Application of hydrides

Sandrock, G., Hydrogen energy system production and utilization of hydrogen and future aspects, in Y. Yurum, Ed., Application of Hydrides, Kluwer Academic Publishers, Dordrecht, p. 253, 1995. 

Pesek, I.I., Matyska, M.T., Sandoval, J.E., and Williamsen, E.I., Synthesis, characterization and applications of hydride-based surface materials for HPLC, HPCE and electrochromatography, J. Liq. Chromatogr. Relat. Technol, 19, 2843, 1996. 

The domain of hydrides and complex hydrides is reduction of carbonyl functions (in aldehydes, ketones, acids and acid derivatives). With the exception of boranes, which add across carbon-carbon multiple bonds and afford, after hydrolysis, hydrogenated products, isolated carbon-carbon double bonds resist reduction with hydrides and complex hydrides. However, a conjugated double bond may be reduced by some hydrides, as well as a triple bond to the double bond (p. 44). Reductions of other functions vary with the hydride reagents. Examples of applications of hydrides are shown in Procedures 14-24 (pp. 207-210). 

SCHEME 13. Conversion of aldehydes into alkynes under homologation. Application of hydride shifts in vinylidene carbenoids... 

There are a number of engineering properties relating to practical applications of hydrides hysteresis, reversible capacity, decrepitation, activation, reaction kinetics, impurity tolerances, chemical stability, heat transfer, safety, cost and... 

Commercial applications of hydrides have become important and some of these compounds have become industrial chemicals manufactured and used on a large scale. 

Application of hydride heat machines (the HHM - the hydride heat pump (HHP), a refrigerator, a heat transformer, the compressor, the accumulator of hydrogen) is justified there where there are sources of low-potential energy or a plenty of wasted heat is not used. Systems hydrogen-metal hydrides promote improvement of ecological conditions and introduction of cleaner hydrogen technologies. 

C. Baluja-Santos, A. Gonzalez-Portal, Application of hydride generation to atomic-absorption spectrometric analysis of wines and beverages a review, Talanta, 39 (1992), 329-339. 

In the most elementary sense, a rechargeable metal hydride is a metal powder that can act as a solid "sponge" for hydrogen. In a chemical and practical sense, of course, the concept is a bit more complicated than that. In this paper we will present an introduction into the science and applications of rechargeable metal hydrides. It will consist of three parts (a) a review of the fundamentals and practical properties of metal hydrides, (b) a survey of the main families of rechargeable hydrides that are commercially available and, (c) a brief summary of the potential applications of hydrides within the existing hydrogen industry. 

Engineering Properties. In addition to the simple principles discussed above, there are a number of engineering properties that bear on practical applications of hydrides in the hydrogen storage, processing, and handling fields. Most of these are... 

Hysteresis, the pressure difference between absorption and desorption, should be small for most practical applications of hydrides. Hysteresis varies markedly from alloy to alloy in a manner not understood by researchers in the field. However, an empirical body of knowledge now exists to show a number of systems where hysteresis can be made quite small. The nickel-aluminum-mischmetal system (e.g., Figure 2) is a good example of one with small hysteresis. 

Experiments at KFA Julich have shown that H2 can be purified to greater than 99.9999% using a FeTi hydride tank(28). Separation of H2 from mixtures of 10-50% volume % H2 in CHi has been demonstrated using FexTiNii x alloys(29). The most important key to the successful application of hydrides for H2 separation and purification clearly will be the practical prevention of deactivation (poisoning) by the impurities present in the H2. 

Sandrock, G., Applications of hydrides, in Hydrogen Energy System, Utilization of Hydrogen and Future Aspects, Y. Yurum, Ed., NATO ASI Series, The Netherlands Kluwer Publishing, Dordrecht. 

Tavares, H.M.F., Vasconcelos, M.T.S.D., Machado, A.A.S.C., Silva, P.A.P., 1993. Application of hydride generation atomic absorption spectrometry to the determination of lead collected on air filters and sphagnum moss. Analyst 118, 1433-1439. 

GC is widely used to separate volatile organometallic species. The favored approach involves derivatization (e.g., ethylation or hydride formation), preconcentration, chromatographic separation followed by element-specific detection using AAS, AES, or AES. For species such as methylmercury and methylarsenic compounds, derivatization is normally necessary prior to GC in order to form volatile species. The most common approach has been to convert both inorganic and organometal species via hydridization with sodium borohydride, or alkylation, e.g., using sodium tetraethylborate, to form volatile hydrides or alkylated species, respectively. Not all species of an element are amenable to derivatization. For example, the application of hydridization... 

Nickel peroxide, which is readily obtainable, has proved to be a useful oxidation agent Permanganate oxidation is an effective general method for the conversion of aliphatic nitro into oxo compounds a,/3-Ethyleneketones as well as 1,4-naphthoquinones can be cheaply and safely epoxidized with hypochlorite A rapid direct preparation of peroxy acids in methanesulfonic acid has been published An efficient method for the oxidative removal of the methyl group in position 19 of steroids has been described The application of hydride transfer for carboxylations has been continued. 

The applicability of hydride generation to mercury speciation is limited because of the thermal instability of MeHgH, and the fact that inorganic mercury will be reduced to elemental mercury... 

Application of hydrides as reductants for coordinated carbonyl ligands... 

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