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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
741

Designing for sustainability: applications of tunable solvents, switchable solvents, and catalysis to industrial processes

Fadhel, Ali Zuhair 06 January 2011 (has links)
The focus of this research was to improve the sustainability of various processes by employing tunable solvents, switchable solvents, and catalysis. In Chapter 2, we report applications of tunable solvents to metal and enzyme catalyzed reactions of hydrophobic substrates. Tunable solvents are defined as solvent that change properties rapidly but continuously upon the application of an external physical stimulus and we utilize these solvents to couple homogeneous reactions with heterogeneous separations. We developed organic-aqueous tunable solvents that utilize propane for efficient phase separation at moderate pressures around 1 MPa; for example the water contents in the propane-expanded THF is 3 wt% at 0.8MPa at 30°C. Also, we extended the use of CO2-organic-aqueous tunable solvents to a pharmaceutically-relevant reaction--the hydroformylation of p-methylstyrene. The homogeneous reactions provide fast rates with excellent yields. At 60°C, the reaction reaches completion after 180 minutes with 95% branched aldehyde yield. The CO2-induced heterogeneous separation of the product from the catalyst provides an efficient and simple way to remove 99% of the product, to retain 99.9% of catalyst, and to recycle the Rh-TPPMS catalyst for five consecutive reactions. In chapter 3, we investigated the use of reversible ionic liquids (RevILs) for synthesis of nanoparticles. RevILs are formed by the reversible reaction of compounds with basic nitrogen functionalities (molecular liquid) with CO2 at ambient pressure to form a liquid salt (ionic liquid). We demonstrated that RevILs form microemulsions that can be switched-on by bubbling CO2 and switched-off by heating. These microemulsions solubilize ionic compounds such as chloroauric acid. We utilized these microemulsions as a template for controlled synthesis of gold nanoparticles. With 2-component RevILs, [TMBGH]+[O2COCH3]-/N-propyl-octylsulfonamide/hexane were used to form particles in the size range of 6-20 nm with an average particles size of 11.4±3.3. With 1-component RevILs, (3-aminopropyl)-tripropylsilane was used to prepare semi-spherical gold particles with an average size of about 20nm. The 1-component RevILs systems provide a simpler method to form microemulsions when compared to the 2-componenet RevILs systems since they eliminate the need for alcohols and surfactants. In chapter 4, we developed a catalyst that efficiently decomposes hydrazine to selectively produce ammonia. This enables the use of the chemical propulsion hydrazine for electric propulsion as well. We prepared nickel, copper, cobalt, ruthenium, rhodium, and iridium nanoparticles that were supported on silica and we tested these silica-supported metals for the decomposition of hydrazine. To study the catalytic activity, we designed and constructed a continuous flow reactor. The results show that nano-nickel supported on silica is the most active and selective catalyst with 100% conversion of hydrazine and 94±3% yield of ammonia.
742

Physical models and computational algorithms for simulation of full-scale catalytic monolithic reactors

Kumar, Ankan, January 2009 (has links)
Thesis (Ph. D.)--Ohio State University, 2009. / Title from first page of PDF file. Includes bibliographical references (p. 239-251).
743

Organometallic catalysis in aqueous solution : reactions and mechanisms of water-soluble molybdocenes /

Breno, Kerry L., January 2004 (has links)
Thesis (Ph. D.)--University of Oregon, 2004. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 213-252). Also available for download via the World Wide Web; free to University of Oregon users.
744

Studies on asymmetric reactions and catalysis using axially chiral 2-substituted N, N-dialkyl-1-naphthamides and p-chiral secondary phosphine oxides /

Yeung, Ka Yim. January 2003 (has links)
Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 196-207). Also available in electronic version. Access restricted to campus users.
745

Design of new ligands for asymmetric catalysis /

Tong, Ka Pui. January 2003 (has links)
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 107-111). Also available in electronic version. Access restricted to campus users.
746

Catalytic activity of transition metal halides : dehydrochlorination of tert-butyl chloride /

