Total synthesis of the pyrrolizidine alkaloid NP25302: (+)-NP25302 is an unusual vinylogous urea containing pyrrolizidine alkaloid shown to exhibit cell adhesion inhibition. It was envisaged that this natural product could be accessed by a novel 5-endo-dig cyclisation to construct the pyrrolizidine core, and a Curtius rearrangement to install the vinylogous urea motif. This methodology was first tested on a model system, furnishing nor-NP25302 from L-proline in 12 steps and 9% overall yield. The total synthesis of (±)-NP25302 was completed in 9 steps and 26% overall yield from ethyl 2-nitropropionate using similar methodology. Studies into the stereospecificity of the Au(I)-catalysed cyclisation of monoallylic diols: During the synthesis of (+)-isoaltholactone in the Robertson group, the key Au(I)-catalysed cyclisation was observed to occur with some stereospecificity. Further investigations were therefore conducted into the stereochemical outcome of this reaction using stereodefined allylic alcohols, and from the combined results a mnemonic was proposed to predict the stereochemistry of the products of this reaction. Studies into the total synthesis of ascospiroketals A and B: Investigations were conducted into the total synthesis of the recently isolated natural products ascospiroketals A and B. A second generation synthesis was used to construct advanced intermediates 1 and 2.

<p>This thesis describes how radical cyclization chemistry can be applied for the construction of heterocyclic compounds.</p><p>In the first part, a series of electron deficient α-phenylselenenylalkenes were prepared <i>via</i> a PhSeCl-addition/HCl-elimination sequence. Allyl- and propargylamines readily underwent conjugate addition to these species to produce pyrrolidines or dihydropyrrol derivatives, after triethylborane initiated reductive radical cyclization in the presence of tris(trimethylsilyl)silane.</p><p>The second part describes a convergent synthesis of the pineal hormone melatonin. The indole nucleus is secured <i>via</i> a tris(trimethylsilyl)silane mediated<i> 5-exo</i> radical cyclization. The protocol provides convenient and simple access to compounds useful for studies of biological activity and structure activity relationships.</p><p>The third part describes construction of substituted tetrahydrofuran-3-ones and pyrrolidin-3-ones. Regioselective ring-opening of epoxides or aziridines with benzeneselenolate/tellurolate, followed by Michael addition to electron deficient alkynes afforded the corresponding O/N-vinylated compounds. The tetrahydrofuran-3-ones and pyrrolidin-3-ones were secured <i>via </i>radical carbonylation/reductive cyclization using pressurized carbon monoxide (80 atm).</p><p>The fourth part is concerned with the effect of an N-protecting group on the cyclization of 2-substituted-3-aza-5-hexenyl radicals. Relative energies for reactants and transition states were determined using density functional calculations. Reactant and transition state conformers leading to <i>cis</i>-product were lower in energy than those leading to<i> trans</i>-product. The results can be explained by the unfavorable 1,2-strain present in chair-equatorial and boat-equatorial conformers.</p>

This thesis describes how radical cyclization chemistry can be applied for the construction of heterocyclic compounds. In the first part, a series of electron deficient α-phenylselenenylalkenes were prepared via a PhSeCl-addition/HCl-elimination sequence. Allyl- and propargylamines readily underwent conjugate addition to these species to produce pyrrolidines or dihydropyrrol derivatives, after triethylborane initiated reductive radical cyclization in the presence of tris(trimethylsilyl)silane. The second part describes a convergent synthesis of the pineal hormone melatonin. The indole nucleus is secured via a tris(trimethylsilyl)silane mediated 5-exo radical cyclization. The protocol provides convenient and simple access to compounds useful for studies of biological activity and structure activity relationships. The third part describes construction of substituted tetrahydrofuran-3-ones and pyrrolidin-3-ones. Regioselective ring-opening of epoxides or aziridines with benzeneselenolate/tellurolate, followed by Michael addition to electron deficient alkynes afforded the corresponding O/N-vinylated compounds. The tetrahydrofuran-3-ones and pyrrolidin-3-ones were secured via radical carbonylation/reductive cyclization using pressurized carbon monoxide (80 atm). The fourth part is concerned with the effect of an N-protecting group on the cyclization of 2-substituted-3-aza-5-hexenyl radicals. Relative energies for reactants and transition states were determined using density functional calculations. Reactant and transition state conformers leading to cis-product were lower in energy than those leading to trans-product. The results can be explained by the unfavorable 1,2-strain present in chair-equatorial and boat-equatorial conformers.

