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Homogeneous and heterogeneous titanium complexes and their use for selective ethylene trimerization to 1-hexene
Hodík, Tomáš ; Pinkas, Jiří (advisor) ; Merna, Jan (referee)
This diploma thesis is focused on the design and synthesis of new half-sandwich titanium complexes for anchoring to selected supports (SiO2, SBA-15) and the study of their catalytic activity and selectivity in ethylene trimerization to 1-hexene. The synthetic strategy of half-sandwich titanium complexes with a suitable leaving group for direct anchoring through Ti−O bond was carried out (Cl, Oi-Pr). In addition, the titanium complexes with pendant alkenyl group were prepared and utilised for anchoring to a SiMe2H modified support by Pt-catalysed hydrosilylation reaction. Prepared compounds were characterised by standard spectroscopic methods (IR, NMR, MS). The heterogeneous systems were characterised by MAS NMR and IR spectroscopy, powder XRD, ICP-OES, TGA and the textural parameters were determined from nitrogen adsorption/desorption isotherms. For all prepared materials was studied the catalytic activity for ethylene trimerization and the selectivity to 1-hexene.
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Phosphinoferrocene ligands with polar amide substituents
Charvátová, Hana ; Štěpnička, Petr (advisor) ; Trávníček, Zdeněk (referee) ; Jambor, Roman (referee)
Title: Phosphinoferrocene ligands with polar amide substituents Author: Hana Charvátová Department: Department of Inorganic Chemistry Supervisor: prof. RNDr. Petr Štěpnička, Ph.D. Abstract: This thesis is focused on phosphino-urea ferrocene ligands that are still rather neglected in the literature. It describes the synthesis of novel polar amides and hydrazides of 1'-(diphenylphosphino)ferrocene-1-carboxylic acid (Hdpf) with or without ethylene linker bearing various urea and guanidine terminal functional groups. Urea and guanidine derivatives with ethylene bridge can be prepared from Hdpf and appropriate amine with amidation agents. Phosphine ureas without the linker are accessible from reactions of primary amide of Hdpf with suitable acylation agents while analogical guanidine is obtained from guanylation of amide-amine generated from Hdpf acylbenzotriazole and ethylenediamine. Reaction of the acylbenzotriazole with free guanidine leads to [1-(diphenylphosphino)ferrocenecarbonyl]guanidine hydrochloride. These ferrocene ligands were used to prepare four types of palladium(II) complexes, viz. where L denotes the newly synthesized ligands and LNC is 2- [(dimethylamino)methyl]phenyl-C,N auxiliary chelating ligand. Catalytic efficiency of complexes with ethylene bridge was tested on reactions of aromatic...
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Study of physical and chemical properties of surface-modified tungsten oxide
Polášek, Jan ; Mašek, Karel (advisor)
Title: Study of physical and chemical properties of surface-modified tungsten oxide Author: Jan Polášek Department: Department of Surface and Plasma Science Supervisor: Doc. RNDr. Karel Mašek, Dr., Department of Surface and Plasma Science Abstract: This work can be divided into two parts. In the first part, we examine possibilities of preparation of monocrystalline tungsten and tungsten oxide na- noclusters by means of magnetron sputtering with gas aggregation. Clusters are prepared in the non-reactive (Ar) and reactive (Ar + O2) atmosphere and heated after the deposition or during the flight by IR radiation. Influence of oxygen in the aggregation process was described and possibilities of generating crystalline tungsten and tungsten oxide clusters were found. In the second part, we study reactivity of tungsten oxide layers, pure and doped with rare metals (Pt, Au), deposited on the silicon wafer and etched carbon, towards partial methanol oxi- dation. Influence of carbon substrate and metal doppants on reactivity was found and described, along with mofrological and chemical changes that occurs in the sample during the proces. Keywords: catalysis, tungsten oxide, clusters, partial oxidation of methanol, etched carbon 1
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Synthesis of cycles using organocatalysis and catalysis with metal complexes
Hurný, David ; Veselý, Jan (advisor) ; Trnka, Tomáš (referee)
This thesis deals with an enantioselective synthesis of cyclic compounds by using a combination of organocatalysis and transition metal catalysis. The thesis deals mainly with usage of aminocatalyst for activation of aldehydes and copper catalyst for activation of terminal triple bond. The first part is focused on the preparation of starting compounds for cyclizations (α-oxoesters, α- substituted nitroalkanes and α-substituted aldehydes). The second part concerns carbocyclization itself and optimization of reaction conditions to achieve highly stereoselective reaction. Powered by TCPDF (www.tcpdf.org)
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Effect of silver in homogeneous gold catalysis
Motloch, Petr ; Roithová, Jana (advisor) ; Hocek, Michal (referee)
