Organic transition metal oxides

Figure 14 A hybrid organic-transition metal oxide network.

In summary, self-organized transition metal oxide nanostructures were successfully synthesised by means of hydrothermal methods. In particular, the microwave-assisted method provides a fast and reliable technique to produce reasonable amounts of material. The nanosized morphology of the materials can influence the reaction behaviour so that higher capacities can be reached (TiOj) than in the bulk or metastable phases can be stabilised (LiCoOj). 

The mechanisms by which transition metal oxidizing agents convert alcohols to aldehydes and ketones are complicated with respect to their inorganic chemistry The organic chemistry is clearer and one possible mechanism is outlined m Figure 15 4 The... 

Alcohol autoxidation is carried out in the range of 70—160°C and 1000—2000 kPa (10—20 atm). These conditions maintain the product and reactants as Hquids and are near optimum for practical hydrogen peroxide production rates. Several additives including acids, nitriles, stabHizers, and sequestered transition-metal oxides reportedly improve process economics. The product mixture, containing hydrogen peroxide, water, acetone, and residual isopropyl alcohol, is separated in a wiped film evaporator. The organics and water are taken overhead and further refined to recover by-product acetone and the... 

Destruction of chlorinated organic solvents in a molten carbonate with transition metal oxides... 

The oxidative cleavage of C=C bond is a common type of reaction encountered in organic synthesis and has played a historical role in the structural elucidation of organic compounds. There are two main conventional methods to oxidatively cleave a C=C bond (1) via ozonol-ysis and (2) via oxidation with high-valent transition-metal oxidizing reagents. A more recent method developed is via the osmium oxide catalyzed periodate oxidative cleavage of alkenes. All these methods can occur under aqueous conditions. 

Reductive dissolution of transition metal oxides by organic reductants can be described as occurring in the following sequence of steps (i) diffusion of reductant molecules to the oxide surface,... 

Transition metal oxide/hydroxides differ in their ability to oxidize organic compounds. Table I lists reduction potentials E° (for [H+]=[Me2+]=1.0M) and E (for [H+]=10 7M and [Me2+]=10 6m) for several first-row transition metals. 

Few studies have systematically examined how chemical characteristics of organic reductants influence rates of reductive dissolution. Oxidation of aliphatic alcohols and amines by iron, cobalt, and nickel oxide-coated electrodes was examined by Fleischman et al. (38). Experiments revealed that reductant molecules adsorb to the oxide surface, and that electron transfer within the surface complex is the rate-limiting step. It was also found that (i) amines are oxidized more quickly than corresponding alcohols, (ii) primary alcohols and amines are oxidized more quickly than secondary and tertiary analogs, and (iii) increased chain length and branching inhibit the reaction (38). The three different transition metal oxide surfaces exhibited different behavior as well. Rates of amine oxidation by the oxides considered decreased in the order Ni > Co >... 

Green Synthesis Of Different Transition Metal Oxide Nanoparticles Potential Catalysts For Removal Of Organic Colorants From Water... 

Redox systems with inorganic and organic components lodonium ions Electron-transfer agents, e.g., alkali metals, alkah-aromatic complexes, alkali metal ketyls Activated transition metal oxides... 

The + 8 oxide is a molecular compound, unlike many transition metal oxides that have giant lattice arrangements, and is quite soluble in water. It has considerable oxidizing properties and is used as an oxidizing agent in many organic reactions. The +4 oxide is insoluble in water. 

A review of recent research, as well as new results, are presented on transition metal oxide clusters, surfaces, and crystals. Quantum-chemical calculations of clusters of first row transition metal oxides have been made to evaluate the accuracy of ab initio and density functional calculations. Adsorbates on metal oxide surfaces have been studied with both ab initio and semi-empirical methods, and results are presented for the bonding and electronic interactions of large organic adsorbates, e.g. aromatic molecules, on Ti02 and ZnO. Defects and intercalation, notably of H, Li, and Na in TiC>2 have been investigated theoretically. Comparisons with experiments are made throughout to validate the calculations. Finally, the role of quantum-chemical calculations in the study of metal oxide based photoelectrochemical devices, such as dye-sensitized solar cells and electrochromic displays, is discussed. 

Reductive dissolution of transition metal oxide/hydroxide minerals can be enhanced by both organic and inorganic reductants (Stone, 1986). There are numerous examples of natural and xenobiotic organic compounds that are efficient reducers of oxides and hydroxides. Organic reductants associated with carboxyl, carbonyl, phenolic, and alcoholic functional groups of soil humic materials are one example. However, large... 

In order to elucidate the importance of the role of in situ formed carbon in the formation of well-organized, highly crystalline mesoporous transition metal oxides, as-synthesized Ti02 was directly calcined under air to 700°C while keeping all other conditions the same as for the CASH method. As expected, the BET surface area of the resulting material was only 0.2 m2 g-1 and no porous structure could be detected by TEM imaging. This implies that the mesostructure completely collapsed. The crystallite size of this sample, heat treated to 700°C in air is 31.5 nm (calculated... 

For oxygen reduction N4-organic metal complexes and conducting polymers, transition metals oxides, perovskites, etc. 

Transition-metal oxides are useful oxidizing reagents for organic molecules and often participate in oxygen-atom transfer reactions [21]. A prototypical example is CH3Re03 (MTO), which serves as a versatile reagent for stoi-... 

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