Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 74 for “"phase transfer"”.
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Surfactant assisted phase transfer of water-insoluble quantum dots
… the role of surfactants in facilitating the phase transfer of hydrophobic nanomaterials from organic solvents into the aqueous phase. Without surfactants, hydrophobic nanomaterials would aggregate into micro-scale aggregates in water, potentially reducing their bio-availability, mobility, and …
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Reversible Directed Phase Transfer of M4IIL4 and M4IIL6 Cages
… their ability to move between different solvent phases upon heating was investigated. A capsule-mediated transport system as developed that is both directional and reversible. The flow of the capsule and its encapsulated cargo is directed using stimuli such as temperature modification. Ultimately …
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Phase transfer catalysis: catalyst screening, reaction development, and mechanism analysis
… of a [2,3]-Wittig rearrangement under phase transfer catalysis (PTC) reaction conditions was investigated. Supplementing these studies, a deeper understanding of the PTC mechanism was sought for the alkylation of phenol. In regards to the asymmetric PTC (APTC) alkylation, a small …
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Phase transfer in a collision between a droplet and solid spheres
… applications. The mechanism of heat and mass transfer during the droplet solid collision is essential to the design and operation of many industrial systems. However, very limited systemic research is available to describe the droplet impact on hot solid spheres. This paper aims to establish a …
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An investigation of phase transfer catalysis employing quantitative structure-activity relationships
… quantitative structure activity relationships to phase transfer catalysis (PTC) has been explored. The primary focus was on hydroxide-initiated PTC reactions, such as enolate alkylations. The tandem [4+2]/[3+2] cycloaddition of nitroalkenes was applied as the key transformation in the preparation …
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Total Syntheses of (+)-Geldanamycin, (-)-Ragaglitazar, and (+)-Kurasoin A and Phase-Transfer-Catalyzed Asymmetric Alkylation
… glycolate alkylation has been developed using phase-transfer-catalysis (PTC). Diphenylmethoxy-2,5-dimethoxyacetophenone with trifluorobenzyl cinchonidinium catalyst and cesium hydroxide provided alkylation products at —35 °C in high yield (80-99%) and with excellent enantioselectivity (up to …
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Electrophilic C(sp²)–H Cyanation with Inorganic Cyanate (OCN⁻) by Pᴵᴵᴵ/Pⱽ=O-Catalyzed Phase Transfer Activation
… experiments show that under solid-liquid phase transfer, an inorganic cyanate is activated by halide displacement on a halophosphonium. Redox catalysis is enabled by the usage of a strained phosphine (phosphetane) so that catalyst turnover from phosphine oxide to phosphine can be easily …
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The chemistry of British bituminous coals : an assessment of phase transfer catalysed reactions in the determination of coal structure
… for study. Procedures were developed, using phase transfer catalysts (PTC's), to degrade the solvent insoluble fractions of the coals. PTC's are of interest because they have the potential to bring about selective high conversion reactions, under mild conditions, (often in the past, severe …
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Synthesis of Resveratrol and Its Analogs, Phase-Transfer Catalyzed Asymmetric Glycolate Aldol Reaction, and Total Synthesis of 8,9-Methylamido-Geldanamycin
… relative to resveratrol (24 μM). Cinchona phase-transfer catalysts (PTC) were developed for glycolate aldol reactions to give differentially protected 1,2-diol products. Silyl enol ether of diphenylmethoxy-2,5-dimethoxyacetophenone reacted to generate benzhydryl-protected products. O-Allyl …
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I. Catalyst development in asymmetric phase transfer catalysis employing QSAR methods II. Computational investigations on the stereochemical course of the addition of allylsilanes to aldehydes
Part I of this dissertation describes the investigation in APTC employing a chemoinformatic analysis of the alkylation of a protected glycine imine with libraries of enantiomerically enriched quaternary ammonium ions. The synthesis of the quaternary ammonium ions follows a diversity oriented …
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Synthesis of nitrogen-containing heterocycles using nitro compounds as building blocks: Part I: Synthesis of 3-substituted azepanes. Part II: Synthesis of 1-azoniapropellanes as phase transfer catalysts
… of chiral, enantiopure 1-azoniapropellanes as phase transfer catalysts has been developed. In the first method, the tandem [4+2]/[3+2] cycloaddition of nitroalkene was applied as the key step, wherein a chiral, enantiopure vinyl ether, a nitroalkene and a vinyl ketone were rapidly assembled. …
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Harnessing cheminformatics for catalyst design I. Investigation into a general, asymmetric synthesis of cinchona alkaloid analogs towards asymmetric phase transfer II. Development of an enantioselective brønsted acid catalyzed four-component Ugi reaction
… alkaloids were studied against an asymmetric phase transfer catalyzed cyclopropanation reaction. Second, (R)-BINOL derived phosphoric acids were studied in regards to the brønsted acid catalyzed Ugi reaction. In regards to Cinchona alkaloids, the concentration was first on methodology develop …
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Development of novel methodologies utilizing quaternary ammonium salts as catalysts
… this thesis (Chapter 3) details development of a phase transfer catalyzed [2,3]-sigmatropic rearrangement of allyloxy carbonyl compounds. Initial investigation focused on identifying viable substrate classes that would undergo selective [2,3]-rearrangement under phase transfer conditions. Under …
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Nanoemulsion-like Polymersomes for Nanoreactors
… ILs is limited by their high viscosity and cost. Phase transfer of IL-filled polymer vesicles (polymersomes) from the IL phase to water produces a very stable kind of "nanoemulsion"�. Nanoemulsion-like polymersomes have great potential as they confine a catalyst within the interiors, thus …
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Coordination Cages for the Separation and Transportation of Molecular Cargo
… soluble in only one of three immiscible liquid phases. In contrast to the static triphasic system described in the second chapter, the third chapter explores directed phase transfer of coordination cages and their cargos from water, across a phase interface, and into an ionic liquid phase. The …
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The Syntheses of Bis-Guanidium Salts and Their Applications in Asymmetric Mukaiyama Type SN2 Alkylation Reactions
… and successfully synthesized a new type of phase-transfer catalysts with full alkylated guanidiums as functional centers and applied these catalysts in asymmetric catalysis of 1,4-dicarbonyl compounds via Mukaiyama type SN2 alkylation reactions. Firstly, a series of bis-guanidium salts were …
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Desymmetrilizing Organic Molecules via Structural Functionalization
… the design and synthesis of new chiral phase-transfer-catalysts were performed. In these days, asymmetric catalyses have been among the most interesting and active research areas in organic and pharmaceutical sciences because chiral centers exist in numerous drugs and related materials. …
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