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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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Ferrocene stibane ligands
Antala, Jakub ; Štěpnička, Petr (advisor) ; Gyepes, Róbert (referee)
5 Title: Ferrocene stibane ligands Author: Jakub Antala Department: Department of Inorganic Chemistry Supervisor: prof. RNDr. Petr Štěpnička, Ph.D., DSc. Abstract: This diploma thesis reports a study into the coordination properties of ferrocene phosphino-stibine Cy2PfcSbPh2 (LCy, Cy = cyclohexyl, fc = ferrocene-1,1'-diyl). Complexes with various transition metals were prepared (RuII , RhIII , PtII , PdII , AuI ), where the ligand binds in monodentate, bridging or chelating mode. Ruthenium(II) and rhodium(III) complexes were prepared from precursors with π-coordinated arene ligands, whereas [MCl2(η2 :η2 cod)] (M = Pd, Pt; cod = 1,5-cyclooctadiene) precursors were used to prepare palladium(II) and platinum(II) complexes and synthesis of gold(I) complexes started from [AuCl(tht)] (tht = tetrahydro- thiophene). In addition, the thesis describes the reactivity of ferrocene phosphino-stibine Ph2PfcSbPh2 (LPh). Specifically, it focuses on the preparation of chalcogenides Ph2P(E)fcSbPh2 (E = O, S, Se) and the corresponding stiborane derivatives Ph2P(E)fcSbPh2(O2C6Cl4) (E = void, O, S, Se), in which the stiborane center bears tetrachloropyrocatechol substituent, which makes it Lewis acidic and potentially prone to behave as an acceptor of electron pair from the Ph2P(E) moiety. The presence of this interaction was...
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