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Influence of catalysts on polyurethane formation
Chadima, David ; Petrůj, Jaroslav (referee) ; Kučera, František (advisor)
The bachelor thesis deals with the influence of catalysts on polyurethane formation. The theoretical part includes basic knowledge of polyurethane chemistry complemented by a literature review contains information about catalysis and reaction mechanism of polyurethane formation. In experimental part were studied effects of catalysts N,N,N',N' tetramethylethylenediamine, Stannous octoate, 1,4-Diazabicyclo[2.2.2]octane and Dibutyltin dilaurate at the rate of synthesis of the polyurethane resin. The measurement was based on measuring the time for which the reaction mixture reaches the maximum temperature. Effective concentrations of catalysts use were calculated. By additional measurement was performed simplified calculation of the activation energy for the demonstration of the effect of temperature on the observed reaction.
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Lanthanocene Catalysts for Synthesis of Polymers Applicable in Medicine
Slanina, Ondřej ; Kábelová, Božena (referee) ; Richtera, Lukáš (advisor)
The theoretic part of the thesis focuses on materials used in medicine. The metallic, ceramic, glass-ceramic and polymer materials are systematically described. The biocompatibility of the materials and possible threads of their usage for manufacturing of medicinal devices and implants are emphasized in the discussion. The work is focused especially on polymer materials. Different types of polymerizations are summarized with the accent on the preparation of biodegradable materials. In the practical part the synthesis of two organometallic bis(pentamethylcyclopentadienyl) sandwich complexes with holmium and gadolinium as a central atom designed for preparation of materials suitable for biomedicine is proposed.
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Design and adaptation of electron microscope accessories for in-situ experiments
Drozd, Michal ; Mikulík, Petr (referee) ; Kolíbal, Miroslav (advisor)
Účinnost katalyzátoru v kombinaci s optimalizovanou reakcí a minimalizováním jeho množsví jsou klíčovými faktory při snižování investičních a provozních nákladů v rámci chemických procesů. Díky pokročilým experimentálním technikám mohou být katalyzátory dále zlepšovány. Jednou z těchto technik je in-situ elektronová mikroskopie. Tato práce se zabývá vývojem zařízení pro automatický ohřev vzorku, automatickým vpouštěním reaktantů a měřením parciálních tlaků v komoře mikroskopu. Dále je pomocí provedených experimentů srovnán přístup pomocí environmentálního rastrovacího mikroskopu, kde se využívá laserový ohřev vzorku s přístupem, který využívá skenovací elektronový mikroskop připojený k ultra vakuové komoře, kde se vzorek zahřívá pomocí průchodu elektrického proudu.
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Synthesis of Lanthanidocene Based Compounds
Pospíšek, Marek ; Zmrzlý, Martin (referee) ; Richtera, Lukáš (advisor)
The aim of this bachelor thesis is to summarize the issues of the polymerization catalytic systems based on lanthanidocene complexes. These complexes are subsequently divided by the structure into four basic groups. One part of this work deals with an overview of the most interesting results of the catalytic systems, which are then analyzed and assessed either in its entirety or point of view of catalytic activity, living mechanism of polymerisation and stereo or regioselectivity. The focus is also placed on type of monomers or the conditions of polymerization. In this part of thesis are also described general methods for their synthesis. Found analogies and generalization are commented from the point of view of the design of the catalytic systems for the purpose of choosing the stereo or regioselectivity, molar mass and its distribution. This gives significance to these complexes as catalytic systems for obtaining the required polymer properties. The acquired knowledge is used for the theoretical design of the catalytic system for controlled polymerization.
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Decomposition of Volatile Organic Compounds in Gliding Arc Discharge
Grossmannová, Hana ; Kapička, Vratislav (referee) ; Pekárek,, Stanislav (referee) ; Krčma, František (advisor)
The aim of this thesis was to elaborate the issue of the decomposition of volatile organic compounds in the Gliding Arc plasma discharge at atmospheric pressure. Technologies based on nonthermal plasma could offer a good alternative to conventional techniques for the decomposition of volatile organic compounds, such as thermal and catalytic oxidation. Gliding Arc discharge (GidArc) is a widely exploited nonthermal plasma source used for many industrial applications, such as air-pollution control. The energy efficiency, reaction selectivity or production of specific species may be achieved in this kind of plasma, and thus for various chemical processes it can be much more effective then in conventional techniques. Presented experiments are linked to the previous results published in diploma thesis, which gave us the basics for construction of new reactor and optical emission spectroscopy measurements have been done to characterize the plasma. Toluene (aromatic, unsaturated), cyclohexane (aromatic, saturated) and hexane (aliphatic, saturated) were used as the model compounds for these experiments in the concentration range from hundreds to thousands ppm. Results focused on the electrical parameters of the reactor were carried out, with the aim to operate the system at a lower energy cost. In order to get the time-resolved diagnostics of the moving plasma channel, the evolution of the plasma channel was recorded continuously by using a high-speed video camera. In next part of the work, some results concerning generation of low molecular products like nitric oxide, nitrogen dioxide, hydrogen and carbon monoxide on the discharge conditions are presented. In combustion process, undesirable mixture of toxic highmolecular by-products can be formed. Samples were therefore analysed in gas chromatograph linked to mass spectrometer, to characterize the chemical transformation pathway of VOC in plasma.
