Thesis(B.Sc.)--University of Adelaide, dept. of Organic Chemistry, 1966. / Typescript.

This Dissertation investigates the kinetics of CO2 methanation over nickel and cobalt catalysts. Methanation was studied for both Ni/γ-Al2O3 and Co/ZrO2 catalysts, which were synthesised using an incipient wetness impregnation technique and subsequently characterised using analyses based on gas adsorption, XRD, TPR and thermogravimetry. Separately a CO hydrogenation reaction, the Fischer-Tropsch process, was modelled numerically to examine the influence of mass transfer in practical, commercial pellets of catalyst. The kinetics of methanation was investigated for Ni/γ-Al2O3 over a wide range of reactant partial pressures using a gradientless, spinning-basket reactor operated in batch mode and in a laboratory-scale, continuous fixed-bed reactor. Langmuir-Hinshelwood kinetic models were developed to represent the observed kinetics in each reactor: these models were then compared. For the batch reactor, a rate expression based the dissociation of a chemisorbed CO intermediate being the rate-limiting step was found to be consistent with the experimental results. However, results from the fixed-bed suggested that the hydrogenation of an adsorbed C atom determined the rate of reaction. These differences in the kinetics on Ni/γ-Al2O3 between the fixed-bed and batch reactors suggest that a Langmuir approach using a single, rate-determining step may not be representative across all conversions. The rate over the Co/ZrO2 catalyst was characterised in the fixed-bed reactor over a range of reactant partial pressures at temperatures between 433 K and 503 K. The rate was observed to be dependent on hydrogen partial pressure and temperature, with the rate increasing with both. Previous research has reported a wide range of values of the apparent activation energy, with a study suggesting it was sensitive to pressure. Accordingly, the apparent activation energy was investigated for pressure sensitivity over a range of pressures between 5 and 15 barg: it was found to be constant. The values determined (~88-91±8 kJ/mol) were notably consistent with those reported for CO hydrogenation on cobalt. Kinetic schemes based on Langmuir-Hinshelwood and power law equations were evaluated, with the results best described by a reaction scheme based on the carbide pathway, with a rate-determining step of CH hydrogenation. A reaction-diffusion model of the Fischer-Tropsch process in a 2-D hollow cylinder was developed and analysed across a range of Thiele moduli and the extents of error in both effectiveness factor and selectivity were quantified relative to one-dimensional sphere and slab analogues. The errors between 2-D and 1-D analogues were found to be most significant between Thiele moduli of ~0.25 and ~3. Hollow cylinder effectiveness factors were bounded by those of sphere and slab above and below Thiele moduli of ~0.75 and ~1.15 respectively for the conditions examined, with the effectiveness factors exceeding those of both sphere and slab models between these moduli. A comparison of the hollow cylindrical pellets against spheres of equivalent volume demonstrated that hollow cylinders provided improved fixed-bed performance, with improved effectiveness factors and selectivities due to the lowered diffusion lengths of the hollow cylindrical geometry.

Thesis advisor: James Morken / This dissertation will present two main projects focusing on the construction of enantiomerically enriched α-boryl organometallic reagents by transition metal catalysis. The first project describes the development of a platinum-catalyzed enantioselective hydrosilylation reaction of alkenyl boronic esters, which provides a general and efficient route to α-borylsilane species. Such species are configurationally stable and exhibit significant synthetic utilities. The second project depicts a nickel-catalyzed enantioselective carbozincation reaction of vinyl boronic esters, which for the first time giving approach to enantioenriched α-borylzinc reagents. These reagents possess good configurational stability at low temperatures and can participate in copper-catalyzed allylation, palladium-catalyzed Negishi cross-coupling and electrophilic halogenation reactions in stereospecific fashion to furnish a broad array of chiral boronic esters. These compounds are important and versatile building blocks in organic synthesis and utilized in the synthesis of (–)-aphanorphine and (–)-enterolactone. Detailed mechanistic studies were carried out, which revealed a nickel(I)-based redox neutral catalytic cycle. The properties of α-borylzinc compounds were also studied by 1H NMR and enabled the development of a stereoconvergent cross-coupling of racemic α-borylzinc reagents. Such catalytic system is also effective for an enantioselective silylzincation of vinyl boronic esters. / Thesis (PhD) — Boston College, 2021. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Thesis advisor: James P. Morken / Thesis advisor: Marc L. Snapper / This dissertation will present three projects focusing on the enantioselective synthesis and stereospecific transformation of alkylboronates. The first project describes the development of a nickel-catalyzed enantioselective dicarbofunctionalization of alkenylboronates, which provides a modular route to secondary alkylboronic esters. Intramolecular reaction leads to enantioselective synthesis of exocyclic boronates. The second project depicts a new method for the synthesis of azetidines, pyrrolidines and piperidines via an intramolecular amination of alkylboronic esters. Regioselective amination of vicinal bis(boronates) allows the synthesis of saturated azacycles bearing boronic ester substitutions that can serve as useful synthetic handles. As the transformation is stereospecific, stereodefined cyclic amines can be synthesized from the enantioenriched boronic esters. The method is applied to the synthesis of an intermediate towards a Kras G12C inhibitor. The third project describes the development of a new chiral auxiliary on boron that can be easily synthesized from inexpensive starting materials. The auxiliary is applied to a diastereoselective radical ring-opening/closing [3+2] cycloaddition of cyclopropylanilines with alkenylboron species. / Thesis (PhD) — Boston College, 2022. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

