Solid state reactions with

Traditionally one categorizes matter by phases such as gases, liquids and solids. Chemistry is usually concerned with matter m the gas and liquid phases, whereas physics is concerned with the solid phase. However, this distinction is not well defined often chemists are concerned with the solid state and reactions between solid-state phases, and physicists often study atoms and molecular systems in the gas phase. The tenn condensed phases usually encompasses both the liquid state and the solid state, but not the gas state. In this section, the emphasis will be placed on the solid state with a brief discussion of liquids. 

A. K. Galwey, Reactions in the Sohd State, in Bamford and Tipper, eds.. Comprehensive Chemical Kinetics, vol. 22, Elsevier, 1980. Galwey, A. K., Chemistry of Solids, Chapman and Hall, 1967. Sohn, H. Y, and W. E. Wadsworth, eds.. Rate Frocesses of Extractive Metallurgy, Plenum Press, 1979. Szekely, J., J. W. Evans, and H. Y. Sohn, Gas-Solid Reactions, Academic Press, 1976. Uhmann, ed., Enzyklopaedie der technischen Chemie, Uncatalyzed Reactions with Solids, vol.. 3, 4th ed., Verlag Chemie, 1973, pp. 395-464. 

A CVD reaction can occur in one of two basic systems the closed reactor or the open reactor (also known as close or open tube). The closed-reactor system, also known as chemical transport, was the first typetobeusedforthe purification of metals. It is a hybrid process which combines vapor-phase transfer with solid-state diffusion. As the name implies, the chemicals are loaded in a container which is then tightly closed. A temperature differential is then applied which provides the driving force for the reaction. 

This is a dynamic electrochemical technique, which can be used to study electron transfer reactions with solid electrodes. A voltammo-gram is the electrical current response that is due to applied excitation potential. Chapter 18b describes the origin of the current in steady-state voltammetry, chronoamperometry, cyclic voltammetry, and square wave voltammetry and other pulse voltammetric techniques. 

Arc-melting Well mixed (in some cases partially pre-reacted) compacts of carbon and the metal may be reacted by melting arc-melting may be especially suitable. An advantage of melting in comparison with solid-state reactions may be related to the fact that arc-melted pieces have a smooth surface less susceptible to contamination. This method was found especially effective for refining and for the preparation of solid solutions mainly of the 4th and 5th carbides groups. 

A series of solid-state reactions has been explored by Kaupp et al., in which gaseous amines were reacted with aldehydes to give imines. Analogous reactions with solid anhydrides, imides, lactones or carbonates, and isothiocyanates were used to give, respectively, diamides or amidic carboxylic salts or imides, diamides, carbamic acids, and thioureas [24]. In general the yields were found to be quantitative. Ammonia and other gaseous amines, in particular methyl-amine, have also been shown to aminolyse thermoplastic polycarbonates [25]. 

These reactions are solid-state insertion electrochemical processes with coupled electron and ion transfers. Figure 4 includes the standard potential of hex-acyanoferrate in aqueous solution. It is rather surprising that the data for the solid-state insertion electrochemistry and... 

Carbonylation reactions with microwave irradiation have been investigated in connection with solid-state combinatorial chemistry.Since reactions requiring gaseous reagents cannot use microwave irradiation, metal carbonyl complexes, such as Mo(CO)6, Cr(CO)6, W(CO)6, and Co2(CO)8 have been employed as source of carbon monoxide. " Examples of aminocarbonylation performed with microwave irradiation are presented in Section 11.15.4.3 (vide supra). 

First-order adsorption kinetics model A simple first-order reaction model is based on a reversible reaction with equilibrium state being established between two phases (A— fluid, B—solid) ... 

In the preceding decade, solid-state NMR spectroscopy has provided important and novel information about the nature and properties of surface sites on working solid catalysts and the mechanisms of these surface reactions. This spectroscopic method offers the advantages of operation close to the conditions of industrial catalysis. A number of new techniques have been introduced and applied that allow investigations of surface reactions by solid-state NMR spectroscopy under both batch and flow conditions. Depending on the problems to be solved, both of these experimental approaches are useful for the investigation of calcined solid catalysts and surface compounds formed on these materials under reaction conditions. Problems with the time scale of NMR spectroscopy in comparison with the time scale of the catalytic reactions can be overcome by sophisticated experimental... 

Chapters 6 and 7 dealt with solid state reactions in which the product separates the reactants spatially. For binary (or quasi-binary) systems, reactive growth is the only mode possible for an isothermal heterogeneous solid state reaction if local equilibrium prevails and phase transitions are disregarded. In ternary (and higher) systems, another reactive growth mode can occur. This is the internal reaction mode. The reaction product does not form at the contacting surfaces of the two reactants as discussed in Chapters 6 and 7, but instead forms within the interior of one of the reactants or within a solvent crystal. 

Solid state reactant Thermal decompositions of a solid Oxidation or reduction of a solid Precipitation Solution heating or cooling Evaporative salting-out Chemical reaction with insoluble product Hydrothermal synthesis Forced insolubility Dissolution reprecipitation Evaporative Condensation Gas phase reaction with solid product Thermal decompositions Oxidation or reduction reactions Combination reactions with a solid product Solvent removal Spray drying Freeze drying Spray roasting Sol-gel synthesis Melt solidification... 

Taraban E.A., Krivomchko O.P., Buyanov R.A. et al. Dehydration reactions and solid-state interactions in thermal treatment of mechanical mixtures of crystal hydroxides Al" with hydroxides Zn" Zhum. Neorgan. Khim. 1988 33 1824-28. 

Metal oxides are widely used as catalyst supports. For instance, a-Al203 is employed as a support for catalysts in the partial oxidation of ethylene to ethylene oxide, because a non-reactive material is essential for such applications [141]. However, aluminas are also important catalysts in their own right. Transition aluminas are known to catalyze the isomerization of alkenes, the dehydration of alcohols, H/D exchange reactions and C—H bond activation [142]. Consequently, the development of an understanding of both their bulk and their surface structure has been a key goal in catalysis, with solid-state NMR being widely employed to this end. 

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