Triple oxidation

Dispenser cathodes were designed to have a current-loading density many times that of the conventional triple-oxide cathodes. This enabled the CRT to run at much higher beam currents with brightness and resolution much better than prior CRT s because the electron beam could be focused to a smaller spot. 

Through the sol—gel process, single oxides such as silica can he synthesized with an organically modified surface, as well as double or triple oxides [9] such as Si— Al, Si—Ti, Si—Zr, A1—Zr, A1—Ti, and A1—Ti—Zr. For such syntheses, 1,10-diaminedecane and 1,12-diaminedodecane, as well as a surfactant such as dodecyl-trimethylammonium bromide, can be used, with the final modified oxides exhibiting lamellar or hexagonal nanostructure. Such compounds with modified surface are also able to coordinate transition metal cations. 

Titanium dioxide is a well-known photocatalyst for air purification, exhibiting other possible applications [11]. In this connection, the sol-gel process has been successfully used for the preparation of a series of titania containing single, double, or triple oxides with regular nanostructure [12-17],... 

Electrodes consisting of triple oxides of Ti-V-W-O/Ti and Ti-V-W-O/C were also suggested. The oxide layer of the Ti-V-W-O/Ti electrodes consisted of WO3 and Ti Vy02 oxides of the rutile type. The maximum capacitance of 125 F/g was also found for electrodes of this type. 

Above 570 °C, we observe the formation of a triple oxide layer that, from the metal-oxide interface outwards, is composed of wustite, magnetite and then hematite (Figure 9.17). The oxygen ion content of the triple layer thus increases as one moves from the interior to the outside. Different oxidation reactions take place at the interfaces. At the metal-wustite interface, iron is oxidized into Fe, whereas at the wustite-magnetite and magnetite-hematite interfaces, the Fe is transformed into Fe +. 

We know that double oxidative addition of an alkene to a metal to produce a metal-bis-carbene or triple oxidative addition of an alkyne to produce a metal-bis-carbyne complex is not possible. Olefin insertion into a metal-hydride giving a metal-alkyl, however, can be followed by a-elimination to yield a hydrido-metal-carbene or even further double a-elimination can give a hydrido-metal-carbyne. Such a case is known the reaction of styrene or phenylacetylene with [Os(H)Cl2L2] (L = Pi-Pr3) yields the carbyne complex [OsHCl2(CCH2Ph)L2] via the metal-carbene intermediate. PhEt is also formed as a result of hydride consumption (K.G. Caulton, J. Organomet. Chem. 2001,617-618,56). 

The position of the triple bond is established by oxidation of the latter by means of alkaline potassium permanganate solution to sebacic acid, H02C(CH2)gC0jH, m.p. 133°. 

Alkynes undergo stoichiometric oxidative reactions with Pd(II). A useful reaction is oxidative carboiiyiation. Two types of the oxidative carbonyla-tion of alkynes are known. The first is a synthesis of the alkynic carbox-ylates 524 by oxidative carbonylation of terminal alkynes using PdCN and CuCh in the presence of a base[469], Dropwise addition of alkynes is recommended as a preparative-scale procedure of this reation in order to minimize the oxidative dimerization of alkynes as a competitive reaction[470]. Also efficient carbonylation of terminal alkynes using PdCU, CuCI and LiCi under CO-O2 (1 I) was reported[471]. The reaction has been applied to the synthesis of the carbapenem intermediate 525[472], The steroidal acetylenic ester 526 formed by this reaction undergoes the hydroarylalion of the triple bond (see Chapter 4, Section 1) with aryl iodide and formic acid to give the lactone 527(473],... 

Triple-distiUed mercury is of highest purity, commanding premium prices. It is produced from primary and secondary mercury by numerous methods, including mechanical filtering, chemical and air oxidation of impurities, drying (qv), electrolysis, and most commonly multiple distillation. 

In general, peroxomonosulfates have fewer uses in organic chemistry than peroxodisulfates. However, the triple salt is used for oxidizing ketones (qv) to dioxiranes (7) (71,72), which in turn are useful oxidants in organic chemistry. Acetone in water is oxidized by triple salt to dimethyldioxirane, which in turn oxidizes alkenes to epoxides, polycycHc aromatic hydrocarbons to oxides and diones, amines to nitro compounds, sulfides to sulfoxides, phosphines to phosphine oxides, and alkanes to alcohols or carbonyl compounds. 

The triple salt is classified by the UN not as an oxidizer but as a corrosive, and thus must be transported under the UN No. 1759 for corrosive soHds NOS. It should be kept away from combustible material. 

Properties. Thallium is grayish white, heavy, and soft. When freshly cut, it has a metallic luster that quickly dulls to a bluish gray tinge like that of lead. A heavy oxide cmst forms on the metal surface when in contact with air for several days. The metal has a close-packed hexagonal lattice below 230°C, at which point it is transformed to a body-centered cubic lattice. At high pressures, thallium transforms to a face-centered cubic form. The triple point between the three phases is at 110°C and 3000 MPa (30 kbar). The physical properties of thallium are summarized in Table 1. 

Oxidation of Chlorides. Hypochlorite can also be formed by the in situ oxidation of chloride ions by potassium peroxymonosulfate [25482-78-4] (36). Ketones like acetone cataly2e the reaction (37). The triple salt of potassium peroxymonosulfate is a stable powder that has been combiaed with chloride salts and sold as toilet bowl cleaners. Bromides can be used ia place of chlorides to form hypobromites, and such combiaations are used to disiafect spas and hot tubs. 

Fig. 2. Cables of parallel SWNTs thal have self-assembled during oxidative cleanup of arc-produced soot composed of randomly oriented SWNTs imbedded in amorphous carbon. Note the large cable consisting of several tens of SWNTs, triple and single strand tubes bent without kinks, and another bent cable consisting of 6 to 8 SWNTs.

The molecular orbital description of the bonding in NO is similar to that in N2 or CO (p. 927) but with an extra electron in one of the tt antibonding orbitals. This effectively reduces the bond order from 3 to 2.5 and accounts for the fact that the interatomic N 0 distance (115 pm) is intermediate between that in the triple-bonded NO+ (106 pm) and values typical of double-bonded NO species ( 120 pm). It also interprets the very low ionization energy of the molecule (9.25 eV, compared with 15.6 eV for N2, 14.0 eV for CO, and 12.1 eV for O2). Similarly, the notable reluctance of NO to dimerize can be related both to the geometrical distribution of the unpaired electron over the entire molecule and to the fact that dimerization to 0=N—N=0 leaves the total bond order unchanged (2 x 2.5 = 5). When NO condenses to a liquid, partial dimerization occurs, the cis-form being more stable than the trans-. The pure liquid is colourless, not blue as sometimes stated blue samples owe their colour to traces of the intensely coloured N2O3.6O ) Crystalline nitric oxide is also colourless (not blue) when pure, ° and X-ray diffraction data are best interpreted in terms of weak association into... 

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