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Design and Synthesis of Helicene like Molecules
Bernard, Martin ; Sýkora, Jan ; Storch, Jan
Azahelicenes are unique inherently chiral three-dimensional aromatic compounds with high potential in homogenous assymetric catalysis. Their synthesis has many drawbacks and cannot be done in multigram scale so far. Recently, we have developed a route to new type of helicene-like molecules II. Multigram-scale synthesis of model compound where two benzene rings in [6]helicene skeleton are replaced by cyclopentadiene rings was accomplished in three steps. Such molecules have helical structure similar to helicenes, however, lower racemization barrier. Appropriately modified aza-analogues could be suitable catalysts for asymmetric reactions. Therefore, our synthetic approach leading to these compounds will be discussed.
Fulltext: content.csg - PDF Plný tet: 20120415230504 - PDF
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Characteristics of solid amalgam electrodes different from HMDE
Josypčuk, Bohdan ; Navrátil, Tomáš
In the contribution are shown the results of experiments realized with solid amalgam electrodes containing, apart from mercury, also Ag, Cu, Ir, Au, Bi, or Cd. These results differ from those obtained with the hanging mercury drop electrode (HMDE). In some cases the solid amalgam electrodes enable the study of properties of compounds, which can not be observed on HMDE, usually due to the anodic dissolution of mercury. Anodic stripping voltammetry of Zn(II), Cd(II), Pb(II), Cu(II), and Fe(III), cathodic stripping voltammetry of adenine, guanine, phytochelatins, sulfides, and catalytic processes in presence of hydrogen peroxide, alcohols and Os-modified DNA, were studied with the working amalgam electrodes.
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Carbosilane Dendrimers and Their Application in Catalysis
Krupková, Alena
his review summarizes the advances in synthesis, modification and utilization of carbosilane dendrimers with emphasis on their application in catalysis. Dendrimers with different cores, branching structure and functionality of end groups but containing only carbon and silicon atoms in their skeleton are considered. Dendrimers of this type are generally characterized by their excellent thermal and chemical stability together with high reactivity of end groups and versatility of their structure, which determines their large application potential.
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Lipolýza v superkritických tekutinách katalyzovaná enzymy
Bernášek, Prokop ; Sovová, Helena
In this work we investigated influences of some conditions on the conversion degree of lipase-catalysed ethanolysis of blackcurrant oil in supercritical carbon dioxide (SC-CO2). A continuous-flow reactor containing an immobilized enzyme was applied. The examined conditions were flow of SC-CO2 flow of ethanol, water content and geometrical adjustment of the reactor.
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Vliv parciální neutralizace na katalytickou aktivitu ionexů
Holub, Ladislav ; Hanková, Libuše ; Jeřábek, Karel
Concentration of acid centers in a commercional ion exchanger catalyst was controlled by partial neutralization of sulfonic groups with various primary, secondary and tertiary amines of different molecular size. The efect of acid centres concentration on the activity of ion exchanger catalyst was tested by measurements of initial reaction rate of reesterification of ethyacetate with methanol in a CSTR-type reactor. There was found that the slope of the dependence of the catalyrtic activity on the degree of the resin neutralization strongly depends on the amine basicity.
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