Reactions with binary oxides

Many oxides react with CCI., when heated, to generate phosgene. Indeed, the 

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Phase diagrams are extremely useful in determining the reactions that occur when alkali oxides react with many common ceramics. Most scientists and engineers are easily able to evaluate binary phase diagrams that correspond to an alkali reaction with single oxide ceramics however, when multi-oxide ceramics such as mullite are involved, multi-component phase diagrams are not fully used and extremely time-consuming experimentation is unnecessarily conducted. 

Many of the perovskite compounds can be prepared by high-temperature solid-state reaction of binary oxides or peroxides. However, some of these tend to be refractory and hence unreactive. Others have a tendency to hydrate or oxidize and are inconvenient to use. Therefore, it is preferable to use carbonates, oxalates, or other easily decomposable compounds, assuming they can be obtained with suitable purity. These materials are usually in the form of fine powders and decompose in the initial stages of the reaction so that faster reaction rates are obtained. In some cases fine powders may be obtained by... 

Other important uses of stannic oxide are as a putty powder for polishing marble, granite, glass, and plastic lenses and as a catalyst. The most widely used heterogeneous tin catalysts are those based on binary oxide systems with stannic oxide for use in organic oxidation reactions. The tin—antimony oxide system is particularly selective in the oxidation and ammoxidation of propylene to acrolein, acryHc acid, and acrylonitrile. Research has been conducted for many years on the catalytic properties of stannic oxide and its effectiveness in catalyzing the oxidation of carbon monoxide at below 150°C has been described (25). 

Ir catalysts supported on binary oxides of Ti/Si and Nb/Si were prepared and essayed for the hydrogenation of a,P-unsaturated aldehydes reactions. The results of characterization revealed that monolayers of Ti/Si and Nb/Si allow a high metal distribution with a small size crystallite of Ir. The activity test indicates that the catalytic activity of these solids is dependent on the dispersion obtained and acidity of the solids. For molecules with a ring plane such as furfural and ciimamaldehyde, the adsorption mode can iirfluence the obtained products. SMSI effect (evidenced for H2 chemisorption) favors the formation of unsaturated alcohol. 

A novel polysiloxane, containing the isocyanide group pendent to the backbone, has been synthesized. It is observed to react with the metal vapors of chromium, iron and nickel to afford binary metal complexes of the type M(CN-[P])n, where n = 6, 5, 4 respectively, in which the polymer-attached isocyanide group provides the stabilization for the metal center. The product obtained from the reaction with Fe was found to be photosensitive yielding the Fe2(CN-[P])q species and extensive cross-linking of the polymer. The Cr and Ni products were able to be oxidized on exposure of thin films to the air, or electrochemically in the presence of an electron relay. The availability of different oxidation states for the metals in these new materials gives hope that novel redox-active polymers may be accessible. 

The theory of chain co-oxidation of binary mixtures of organic compounds was described in Chapter 5. The experimental study of co-oxidation of alcohols (HRiOH) and hydrocarbon R H opens the way to measure the rate constants of one chosen peroxyl radical R OO with several alcohols HRiOH and on the reverse, the chosen alcohol HR1 OH with several peroxyl radicals RiOO. The parameters of co-oxidation of alcohols and hydrocarbons are collected in Table 7.6. The absolute values of peroxyl radical reactions with alcohols were calculated from these data using the values of kp from Table 2.8 (see Table 7.7). 

Bimolecular surface reactions reactants adsorption, 29 111-112 with single reactant, 29 108-109 1,1 -Binaphthyl, dehydrocyclization, 28 318 Binary oxides, 32 119 Binding energy, 32 160-162 chemisorbed sulfur, 37 281 hydrogen, sulfur effect, 37 295-296 shift, Pd, 37 62-64 ZnO/SiOj, 37 21-22 Binor-S, see Norbomadiene Biological systems, hydrogen in, activation of, 11 301... 

Metal oxides, 31 78-79, 89, 102, 123, 157-158, 191, 32 199-121 see also Amorphous metal oxides Sulfate-supported metal oxides specific oxides adsorbed oxygen on, 27 196-198 binary, surface acidity, 27 136-138 catalytic etching, 41 390-396 coordination number, 27 136 electrocatalysts, 40 127-128 Fe3(CO)i2 reaction with, 38 311-314 Lewis acid-treated, 37 169-170 multiply-valent metals, electrocatalytic oxidations, 40 154-157 superacids by, 37 201-204 surface acidity, methods for determining, 27 121... 

The relatively facile formation of anhydrovinblastine (42) by the modified Polonovski reaction, and the poor yields experienced on coupling of other catharanthine derivatives, made anhydrovinblastine an attractive precursor for the preparation of additional binary alkaloids, including vinblastine itself (50,57). Hydrogenation to 20 -deoxyleurosidine (61a), formation of its Af -oxide (78), and reaction with trifluoroacetic anhydride led to the enamine 59 (Scheme 23). Oxidation of this enamine with thal-... 

A second-order structural transformation in La uC at 233 5°C was reported (118) in a thermal expansion study. The LajCu04 product was prepared at high temperature (1100°C) by the solid-state reaction of the corresponding binary oxides. The material was found to decompose above 1200°C with the loss of oxygen. Samples of La uC, prepared at 1200°C, then maintained at 750°C in vacuum, yielded products having the general composition La2Cu04.x, or... 

While a binary oxide can be used as a starting material, some of these are reactive compounds that are difficult to handle. For example, BaO reacts rapidly with C02 in the air to produce barium carbonate. Other oxides, including BaO, are hygroscopic. Thus, compounds which are unreactive towards C02 and HzO at room temperature, but decompose to oxides plus volatile gases at elevated temperatures, are often used as oxide precursors. In the case of barium, BaCOs is a stable compound under ambient conditions but decomposes upon heating to 950°C according to the reaction... 

Formation of Ternary Oxides12 Many compounds of mineralogical importance are ternary compounds of oxygen with a formula ABaO +, where A = Ca, Mg, Mn, Fe, Co, and Ni, and B = Si, W, C, and S. These compounds may be considered to be formed from the reaction of the binary oxides. That is... 

The second major section will focus on those special centers of minerals thought to be of importance to their catalytic activity, with an emphasis on the known and possible effects of electronic excitation on the population and mode of action of these centers. Metastable states constitute a hidden variable in defective solids, a non-negligible one for non-stoichiometric ones. With regard to concepts of mineral catalysis, the only systems for which extensive spectroscopic information on mineral catalytic centers has been definitively coupled to the mechanism of a well understood surface chemical reaction is exchange on binary oxides. Existing data for the... 

Use published data concerned with Hj/D2 exchange on binary oxides to update current insights regarding reaction-promoting active sites on mineral surfaces and their modes of production ... 

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