Through Oxidation in Air

Oxidation of tellurolates generally produces diorgano ditellurium compounds (p. 264,270). However, the oxidation of ethynetellurolates led to the isolation of diethynyl tellurium products. When sodium ethynetellurolates were hydrolyzed with water in the presence of air, the diethynyl tellurium products were obtained in low yields. Oxidation by iodine in DMSO improved the yield to 70% . The expected ditellurium compounds were postulated as unstable intermediates. 

Bis[phenylethynyl] Tellurium A solution of 6.3 g (25 mmol) of iodine in 20 ml of DMSO is added dropwise to a solution of 50 mmol of sodium phenylethynetellurolate in 50 ml of DMSO. Tellurium is filtered off, water is added to the filtrate, and the mixture is extracted with chloroform. The solvent is evaporated and the residue is recrystallized from petroleum ether yield 5.7 g (70%) m.p. 81°. 

Oxidation of the hydrolyzed tellurolates with air gave bis phenylethynyl] tellurium in 15% yield and bis[4-methylphenylethynyl] tellurium (m.p. 120°) in 14% yields 

From Diisobutylaluminum Benzenetellurolate and a,/l-unsaturated Carbonyl Compounds 

Diisobutylaluminum benzenetellurolate, prepared from diphenyl ditellurium and diisobutylaluminum hydride, adds in a 1,4-fashion to a,/l-unsaturated aldehydes, ketones, and carboxylic acid esters to give as intermediates /i-phenyltelluro-substituted aluminum enolates that can be hydrolyzed to the carbonyl compounds or reacted with aldehydes to produce aldol adducts.  

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Recently Nitto Denko developed a battery separator made by a wet process that had high puncture strength and high heat rupture resistance. They used a polyolefin resin with a high-molecular-weight rubber as its main component materials and cross-linked through oxidation in air. The melt rupture temperature, as measured by thermomechanical analysis, was over 200°C in this material. They also tried cross-linking UHMWPE with electron-beam and ultraviolet irradiation, but this had the... 

The pigment is prone to discoloration through oxidation in air (Woudhuysen-Keller and Woudhuysen, 1998). Ginm et al. (1999) have shown that the brown layers which form over time are oleresinous layers (copper oleates and copper proteinates), caused by the relative ease of extraction of copper(II) ions fiem verdigris by fatty acids, proteins and waxes present in the binding media or overlying varnishes. 

An improved approach from the point of view of thermal efficiency is the electrothermal process in which the mixture of zinc oxide and carbon, in the form of briquettes, are heated in a vertical shaft furnace using the electrical resistance of the briquettes to allow for internal electrical heating. The zinc vapour and CO(g) which are evolved are passed through a separate condenser, the carbon monoxide being subsequently oxidized in air. 

Figure 2 shows the typical steps in junction preparation. The aluminum strip is evaporated onto a glass slide through a mask. After the surface is oxidized in air or O2 glow discharge, it is... 

The monoanion (SSn = —30.3) and dianion (5Sn = 186.7) of the phenylstannoles have been prepared through the bis(stannole) as their lithium derivatives as shown in Scheme 7.237 238 The l-t-butyl-2,3,4,5-tetraphenylstannole anion is oxidized in air to the corresponding bis(stannole).239... 

All isotopes of plutonium are radioactive. The two isotopes that have found the most uses are Pu-238 and Pu-239. Pu-238 is produced by bombarding U-238 with deuterons in a cyclotron, creating neptunium-238 and two free neutrons. Np-238 has a half-life of about two days, and through beta decay it transmutates into plutonium-238. There are six allotropic metallic crystal forms of plutonium. They all have differing chemical and physical properties. The alpha (a) aUotrope is the only one that exists at normal room temperatures and pressures. The alpha allotrope of metallic plutonium is a silvery color that becomes yellowish as it oxidizes in air. AH the other allotropic forms exist at high temperatures. 

It combines with sulfur dioxide to form calcium sulfite hemihydrate, CaSOs MiH20 which can oxidize in air in the presence of moisture to give calcium sulfate dihydrate, CaS04 2H2O. However, when SO2 is passed through a solution of calcium hydroxide, calcium bisulfite, Ca(HS03)2 is obtained. The solution is yellowish when it contains bisulfite in aqueous SO2. 

One way to remove arsenic from drinking water in Bangladesh is by coprecipitation with Fe(OH)3.6 Fe(ll) or Fe(s) is added to the water and allowed to oxidize in air for several hours to precipitate Fe(OH)3. After filtration through sand to remove solids, the wdter is drinkable. 

Ethylene oxide in air may be measured directly in situ by a rapid colorimetric technique (Pritts et al., 1982). Air is drawn through a multipart detector tube consisting of three reactor tubes containing periodic acid, xylene, and cone. E12S04, respectively. Ethylene oxide is oxidized by periodic acid to formaldehyde... 

The alkylhydroperoxides are also interesting because of their formation in natural products. Unsaturated fatty acids and their esters (plant oils) are oxidized in air to peroxides (auto-oxidation). This leads to a stepwise breaking of the double bonds leading to the formation of aldehydes, ketones and fatty acids, all of which make their presence known through their strong odor intensities (e.g. rancid oil). 

Sodium is a soft, malleable solid readily cut with a knife or extruded as wire. It is commonly coated with a layer of white sodium monoxide, carbonate, or hydroxide, depending on the degree and kind of atmospheric exposure. In a strictly anhydrous inert atmosphere, the freshly cut surface has a faintly pink, bright metallic luster. Liquid sodium in such an atmosphere looks much Eke mercury. Both liquid and solid oxidize in air, but traces of moisture appear to be required for the reaction to proceed. Oxidation of the liquid is accelerated by an increase in temperature, or by increased velocity of sodium through an air or oxygen environment. 

The previously isolated1654 / // -/rtitanium dichloride has been prepared by a new route, involving the reductive dimerization of 6-phenylfulvene with activated calcium powder followed by treatment with TiCl3/AlCl3 (1 3) and oxidation in air. This complex has been used to synthesize a variety of other // -derivatives through ligand replacement (Scheme 642). The reaction of 6,6-diphenylfulvene... 

Hydrometallurgy makes use of redox and complexation reactions for the recovery of valuable metals from ores. This is exemplified by the dissolution of gold metal in ores through oxidation by air and complexation by cyanide. 

Fig.5. Electron image (A) and Fe (B), Cr (C), A1 (D) and l i (F.) X-ray images of a transverse cross-section through FeCrAlY coated Ti3Al after lOOOh oxidation in air at 800°C...

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