Oxidation solid-state oxidations

This IS noi a veiy stable state for this group of metals in solution. [MF I and [OsCm" being amongst the few established examples. [i is, however. well-charactcnzcd and stable in numerous solid-state oxide systems (p 1082). 

Oxidation of dihydroquinacridone to quinacridone may be achieved, for instance, with the sodium salt of m-nitrobenzene sulfonic acid in aqueous ethanol in the presence of sodium hydroxide solution [7]. A distinction is made between heterogeneous and homogeneous oxidation. The reaction is referred to as a solid state oxidation if the solvent contains approximately 2% sodium hydroxide solution. A content of approximately 30% sodium hydroxide solution relative to the solvent mixture, on the other hand, converts the reaction into a so-called solution oxidation . The type of ring closure defines the crystal modification of the resulting dihydroquinacridone, while the oxidation technique defines the crystal phase of the quinacridone pigment. 

Solid state oxidation, both of the a- and the 3-phase [8] of dihydroquinacridone, affords crude a-quinacridone. Subsequent milling with salt in the presence of dimethylformamide produces the 7-modification, while the 3-form evolves in the presence of xylene. Solution oxidation of dihydroquinacridone, possibly performed as air oxidation in the presence of 2-chloroanthraquinone [9], forms crude 3-quinacridone. Milling with xylene likewise affords 3-quinacridone pigment (see tables of chemical structures on p. 613). 

T. Akrmoto, S. (1984) Mossbauer study on the high pressure phase ofiron(III) oxide. Solid State Commun. 50 97—100 Szczypa, J. Matysiak, J. Kosmilski, M. (1994) Standard enthalpies of proton adsorption on hematite in various solvent systems. Abstracts of 8 Int. Conf. Colloid Surf. Chem. Adelaide... 

Varma and Naicker published a solid-state oxidative protocol for the transformation of nitriles to amides and of A-heterocycles to A-oxides employing the urea hydrogen peroxide complex (Scheme 156) . The A-oxides depicted in Scheme 156 were synthesized... 

To illustrate the capabilities of the aerosol process for the synthesis of solid state oxidation catalysts not normally obtained from classical synthesis, the preparation of a series of P-V-0 catalysts was examined. The original objective was to determine whether the synthesis of the reported (4) active phase, P-(VO)2P207, of the catalyst responsible for the selective oxidation of butane to maleic anhydride could be synthesized by the aerosol technique. 

Erom the preceding discussion, the distinction between misfit defects shear domains formed by pure shear and CS planes formed by the elimination of anion vacancies in a specific crystallographic plane by shear and the collapse of the oxide lattice on that plane can be understood. This distinction between defects is central to catalytic reaction mechanisms in oxides. However, it is often not made in the literature on oxide catalysis and solid state oxide chemistry. This can result in an incorrect interpretation of observed data and of the role played by lattice oxygen atoms in catalytic reactions. The former are regions containing... 

The solid-state oxidation of a freeze-dried cyclic hexapeptide was examined by Dubost et al. (36). The degradation product was identified as a benzaldehyde derivative resulting from oxidative deamidation of an... 

Oxidations for varying times showed systematic variations in the U +/U + ratios that fell into three values stable for significant periods of time (Fig. 5). These ratios of U +/U + = 0.5, 1.0 and 2.0 are believed to correspond to the presence of U3O7 (U02 U02 U03), U205 (U02 U03), and U30g (U02-U03-U03), respectively. The surface film composition is controlled by various rates of surface dissolution, oxygen diffusion into the UO2 and precipitation. Film dissolution is believed to occur upon oxidation to UO3. Because no appreciable layer of UO3 was found on the surface, it is concluded that dissolution of UO3 occurs at a rate faster than solid-state oxidation. 

Helmut Ullmann, Nikolai Trofimenko, Composition, structure and transport properties of perovskite-type oxides , Solid State Ionics 119,1-8 (1999). 

Greaves, C. (1983) A powder neutron diffraction investigation of vacancy and covalencein y-ferric oxide. Solid State Comm., 30, 257-63. 

Tab. 26. Copper(ll)-catalyzed, solid-state oxidative dimerizations of substituted 2-naphthol derivatives.

In some experimental situations it is not desirable to use a glass electrode to measure pH. In these cases solid-state oxide-based pH sensors can be used. Obviously the pH range in which they can be... 

Carlino, S., Hudson, M. J., Husain, S. W. and Knowles, J. A. (1996). The reaction of molten phenylphosphonic acid with a layered double hydroxide and its calcined oxide. Solid State Ionics 84, 117. 

All explosive materials contain oxygen, which is needed for the explosive reaction to take place. The oxygen can be introduced by chemical reactions (nitration) or by mechanical incorporation of materials containing bound oxygen. The most important solid-state oxidizers are nitrates, especially -> Ammonium Nitrate and -> Sodium Nitrate for explosives -> Potassium Nitrate for -> Black Powder and ion exchanged -> Permitted Explosives, potassium chlorate for -> Chlorate Explosives and for pyrotechnical compositions Ammonium Perchlorate (APC) for -> Composite Propellants. 

Crystals of 2 -Deoxyguanosine 5 -Monophosphate Tetrahydrate Disodium Salt (5 -dGMP) have a neutral guanine base. In the solid-state, oxidation of 5 -dGMP at 10 K leads to deprotonation at the exocyclic nitrogen which is characterized by p(C8) = 0.175 and p(N2) = 0.33 [37], The same radical was detected in crystals of 3, 5 -cyclic guanosine 5 -monohydrate. In this second study, the N3 spin density was determined to be 0.31 [38], These two studies then provide a detailed description of the amino deprotonated guanine cation G(N2-H) ... 

Thermal oxidation studies of unnotched and uncracked specimens of Al203/SiC composites also reveal the formation of carbon-rich and silicon-rich reaction layers via solid-state oxidation of the SiC whisker according to the reaction 56... 

Gas-solid reactive sintering can also be used in the oxidation of most metals or, more important, mixtures of metals. After oxidation, solid state sintering takes place. With mixtures of metals, a mixed oxide is produced which can be sintered by either solid state or liquid phase sintering. One example of alloy oxidation to produce a ceramic is in the synthesis of the superconductor YBa2Cu3Q. ... 

---