Gold catalysis has recently experienced a sustained upswing in interest from scientific community. The amount of new reactions catalysed by gold is so significant that little is known about mechanisms of most of these reactions. Research into mechanisms of (not only) gold catalysed reactions is therefore very significant area of interest and important to the continued improvement of gold catalysed reactions. Formation of cationic π-complexes is considered a first mechanistic step in reactions catalysed by gold(I). The bond dissociation energies of gas phase cationic π-complexes were investigated by mass spectrometry and theory calculations in this thesis. These complexes consisted of differently substituted unsaturated hydrocarbons (alkenes, alkynes, alkadienes and allenes) and complex cations of silver and gold containing second ligand (triphenylphosphine, acetonitrile). On the basis of the results obtained from this study, a possible origin of the "silver effect" in gold(I) catalysis is discussed. Key words catalysis, gold, silver, mass spectrometry, DFT calculations, reaction intermediates
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Electronics and adsorption properties of model catalytic systems contains cerium
Cabala, Miloš ; Veltruská, Kateřina (advisor) ; Jiříček, Petr (referee) ; Polčík, Martin (referee)
Title: Electronics and adsorption properties of model catalytic systems contains cerium Author: Miloš Cabala Department: Department of Surface and Plasma Science, Supervisor: RNDr. Kateřina Veltruská, Department of Surface and Plasma Science, Abstract: The doctoral thesis contains the study of model catalyst systems based on cerium and ceria. The thesis deals with model systems of CeAg, CeO2/Cu(111), Ni- CeO2/Cu(111) a Ni-Sn-CeO2/Cu(111). We have studied these systems using photoelectron spectroscopy, ion scattering spectroscopy and low energy electron diffraction. Model systems were prepared under strictly defined conditions. The strong bimetallic interaction was observed on the CeAg layers. Molecular adsorption of carbon monoxide on CeAg was demonstrated. We also observed intensive reaction of these layers with oxygen. By measurements in different directions of surface Brillouin zone, we managed to reconstruct the band structure of the prepared CeO2/Cu(111) layer. We have shown that the Cu substrate interacts weakly with deposited CeO2 layer. This interaction results in a charge transfer from Cu into CeO2. Overall, in the valence spectrum we have identified three main electron bands corresponding to O 2p state bound in CeO2. It has been proven that the deposition of Ni on CeO2 layers leads to partial...
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Preparation and properties of building blocks of specialty polymers
Šichová, Kristýna ; Svoboda, Jan (advisor) ; Sedláček, Jan (referee)
This Diploma Thesis presents results obtained by solution of two partial projects: a) Preparation of monomers from renewable sources using metathesis and tandem hydrogenation catalyzed with ruthenium compounds - project solved during my Erasmus stay at the Université de Rennes 1 in France; b) Preparation and properties of ,-bis(tpy)quarterthiophene oligomers carrying ionic side groups as oligomonomers for polyelectrolyte conjugated dynamers - project solved at the Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague. Project a): Self-metathesis of 1,2-epoxyhex-5-ene (but-3-enyloxirane) and its cross-metathesis with methyl acrylate and acrylonitrile catalyzed with ruthenium compounds as well as tandem design of these metatheses and consecutive hydrogenation of their products by gaseous hydrogen have been optimized. The following influences have been studied and tuned: (i) type of the catalyst (Grubbs, Hoveyda, Zhan) and its concentration and method of dosing, (ii) concentration of reactants and additives, (iii) type of solvent, and (iv) reaction temperature. Reactions were monitored by the GC, GC and MS methods and the products were characterized by the NMR method. Methyl 6,7-epoxyheptanoate (methyl 5-oxiranylpentanoate) obtained by the tandem...
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Theoretical Investigation of Mechanisms of Chemical Reactions Taking Place in Microporous Materials
Položij, Miroslav ; Nachtigall, Petr (advisor) ; Pulido Junquera, María Ángeles (referee)
Mechanisms of three reactions catalyzed by microporous materials were investigated computationally; the reactions investigated include Friedländer and Knoevenagel reactions catalyzed by Cu3BTC2 metal organic framework (MOF) and an intramolecular cyclisation of unsaturated alcohols catalyzed by zeolite H-ZSM-5. It was found that the reaction mechanisms of all three reactions are controlled by a high concentration of active sites in materials. Reaction intermediates interact with more than one active site simultaneously. This novel concept of "multiple-site" interactions is described. The concerted effect of two catalytic sites leads to a decrease of activation barriers on reaction paths of Friedländer and Knoevenagel reactions. On the contrary, a simultaneous interaction of reactants with two active sites has a negative effect on reaction rate in case of alcohol cyclization catalyzed by H-ZSM-5; it was found that the interaction with dual sites results in the increase of activation barriers and diffusion limitations. In case of Knoevenagel reaction catalyzed by CuBTC, the adsorption of reaction precursor to the reaction site allows the creation of a dynamic defect in the MOF framework that subsequently catalyses the reaction. Both, the multiple sites effect and the dynamical defect formation effect...
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