Metal acidity

The arsenate(lll) ion can be reduced by systems which generate hydrogen (for example metal/acid) to give arsine, for example... 

The combination of alkali metal acid fluorides and porous aluminum fluoride IS a stable, solid, and efficient substitute for anhydrous hydrogen fluoride for promoting the ring-opening reactions of simple aliphatic oxiranes to give the fluorohydrins under sonication [/5] (equations 14 and 15)... 

Beiz-artikel, m. (Calico) mordant style, -bad, n. mordant bath, pickling bath, etc. (see Beize), behandlung, /. mordanting, pickling, etc. (see beizen). -briichigkeit, /. (Metal.) acid brittleness, -brtihe,/. (Leather) bate, drench, -biitte,/. (Leather) drench pit, bate tub. -charakter, m. (Dyeing) mordant character. 

Metall-salzUSsung, /. metallic-salt solution, -saure, /. metallic acid (as HMn04). -schlacke,/. metal slag, -schlauch, m. (flexible) metallic tube, metallic hose, -schliff,... 

It has already been indicated that titanium is not particularly resistant to corrosion in hot, strong acids of the type that usually generate hydrogen upon reaction with metals —acids such as sulphuric or hydrochloric. In contact with such acids, corroding titanium assumes a negative electrical potential (approximately -0-7 V, S.C.E.). 

The concept of simultaneous turn over between catalytic functions in multi-functional catalysis is widely accepted (for instance, in bi-functional metal/acid transformation of alkanes), and this aspect of the proposed mechanism is a normal behaviour in steady state. 

Accounting for these facts one should not be surprised coming across entirely different recommendations regarding the metal-acid-ethylene glycol ratio, which varies from 1-1.88-1.25 [5] or 1-4-1 [8] to 1-4.25-17.5 [7]. It is even sometimes noticed that a carboxylic acid and a poly hydroxy alcohol simply play the role of a fuel to bum a precursor and to form target oxides [16]. To shed some light on the aforementioned problems, the following steps could be of some help. 

Why are transition metals so well suited for catalysis A complete treatment of this critical question lies well beyond the scope of this book, but we can focus on selected aspects of bond activation and reactivity for dihydrogen and alkene bonds as important special cases. Before discussing specific examples that involve formal metal acidity or hypovalency, it is convenient to sketch a more general localized donor-acceptor overview of catalytic interactions in transition-metal complexes involving dihydrogen49 (this section) and alkenes (Section 4.7.4). 

Early investigations of the "forces of affinity" focused primarily on acid/base and metal/acid reactions, whereas Berthelot was to redefine affinity studies by focusing on organic systems and slow reactions. Berthelot, like the... 

Reducing Agents Hydrogen, lithium aluminum hydride, sodium borohy-dride, di-isobutyl aluminum hydride, iron metal Acids Sulfuric acid, hydrochloric acid, phosphoric acid, methanesulfonic acid, acetic acid, formic acid... 

After a short description of the main features of zeolites, the significant contribution of zeolite catalysts in green chemistry will be shown in examples of commercial or the potential processes of refining, petrochemicals, and fine chemicals involving acid or metal acid bifunctional catalysts. 

Acid and Bifunctional Metal/Acid Catalysis Active Sites... 

One-Pot Multistep Synthesis of Ketones on Bifunctional Zeolite Catalysts. One-pot multistep reactions constitute an elegant and efficient way to decrease the number of chemical and separation steps, hence, to develop greener synthesis processes. Bifunctional metal-acidic or metal-basic zeolite catalysts, which can be prepared easily with the desired properties (e.g., distribution of the... 

In addition to this, solid acid catalysts can also be used in the hydroisomerization cracking of heavy paraffins, or as co-catalysts in Fischer-Tropsch processes. In the first case, it could also be possible to transform inexpensive refinery cuts with a low octane number (heavy paraffins, n-Cg 20) to fuel-grade gasoline (C4-C7) using bifunctional metal/acid catalysts. In the last case, by combining zeolites with platinum-promoted tungstate modified zirconia, hybrid catalysts provide a promising way to obtain clean synthetic liquid fuels from coal or natural gas. 

Toxic Organic Chemicals Heavy Metals Acidity Heat... 

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