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This thesis focuses on the study of nickel boride as a catalyst in various coupling reactions. The nickel boride catalyst was investigated in three different coupling reactions, the experiments aimed at understanding the activity and catalytic properties of nickel boride. We successfully synthetized the nickel boride catalyst, alongside with the cobalt and iron boride. Different methods of preparation were compared and we concluded, that the differences in the preparation, such as solvent and atmosphere, influence the activity of the catalyst in coupling reactions. We found that the most suitable solvent for preparing nickel boride is anhydrous methanol, thus we proceeded our research with this catalyst. In the case of the Sonogashira cross-coupling we found that the homocoupling of the acetylene starting material is a side reaction we could not exclude. However, with the proper solvent it is possible to shift the reaction towards homocoupling, without the formation of the heterocoupling product. Thus, we decided to investigate the Glaser homocoupling between acetylenes. In the case of the Sonogashira coupling only TLC was used to examine the reaction mixture. However, in the case of Glaser coupling, after pre-investigations we developed a gas chromatography method for analyzing the reaction mixtures. We learned, that the homocoupling only results in trace amounts (2-4%) of product. Previous investigations in our research group showed, that the nickel boride could catalyze Suzuki-Miyaura-type couplings. Examining this reaction all three metal borides were tested; however, the reactions only led to the desired product with nickel boride. Analyzing the reaction with gas chromatography we learned that the choice of solvent influences the stability of the starting materials and the formation of side products. Reactions with different starting materials, in different solvents, with different bases were analyzed. The effect of microwave irradiation was also examined. Based on the results we concluded, that with nickel boride it is not possible to achieve high yields in coupling reactions.

The nucleophilic addition of organomagnesium/lithium reagents to aldehydes and ketones has long enabled the synthesis of valuable alcohol derivatives; however, these types of transformations are often plagued by poor functional group tolerance and require harsh reaction conditions. The direct coupling of carbonyls and alcohols with aryl halides is an appealing alternative to access secondary alcohol products. However, this necessitates a formal C-H bond activation which is not well established in the literature. Chapter 1 provides a detailed literature background of the transition metal-catalyzed functionalization of carbonyls and alcohols. The work discussed in Chapter 2 of this thesis demonstrates the addition of aryl halides to aryl and aliphatic aldehydes and alcohols providing secondary alcohol products in moderate to high yields. Key to the success of this transformation was the implementation of underexplored and readily synthesized 1,5-diaza-3,7-diphosphacyclooctane (P2N2) ligands. Chapter 3 extends the methodology established in chapter 2 and aims to get a preliminary understanding of the application and mechanism of the reaction described above. For this purpose, pharmaceutically relevant isatin substrates are derivatized, providing access to substitution at the 3-position. Coupling isatins with aryl halides yields 3-aryl-3-hydroxy-2-oxindole products which are scaffolds for many natural product derivatives. Through high-throughput experimentation (HTE), we were able to discover that 1,2-addition at the carbonyl position of isatins is highly compatible with our established system and led us to develop a modest scope as well as gain useful mechanistic insights for this coupling.

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