The thermal properties of hydrate bearing sediments remain poorly studied, in part due to measurement difficulties inside the hydrate stability envelope. In particular, there is a dearth of experimental data on hydrate-bearing sediments, and most available measurements and models correspond to bulk gas hydrates. However, hydrates in nature largely occur in porous media, e.g. sand, silt and clay. The purpose of this research is to determine the thermal properties of hydrate-bearing sediments under laboratory conditions, for a wide range of soils from coarse-grained sand to fine-grained silica flour and kaolinite. The thermal conductivity is measured before and after hydrate formation, at effective confining stress in the range from 0.03 MPa to 1 MPa. Results show the complex interplay between soil grain size, effective confinement and the amount of the pore space filled with hydrate on the thermal conductivity of hydrate-bearing sediments.

Gas hydrate formation generally involves gas dissolution, formation of nuclei and growth of new nucleus. On condition of synthesizing experiments without agitation, the formation of hydrate nuclei is comparatively difficult and needs an induction period which is considerably uncertain and random. Some additives such as surfactant sodium dodecyl sulfate (SDS) can increase the formation rate and reduce the induction time. A hydrate formation and mini drilling experimental system was used to carry on methane hydrate formation experiments with small quantity of SDS and SDS- tetrahydrofuran(THF) in deionized water. The reactor is a high pressure cell (40Mpa) made of titanium alloy with 4 transparent windows and an inner volume of about 2.8 liters. The effect of SDS and THF hydrate on the formation rate and amount of methane hydrate was studied by comparative testing and analyzing the collected data of temperature and pressure. According to the results of the tests, the formation rate of methane hydrate in the SDS-THF solution was faster than that in the SDS solution. As a water-soluble hydrate former, THF hydrate nucleation may be benefit of methane hydrate nucleation. A small amount of SDS and THF could dramatically promote the formation of methane hydrate in the pure water, and rapidly increase the amount of methane hydrate too. Therefore, a great deal of time for experiment was saved, which established a good basis for the coming mini drilling and drilling fluid experiments.

Certain organisms, including some bugs (both insects and microbes) are able to survive low temperatures by the production of either ice nucleating proteins (INPs) or antifreeze proteins (AFPs). INPs direct crystal growth by inducing rapid ice formation whereas AFPs adsorb to ice embryos and decrease the temperature at which the ice grows. We have also shown that certain AFPs can inhibit the crystallization of clathrate hydrates and eliminate more rapid recrystallization or “memory effect”. Here we examine several bacterial species with iceassociating properties for their effect on tetrahydrofuran (THF) hydrate crystallization. The bacteria Chryseobacterium sp. C14, which shares the ice recrystallization inhibition ability of AFPs, increased induction time to THF hydrate crystallization in isothermal experiments. In an effort to understand the association between AFPs and THF hydrate we have produced bacterially-expressed AFPs as probes for hydrate binding. Although the structure of hydrates is clearly distinct from ice, the apparent potential for these products to perturb clathrate hydrate growth compels us to explore new techniques to uncover “green inhibitors” for hydrate binding.

Cyclopentane hydrate interparticle adhesion force measurements were performed in pure cyclopentane liquid using a micromechanical force apparatus. Cyclopentane hydrate adhesion force measurements were compared to those of cyclic ethers, tetrahydrofuran and ethylene oxide, which were suspected to be cyclic ether-lean and thus contain a second ice phase. This additional ice phase led to an over-prediction of the hydrate interparticle forces by the capillary bridge theory. The adhesion forces obtained for cyclopentane hydrate at atmospheric pressure over a temperature range from 274-279 K were lower than those obtained for the cyclic ethers at similar subcoolings from the formation temperature of the hydrate. The measured cyclopentane interparticle adhesion forces increased linearly with increasing temperature, and are on the same order of magnitude as those predicted by the Camargo and Palermo rheology model.

Capacitance manometer with sensors maintained at temperatures above the temperature of the vacuum vessel may read a higher gas pressure than the true value. This arises due to a transport process of molecules induced by molecule-surface collisions called thermal transpiration effect. Thermal transpiration effect depends on the pressure, the temperature gradient, gas, geometry and surface properties of the interconnecting pipe between the capacitance manometer and the vacuum vessel. To determine the height of the thermal transpiration effect for the biomolecular gas tetrahydrofuran, an experimental setup has been built. Its suitability to measure the thermal transpiration effect has been tested. Measurements of thermal transpiration effects for nitrogen and tetrahydrofuran have been analyzed with the semi-empirical Takaishi-Sensui equation. The coefficients of the Takaishi-Sensui equation can be used to determine the magnitude of the thermal transpiration effect for different temperature gradients, diameters of the interconnecting pipe and pressures.

