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HYDROGEN BOND CATALYZED EPOXIDATION AND DIHYDROXYLATION OF UNACTIVATED ALKENES
Title
HYDROGEN BOND CATALYZED EPOXIDATION AND DIHYDROXYLATION OF UNACTIVATED ALKENES
Creator
Kang, Lili
Date
2011-12, 2011-12
Description
Asymmetric epoxidation and dihydroxylation have been studied over decades using transition metals and chiral ligands. This research focused on...
Show moreAsymmetric epoxidation and dihydroxylation have been studied over decades using transition metals and chiral ligands. This research focused on metal free, hydrogen-bonding activation of the oxidant, such as hydrogen peroxide. In order to activate hydrogen peroxide, different types of catalysts, including BINOLs, calixarenes and carboxylic acids were synthesized, characterized and tested. The activity tests showed that carboxylic acids were able to activate hydrogen peroxide and alkyl hydroperoxides to give epoxides and diols as products. Various carboxylic acids, such as commercial available achiral and chiral carboxylic acids, dicarboxylic acids, as well as synthesized trans- and cis-dicarboxylic acid, were tested with different substrates to maximize the yield and enantioselectivity. A current reaction system uses 10 mol % catalyst, no solvent and provides the epoxide with 70% yield and 60% ee over 24 hours.
M.S. in Chemisty, December 2011
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SYNTHESIS AND POST-SYNTHETIC MODIFICATION OF TETRAZINE-BASED ORGANIC FRAMEWORKS
Title
SYNTHESIS AND POST-SYNTHETIC MODIFICATION OF TETRAZINE-BASED ORGANIC FRAMEWORKS
Creator
Kang, Lili
Date
2016, 2016-05
Description
Porous organic polymers (POPs) have been studied extensively over the past decade. The intrinsic porosity and tunable chemical structures have...
Show morePorous organic polymers (POPs) have been studied extensively over the past decade. The intrinsic porosity and tunable chemical structures have seen applications in gas storage, separations, and even catalysis. However, a vast majority of the POPs rely on a narrow class of monomeric units and polymerization conditions which limit the diversity of functionality in the polymers, and hence their chemical properties. To get around these issues, a micro- and mesoporous tetrazine-based organic framework with BET surface area of 170 m2/g was synthesized through palladium catalyzed cross-coupling reaction. The structure of the polymer was confirmed by solid-state 13C NMR, ATR-IR, and EDX. The 1,2,4,5-tetrazine units on the struts of the framework were active toward inverse electron-demand Diels-Alder reactions, allowing for a post-synthetic introduction of different functionalities into the tetrazinebased organic frameworks (TzOF). The structures of modified polymers were verifed by solid-state 13C NMR and ATR-IR. To eliminate the use of transition metals during synthesis, a new class of sulfur-containing tetrazine-based organic framework was designed and synthesized by nucleophilic aromatic substitution reactions. The resulting mesoporous polymer framework, with 3,6-dithio-1,2,4,5-tetrazine unit on the struts, showed BET surface are of 38 m2/g. The structure of the framework was confirmed by ATR-IR and EDX. Post-synthetic modifications of the polymer were also achieved by reacting with dienophiles through inverse electron-demand Diels-Alder reactions. The structures of modified polymers were verified by ATR-IR. These two synthetic methods we have developed for tetrazine-based organic frameworks and their ability to introduce functionality post-synthetically brought additional functionalities to the POP family.
Ph.D. in Chemistry, May 2016
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