Leung, Ka-sing, January 1980 (has links)
Thesis--Ph. D., University of Hong Kong, 1981. / Cover title.
747

Asymmetric Nitrene Transfer Reactions with Azides via Co(II)-Based Metalloradical Catalysis (MRC)

Tao, Jingran 01 January 2013 (has links)
Asymmetric nitrene transfer reactions via metalloradical catalysis (MRC) with azides has attracted research interest because of its fundamental and practical importance. The resulting nitrogen-containing units are recurrent motifs in biologically important molecules and can serve as versatile precursors in organic synthesis. The [Co(D2-Por*)] have emerged as a new class of catalysts for asymmetric aziridination and C-H amination. These metalloradical catalysts have been shown to be highly effective for the asymmetric intermolecular aziridination of a broad scope of substrates with different classes of azides with excellent to good enantioselectivity. The intramolecular C-H amination utilizing various azides can allow for the construction of diverse nitrogen containing heterocyclic compounds.
748

Computational Methods in Medicinal Chemistry : Mechanistic Investigations and Virtual Screening Development

Svensson, Fredrik January 2015 (has links)
Computational methods have become an integral part of drug development and can help bring new and better drugs to the market faster. The process of predicting the biological activity of large compound collections is known as virtual screening, and has been instrumental in the development of several drugs today in the market. Computational methods can also be used to elucidate the energies associated with chemical reactivity and predict how to improve a synthetic protocol. These two applications of computational medicinal chemistry is the focus of this thesis. In the first part of this work, quantum mechanics has been used to probe the energy surface of palladium(II)-catalyzed decarboxylative reactions in order to gain a better understating of these systems (paper I-III). These studies have mapped the reaction pathways and been able to make accurate predictions that were verified experimentally. The other focus of this work has been to develop virtual screening methodology. Our first study in the area (paper IV) investigated if the results from several virtual screening methods could be combined using data fusion techniques in order to get a more consistent result and better performance. The study showed that the results obtained from data fusion were more consistent than the results from any single method. The data fusion methods also for several target had a better performance than any of the included single methods. Next, we developed a dataset suitable for evaluating the performance of virtual screening methods when applied to large compound collection as a replacement or complement for high throughput screening (paper V). This is the first benchmark dataset of its kind. Finally, a method for using computationally derived reaction coordinates as basis for virtual screening was developed. The aim was to find inhibitors that resemble key steps in the mechanism (paper VI). This initial proof of concept study managed to locate several known and one previously not reported reaction mimetics against insulin regulated amino peptidase.
749

Novel N-heterocyclic carbene architectures for use in carbene based polymers and redox swithcable : catalysis / Novel N-heterocyclic carbene architectures for use in carbene based polymers and redox switchable catalysis

Kamplain, Justin Wade, 1980- 13 September 2012 (has links)
The central focus of this dissertation pertains to the synthesis and study of novel N-Heterocyclic carbene architectures. This pursuit has led to advances in carbine structure and bonding, and application of NHCs in materials chemistry in the role of monomer and catalyst / text
750

Development of ruthenium catalyzed hydrogenative carbonyl addition reactions

McInturff, Emma Leigh 30 June 2014 (has links)
Metal-catalyzed, hydrogenative methods for carbon-carbon bond formation are attractive alternatives to traditional carbonyl addition reactions. Through in situ generation of aldehyde and organometallic species, these redox-triggered reactions circumvent the need for preactivation of reactive partners, thereby providing a more atom economic, efficient approach to carbonyl addition products. Efforts have been focused on the development of ruthenium-catalyzed coupling reactions of primary and secondary alcohols to basic feedstock chemicals and easily accessible and stable unsaturated compounds. To perform highly stereoselective reactions, investigation into the factors that control stereoselectivity in ruthenium catalyzed transfer hydrogenative couplings was undertaken. As a critical tool for the construction of organic molecules, modernizing methods for carbonyl addition can contribute to the evolution of synthetic organic methodology. / text

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