page). 

Meta.1 Oxides. Halogen-containing elastomers such as polychloropreae and chlorosulfonated polyethylene are cross-linked by their reaction with metal oxides, typically ziac oxide. The metal oxide reacts with halogen groups ia the polymer to produce an active iatermediate which then reacts further to produce carbon—carbon cross-links. Ziac chloride is Hberated as a by-product and it serves as an autocatalyst for this reaction. Magnesium oxide is typically used with ZnCl to control the cure rate and minimize premature cross-linking (scorch). 

Sulfation Roasting. Acid roasting technology (Fig. 2) rehes on differences in the volatiUty of the tetravalent oxides of selenium and tellurium at roasting temperatures of 500—600°C to selectively volatilise selenium from slimes. Acid roasting uses sulfuric acid as the oxidant for the conversion of selenium/selenides and tellurium/teUurides to their respective tetravalent oxides. Typical oxidation reactions are as foUow ... 

Two pigment production routes ate in commercial use. In the sulfate process, the ore is dissolved in sulfuric acid, the solution is hydrolyzed to precipitate a microcrystalline titanium dioxide, which in turn is grown by a process of calcination at temperatures of ca 900—1000°C. In the chloride process, titanium tetrachloride, formed by chlorinating the ore, is purified by distillation and is then oxidized at ca 1400—1600°C to form crystals of the required size. In both cases, the taw products are finished by coating with a layer of hydrous oxides, typically a mixture of siUca, alumina, etc. 

The yellow form (11) on acidification is converted to the more stable thiol form (12). On oxidation, typically with alkaline ferhcyanide, yellow form (11) is irreversibly converted to thiochrome [299-35-4] (14), a yellow crystalline compound found naturally in yeast but with no thiamine activity. In solution, thiochrome exhibits an intense blue fluorescence, a property used for the quantitative determination of thiamine. 

The calcareous materials contain calcium carbonate or calcium oxide. Typical raw calcareous materials are as follows ... 

Anti-oxidants are the most extensively used additives and will be found in oils and greases which are expected to operate for considerable periods or under conditions that would promote oxidation. Typical examples are crankcase oils and bearing greases. 

When present as a minor constituent, iron oxides typically impart a tan to brown color to the overall deposit. When iron oxides are present as a major constituent, the color is red-brown to black. Where iron oxides are found, copper oxides usually are also present (typically at 10-15% of the amount of iron oxide concentration). 

C) for cast iron and up to 140 °F for marstenitic SS (60 °C). It is widely used where silicates are present with the iron oxides. Typically, 5 to 7.5% HC1 is employed. The ammonium bifluoride normally is present at 0.5%, but it may be increased to a maximum of 1.5% for a boiler that has not been cleaned for many years. The presence of hydrofluoric acid (HF), which is formed by the reaction of ammonium bifluoride with HC1 (see equation), tends to increase the rate of iron oxide dissolution and reduce the corrosion rate of exposed steel, when compared to using HC1 alone. This is due to the stability of the hexafluoroferric ion (FeFg3 ), which prevents the ferric ion from corroding exposed steel. 

Increase in surface-to-volume ratio by anodic oxidation Typical length of reactor (with diffusers) 17 mm... 

Particulate iron oxides, Typical water flows lOOOgal/t heavy metals, fluorides... 

Chemical oxidation typically involves reduction/oxidation (redox) reactions that chemically convert hazardous contaminants to nonhazardous or less toxic compounds that are more stable, less mobile, or inert. Redox reactions involve the transfer of electrons from one compound to another. Specifically, one reactant is oxidized (loses electrons) and one is reduced (gains electrons). The oxidizing agents... 

Comparison of chemiluminescence isothermal runs with oxygen uptake and DSC measurements has been at the centre of interest since practical industrial applications of the chemiluminescence method were attempted. It is a fact that the best comparison may be achieved when studying polymers that give a distinct induction time of oxidation typical for autoaccelerating curves of a stepwise developing oxidation. This is the particular case of polyolefins, polydienes and polyamides. The theoretical justification for the search of a mutual relationship between the oxidation runs found by the various methods follows directly from the kinetic analysis of the Bolland-Gee scheme of polymer oxidation. 

The chemical composition of particles can be just as varied as their shape. Commercial particles can consist of polymers or copolymers, inorganic constructs, metals and semiconductors, superparamagnetic composites, biodegradable constructs, and synthetic dendrimers and dendrons. Often, both the composition of a particle and its shape govern its suitability for a particular purpose. For instance, composite particles containing superparamagnetic iron oxide typically are used for small-scale affinity separations, especially for cell separations followed by flow cytometry analysis or fluorescence-activated cell sorting (FACS). Core-shell semiconductor particles, by... 