The replacement or loading-reduction of precious metal catalysts with low-cost, earth-abundant materials is an important step for the development of next-generation industrial chemical processes. By decreasing the potential cost of an electrolyzer device or enabling new pathways of upgrading biomass-derived oxygenates (BDOs), the nitrides and oxides of earth-abundant transition metals may be strategically utilized for the modular use of renewable power or the transition of conventional chemical feedstocks to renewable sources. This thesis uses a combination of electrochemical and surface science techniques to study the catalytic properties of nitrogen- and oxygen-modified earth-abundant materials for the electrolysis of water, and the surface reactions of three BDOs: ethanol, glycerol, and tetrahydrofurfuryl alcohol (THFA). The development of stable, active, and low-cost electrocatalysts with reduced platinum group metal (PGM) loading for the hydrogen evolution reaction (HER) is an important step towards the grid-level implementation of electrolyzers. In this thesis, the electrochemical stability of tungsten nitride (WN) and niobium nitride (NbN) was characterized over broad pH-potential regimes, from which pseudo-Pourbaix diagrams were developed. In addition, unmodified and platinum-modified WN and NbN thin films were assessed for HER, where monolayer (ML) Pt-modification led to Pt-like HER activity in acid electrolyte. The selective bond scission of oxygen-rich and functionally complex biomass-derived oxygenates offers a unique opportunity to convert renewable biomass, as opposed to fossil fuels, into important industrial feedstocks. The fundamental surface reactions of three BDOs, either lignin-derived or biofuel-derived, was studied in this thesis. Ethanol reforming was studied on unmodified and Pt-modified Mo2N thin film surfaces for the production of synthesis gas, or syngas, a CO and H₂ gas feedstock for Fischer-Tropsch synthesis. Mo₂N, and the Mo₂C carbide analogue, have exhibited strong oxophilicity for the reaction of simple and complex alcohols that results in unselective C-O bond scission. Pt-modification was used to selectively conserve the C-O bond for CO production, and cleave the C-H and C-C bonds for H2 generation. Pt-modification shifted the reaction pathway from undesired decomposition on Mo₂N to reforming, while inhibiting undesired pathways such as ethylene or methane production. The hydrodeoxygenation (HDO) of glycerol, the primary manufacturing byproduct of biodiesel, to propylene was studied on WOx-modified Pt(111) surfaces. Two WOx active sites were observed for the deoxygenation of glycerol: Brønsted acid WOx sites for dehydration and oxygen vacancy sites for hydrodeoxygenation (HDO). While the undesired dehydration of glycerol to acrolein was most active on surfaces with thick WOx coverages, propylene production via the HDO pathway was more facile at intermediate coverages. Lastly, the ring-opening of THFA, a promising biomass-derived platform oxygenate, was studied on WOx/Pt(111) surfaces. The desired ring-opened product, 1,5-PeD, was also used as a probe molecule to study binding and desorption on WOx/Pt(111) surfaces. This work indicates that WOx-modification weakens the interaction between the ring-opened intermediate and the surface, to an extent that facilitates the hydrogenation of the 1,5-PeD-like intermediate and the desorption of gas-phase 1,5-PeD.

<p>U ovom radu kori&scaron;cen je spektroskopski, teorijski i hemometrijski pristup<br />proucavanju N-HO i N-H&middot;&middot;&middot; vodonicne veze koja se uspostavlja izmedu<br />amidnog protona i etarskog kiseonika tj aromaticnog sistema. U ovom radu<br />odredeni su parametri N-HO i N-H vodonicne veze za &scaron;esnaest Nsupstituisanih<br />amida sa tetrahidrofuranom i toluenom. Vecina ispitivanih amida do<br />sada nije bila izucavana sa stanovi&scaron;ta vodonicne veze. Uspostavljene su korelacije<br />izmedu spektorsopskih i teorijskih parametara. Izvr&scaron;eno je poredenje medu<br />osobinama vodonicno vezanih kompleksa za razlicite amide kao proton donore.<br />Svih 32 ispitivanih vodonicno vezanih kompleksa okarakterisano je<br />hemometrijskim metodama: Klaster analizom i analizom glavne komponente, na<br />osnovu spektroskopskih, teorijskih i Taftovih parametara</p> / <p> In this PhD thesis, N-H&times;&times;&times;O and N-H&middot;&middot;&middot; hydrogen bond beetwen the amide<br /> proton with ether oxygen and aromatic system has been investigated using the<br /> spectroscopic and theoretical approach. The study included sixteen N-substituted<br /> amides (formamides, acetamides, caproamides and benzamides) as well as<br /> tetrahydrofuran and toluene. The possibility of using chemometric methods was<br /> investigated in order to characterise N-H...O and N-H&middot;&middot;&middot; hydrgen bonded<br /> complexes. Hierarchial clustering and Principal Component Analysis (PCA) have<br /> been applied on infrared spectroscopic, PM3 theoretical and Taft parameters of 32 Nsubstituted<br /> amide complexes with tetrahydrofuran and toluene</p>