Synthesis with various catalysts, specific

The raw material for the synthesis was methane. Powder of Nickel carbonyl (NC) or powder of nano-diamond (ND) was the catalyst. Attempts to synthesize pyro-carbon on copper powder were not successful. Powder with the composition 70%PC, 30%NC, and also the set of powders with various ratios of PC and ND were tested. Anodes made of the powder 70PC30NC showed satisfactory cycle behavior and had specific capacity 180 mAh/(g of powder) (260 mA-h/(g 0f carbon)) (Fig. 3a). The anodes made of powder xPCyND, irrespective of the components ratio, had specific capacity... 

The synthesis of the disaccharide subunit 85 of tricolorin A, a cytotoxic resin glycoside isolated from lpomoea tricolor, provides a unique opportunity to compare the efficiency of an RCM-based macro cyclization reaction with that of a more conventional macrolactonization strategy. Furthermore, this specific target molecule challenges the compatibility of the catalysts with various functional groups. 

This chapter is concerned specifically with olefin metathesis reactions catalyzed by ruthenium-carbene complexes, mainly because of their great success during recent years. We begin with an overview of these catalysts, and then focus on mechanistic considerations that are important for understanding the reactivity profiles of various catalyst derivatives. The second part of the chapter deals with applications of ruthenium-catalyzed olefin metathesis, especially RCM, CM, and combination processes in organic synthesis. 

Whereas many metal complexes can be generated in situ, the synthesis and application of discrete catalysts provides a number of distinct advantages. With a well-defined structure, various catalysts can be fine-tuned to meet the needs of specific applications. 

The synthesis of 5-arylthianthrenium salts, 8, [CRI 02a, CRI 04] can be carried out by the condensation of thianthrene-S-oxide with various aromatic compounds bearing electron-donating substituents, R, as depicted in equation [2.1], A mixture of methanesulfonic acid and phosphorous pentoxide serves as an acid catalyst and dehydrating agent for this reaction. Replacement of the methanesulfonate anion by a metathetical reaction with NaMtXn affords the desired active photoinitiator, 8. Depending on the specific R substituent, 5-arylthianthrenium photoinitiators have UV absorption maxima in the range of 300-400 nm. 

Generally, native enzymes never dissolve in organic solvents. We have reported that PEG-modified enzymes dissolved not only in various organic solvents but also in hydrophobic substrates and can be used as catalysts in chemical reactions in these hydrophobic media. These reactions proceed under very mild conditions, which enable us to apply PEG-enzymes to various organic syntheses of unstable or chiral compounds. Moreover, the enzymic reactions with high substrate specificity are suitable for the synthesis of various useful compounds. 

The lure of new physical phenomena and new patterns of chemical reactivity has driven a tremendous surge in the study of nanoscale materials. This activity spans many areas of chemistry. In the specific field of electrochemistry, much of the activity has focused on several areas (a) electrocatalysis with nanoparticles (NPs) of metals supported on various substrates, for example, fuel-cell catalysts comprising Pt or Ag NPs supported on carbon [1,2], (b) the fundamental electrochemical behavior of NPs of noble metals, for example, quantized double-layer charging of thiol-capped Au NPs [3-5], (c) the electrochemical and photoelectrochemical behavior of semiconductor NPs [4, 6-8], and (d) biosensor applications of nanoparticles [9, 10]. These topics have received much attention, and relatively recent reviews of these areas are cited. Considerably less has been reported on the fundamental electrochemical behavior of electroactive NPs that do not fall within these categories. In particular, work is only beginning in the area of the electrochemistry of discrete, electroactive NPs. That is the topic of this review, which discusses the synthesis, interfacial immobilization and electrochemical behavior of electroactive NPs. The review is not intended to be an exhaustive treatment of the area, but rather to give a flavor of the types of systems that have been examined and the types of phenomena that can influence the electrochemical behavior of electroactive NPs. 

One of the important applications of mono- and multimetallic clusters is to be used as catalysts [186]. Their catalytic properties depend on the nature of metal atoms accessible to the reactants at the surface. The possible control through the radiolytic synthesis of the alloying of various metals, all present at the surface, is therefore particularly important for the catalysis of multistep reactions. The role of the size is twofold. It governs the kinetics by the number of active sites, which increase with the specific area. However, the most crucial role is played by the cluster potential, which depends on the nuclearity and controls the thermodynamics, possibly with a threshold. For example, in the catalysis of electron transfer (Fig. 14), the cluster is able to efficiently relay electrons from a donor to an acceptor, provided the potential value is intermediate between those of the reactants [49]. Below or above these two thresholds, the transfer to or from the cluster, respectively, is thermodynamically inhibited and the cluster is unable to act as a relay. The optimum range is adjustable by the size [63]. 

Microreactor technology offers the possibility to combine synthesis and analysis on one microfluidic chip. A combination of enantioselective biocatalysis and on-chip analysis has recently been reported by Beider et al. [424]. The combination of very fast separations (<1 s) of enantiomers using microchip electrophoresis with enantioselective catalysis allows high-throughput screening of enantioselective catalysts. Various epoxide-hydrolase mutants were screened for the hydrolysis of a specific epoxide to the diol product with direct on-chip analysis of the enantiomeric excess (Scheme 4.112). 

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