Aerobic treatment of aquifer oxygen is usually supphed by one of three methods direct air sparging of air or oxygen into wells screened below the contaminated zone, saturation of water with air or oxygen prior to reinjection, or addition of an oxidant (typically a peroxide compound) directly into an injection well or injection water. Regardless of the mechanism of introduction, the important factor is that the oxidant is distributed throughout the contaminated zone at a concentration and rate such that it can be utilized by the microorganisms. 

Unlike the aryl methyl selenides, the alkyl aryl selenides with alkyl groups of two carbons or more are able to undergo scission of the radical cation at the Cgp-Se bond, yielding the ArSe radical (Fig. 35). This can impact product distribution, particularly under conditions in which water is not present to react with the radical cation. Trends in ease of oxidation typically seen in series of chalcogen compounds can still be observed, and are consistent with trends in the diaryl chalcogenides and aryl methyl chalcogenides. 

PB also can be oxidized to give first a green material, Berlin Green (BG), in the partially oxidized state, and then finally a yellow material, Prussian Yellow (PY), in the fully oxidized state. This oxidation typically occurs between 0.8 and 1.0 V vs. SCE. The complete oxidation of Prussian Blue to Prussian Yellow is shown in the following equation. 

In aqueous solutions containing counterions this oxidation typically occurs near 0.8 V vs. SCE. Other counterions besides Kmay be incorporated into PB and its derivatives, changing the energetics of the various redox transitions. The ability to reversibly oxidize or reduce all of a given type of metal center in PB and its derivatives endows PB with behavior similar to that described above for many other electroactive NPs. 

The azide chemical bond, represented by -N3, contains thermal energy, which is released when the bond is broken without oxidation. Typical chemicals containing azide bonds are glycidyl azide polymer, designated as GAP, BAMO, and AMMO. These polymers are copolymerized with hydrocarbon polymers to formulate fuel-... 

Rh, Ru, Pd) and oxides (<4wt% Fe jO4/Cr2O3, La2O3, SnO2, K2O) was recently performed by Lodeng et al. [134]. A comparison with Ni- and Fe-based catalysts was also addressed. It was found that addition of metal promoters, particularly Rh and Pt, enhanced the catalyst activity at low temperatures (which resulted in delayed extinction of the reaction during ramping at —1 Tmin ). However, addition of Ni promoted carbon formation. Addition of surface oxides typically promoted instability, deactivation and combustion (hence the formation of a stable Co metallic phase was hindered). It was found that Ni performed better than Co-based catalysts at all temperatures. However, Fe-based catalysts showed high combustion activity. 

The -oxygenation of cyanatryn occurred readily with liver microsomes and 10,000 g supernatant (the latter was fortified with GSH and the observed product was the glutathione conjugate [5]). The reaction could be detected in 2% liver homogenates but not in homogenates of kidney, lung, intestine, or caecal content. The reaction was readily catalyzed by microsomes from the livers of male and female rats, male and female rabbits and a male human (Table 1)(9). The rat sex difference was much larger for N-de-ethylation than for -oxidation. Typically, microsomes from male rats were more active than those from females. 

Craujis H Ighar " li-foruiliig Oxides Typical or Ini small Period Iarg Period ... 

Table 15.9 Thermal and Physical Properties of Polyphenylene Oxide (Typical...

AN. A small fraction of NiO (Nickel oxide, typically 3%) imbedded into the AN crystals is also used for phase stabilization. 

Isolated examples of oxidation at nitrogen have been reported for these systems. They do not form the N-oxides typical of aromatic nitrogen heterocycles, but behave similarly to amines. Thus the 1,2,5-oxadiazine (80) is rapidly oxidized by lead dioxide to the radical (81) (73JA1677), which is in equilibrium with the four-membered ring radical (82). 

Phenols attached to insoluble supports can be etherified either by treatment with alkyl halides and a base (Williamson ether synthesis) or by treatment with primary or secondary aliphatic alcohols, a phosphine, and an oxidant (typically DEAD Mitsu-nobu reaction). The second methodology is generally preferred, because more alcohols than alkyl halides are commercially available, and because Mitsunobu etherifications proceed quickly at room temperature with high chemoselectivity, as illustrated by Entry 3 in Table 7.11. Thus, neither amines nor C,H-acidic compounds are usually alkylated under Mitsunobu conditions as efficiently as phenols. The reaction proceeds smoothly with both electron-rich and electron-poor phenols. Both primary and secondary aliphatic alcohols can be used to O-alkylate phenols, but variable results have been reported with 2-(Boc-amino)ethanols [146,147]. 

Mixed addenda or transition-metal-ion-substituted heteropolyanions containing Co, Mn, and Ru are catalysts for oxidation reactions with tert-butyl hydroperoxide and other oxidants. Typical examples are listed in Table XXX. 

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