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Catalytic and photochemical cycloadditions of alkynes
Fadeev, Aleksandr ; Kotora, Martin (advisor) ; Pour, Milan (referee) ; Parkan, Kamil (referee)
Novel approaches to utilizing alkynes in transition metal-catalyzed [2+2+2] cycloadditions and photochemical [2+2] cycloadditions were investigated with respect to the potential applications of these transformations. First, a chemo- and regioselective fully intermolecular cocyclotrimerization of internal alkynes with a commercially available ethynyl boronate was developed using Ru-catalysis and its mechanism was examined using DFT calculations. The established method allows for a straightforward preparation of various 1,4-diborylated benzenes, which can serve as multifunctional building blocks in organic synthesis. In particular, the products can be used in cross-coupling, carbonylation and oxidation reactions to access a broad variety of contiguously substituted arenes, such as natural products mirandamycin and violaceoid C. Second, a comparative study of catalytic and uncatalyzed photocycloadditions between alkynes and quinones was undertaken. Contrary to the recent reports, irradiation with visible light alone is sufficient to obtain not only the [2+2] cycloaddition products, but also several products of cascade transformations. Thus, depending on the structure of the quinone used, either carbo- or heterocycloaddition pathway is mainly realized, giving rise either to annulated cyclobutenes or...
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Synthesis of Alkaloid-like Compounds with Quaternary Carbon Centers
Jansa, Petr ; Matoušová, Eliška (advisor) ; Baszczyňski, Ondřej (referee) ; Nováková, Veronika (referee)
Synthesis inspired by natural products has a long tradition in drug development. Because the structure of bioactive natural compounds is often very complex, preparation of their derivatives requires the development of specific synthetic procedures. This thesis focuses on derivatives of certain alkaloids from the Amaryllidaceae plant family as examples of such compounds. The thesis explores the possibilities of preparing polycyclic compounds that contain the structural motif present in tazettine, crinine, or mesembrine-type alkaloids. This motif includes a quaternary all-carbon center, for which a method involving a tandem cyclization/Suzuki coupling reaction and a halocarbocyclization was developed and optimized in this work. The scope of these reactions was studied, and variously substituted products containing oxygen and nitrogen cycles were prepared. Furthermore, methods for the synthesis of N-alkylated derivatives, dehydrohalogenation to form a double bond, or various mainly oxidative modifications of the cycle adjacent to the aromatic ring were developed. After developing a method for the preparation of enantiomerically enriched starting material, an asymmetric version of the entire synthesis was successfully performed. Finally, biological properties of selected compounds were studied. Some...
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Influence of bases on heterogeneous Lewis acid catalyzed hydrogen transfer reactions
Veselá, Klára ; Přech, Jan (advisor) ; Bulánek, Roman (referee)
Heterogeneous Lewis acid zeolites catalyzed Meerwein-Ponndorf-Verley (MPV) reduction (transfer hydrogenation), where ketones and aldehydes are reduced to the corresponding alcohols. The hydrogen is taken from a secondary alcohol. These Lewis acid zeolite catalysts have a great advantage over homogenous catalysts as they are well separable from the reaction mixture and recyclable. Lewis acid zeolites are materials that contain incorporated tin or zirconium species, which act as Lewis acid sites. MPV reduction of citronellal provides citronellol as a product. However, the reaction of citronellal with 2- propanol also proceeds via a parallel reaction pathway providing isopulegol as the major product. Addition of pyridine (an organic base) to the reaction mixture switches the selectivity of the reaction, i.e., citronellol becomes the main product of the cited citronellal reaction with 2-propanol. It was investigated whether this phenomenon would also be observed for reactions with the addition of different bases. To answer these questions, Sn-BEA and Zr-BEA were prepared by hydrothermal synthesis. Impreg-Zr-BEA and impreg-Sn-BEA were prepared by postsynthesis metal incorporation. In addition, highly porous 2D Self-pillared pentasil zeolites containing tin and zirconium were hydrothermally synthesized....
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The effect of substituents, structure of the reactant and type of active sites on the reaction rate and selectivity of cyclization reactions
Živný, Marek ; Veselý, Ondřej (advisor) ; Bulánek, Roman (referee)
Tetrahydropyrans (THPs) are valuable compounds in the synthesis of pharmaceuticals and fragrances. Currently, THPs are most commonly synthesized using the Prins cyclisation, hetero-Diels-Alder reaction and oxy-Michael reaction. These reactions are undesirable because they use catalysts based on heavy metals and strong acids, which are harmful to the environment. In this thesis, we investigated the synthesis of THPs with the aim of replacing toxic heavy metals and strong acids with more benign catalysts, such as zeolites. Zeolites are microporous crystalline metallosilicates, which are commonly used as catalysts due to their high acidity, selectivity and stability. Previous research has successfully shown that zeolites can catalyse THP synthesis through cyclisation of unsaturated alcohols and determined the effect of pore size on catalytic activity. In contrast, this work aimed to examine zeolites with different framework elements, which introduce diverse types of acid sites. Additionally, we aimed to investigate the impact of functional groups present in the structure of the reactants, specifically functional groups with either electron-donating (EDG) or electron-withdrawing (EWG) effects and with different aromatic cycle systems. We chose (E)5-phenyl-4-pentenol as the primary reactant for the cyclisation....
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Synthesis and Reactivity of Enynes with Terminal Double Bond
Grobař, Bartoloměj ; Matouš, Petr (advisor) ; Opálka, Lukáš (referee)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of organic and bioorganic chemistry Candidate: Bartoloměj Grobař Supervisor: PharmDr. Petr Matouš, Ph.D. Title of thesis: Synthesis and reactivity of enyns with terminal double bond This work focuses on synthesis of structures containing terminal vinyl moiety and their subsequent reactivity. We tested various approaches that lead to formation of enynes, which are then cyclized using gold complex catalyst into tetrahydropyridines. Both utilize the addition of propargylamine protected by 4-methoxybenzenesulfonyl group to substituted butynone and methoxyphenyl propiolates. Tetrahydropyridine molecules that are successfully created, are further derivatized forming polycyclic structures.
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