Metal laboratory-scale synthesis

New nanocortposites on the basis of metal oxides and mesoporous Ti-silicates were developed and characterized by a set of physical-chemical analysis. The original laboratory scale synthesis technology for manufacture of such materials includes the combination of the following methods the template method, the methods of microemulsions and microsuspensions. 

Borazine originally was obtained by the reaction of ammonia with diborane.1 Mixtures of lithium or sodium tetrahydro-borate with ammonium chloride also have been pyrolyzed to yield this product.2 More recently, the reduction of B,B, B"-trichloroborazine with alkali metal hydroborates has proved to be a convenient laboratory-scale method for the preparation of this compound.3-7 The procedure described herein is a variation of the last method as reported by Dahl and Schaeffer.7 This method is effective for the synthesis of iV-substituted alkyl- and arylborazines, i.e., compounds of the formula (HBNR)3 where R is CH3, C2H6, C6H , C6H5, p-C6H4CH3, or p-C6H4OCH3.5... 

Concerning the Fischer-Tropsch synthesis, carbon nanomaterials have already been successfully employed as catalyst support media on a laboratory scale. The main attention in literature has been paid so far to subjects such as the comparison of functionalization techniques,9-11 the influence of promoters on the catalytic performance,1 12 and the investigations of metal particle size effects7,8 as well as of metal-support interactions.14,15 However, research was focused on one nanomaterial type only in each of these studies. Yu et al.16 compared the performance of two different kinds of nanofibers (herringbones and platelets) in the Fischer-Tropsch synthesis. A direct comparison between nanotubes and nanofibers as catalyst support media has not yet been an issue of discussion in Fischer-Tropsch investigations. In addition, a comparison with commercially used FT catalysts has up to now not been published. 

Conversely, other processes are totally original. This is especially encountered when the electrochemical act is associated with a transition metal complex catalysis. These methods have the advantage of affording the organozinc compound synthesis under simple and mild conditions that are compatible with the presence of reactive functional groups on the substrate. Importantly, these procedures are reproducible and can be run by any chemist. Besides, the preparation from a few millimoles to tens of millimoles of the organometallic compound is easy at the laboratory scale. 

The following procedure is an operatively simple route for the synthesis of bromotrimethylsilane on a preparative laboratory scale from reagents that are readily accessible and inexpensive. This could be a method of choice in some laboratories despite the fact that bromotrimethylsilane is now commercially available (Petrach Systems, Aldrich, or Alpha). Moreover, the procedure also serves as a suitable method for the synthesis of azidotrimethylsilane and isocyanatotrimethylsilane, and is specially useful for the preparation of cyanotrimethylsilane. Thus a mixture of triphenylphosphine dibromide, hexamethyldisiloxane, and a catalytic amount of powdered metal zinc in 1,2-dichlorobenzene is heated under reflux to produce bromotrimethylsilane in nearly quantitative yield, which is simultaneously distilled over a suspension of the corresponding pseudohalogenoacid salt in N, /V-dimethylformamide as solvent.6... 

Metal- and alloy-containing membranes are currently applied mainly in ultrapure hydrogen production. Pilot plants with palladium alloy tubular membrane catalyst were used in Moscow for hydrogenation of acetylenic alcohols into ethylenic ones. In the Topchiev Institute of Petrochemical Synthesis, a laboratory-scale reactor of the same type was tested... 

A variety of metal compounds as an oxidant have long been used for phenolic oxidation. These oxidants are widely used and are very effective for organic synthesis in a laboratory scale. However, they are no longer utilized in an industrial scale, because stoichiometric amounts of these metal compounds are often required. Accordingly, the corresponding oxidation-reduction systems must be constructed for each metal oxidation. In this section, phenolic oxidation using a variety of metal compounds will be described. 

The synthesis of R3AI via the historic reaction of R2Hg (high toxicity) with xs Al metal is still useful on a small laboratory scale (R = n-alkyl) ... 

Among transition metal catalysts, palladium-centered transformations are found to be most versatile, with a wide range of applications on both industrial and laboratory scales [1]. As a result of the growing importance of cross-coupling reactions in organic synthesis over the past few decades, Pd-catalyzed C-X (X=C, N, O, S) bond formation has emerged as an intensively studied area... 

There are two different approaches for the production of enantiomers asymmetric synthesis and racemate resolution. The first, in special cases, allows a favourable production as costs are concerned, e.g. in case of the asymmetric hydrogenation of double bonds by use of optimized chiral transition metal complexes. In most cases, however, asymmetric syntheses, especially multi-step ones, are restricted to the laboratory scale. 

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