Part I. Diels-Alder cycloadditions of 1,2,3,4,9,9-hexachloro-1α,4α,4aα,8aβ-tetrahydro-l,4-methanonaphthalene (32) and 1,2,3,4,9,9-hexachloro-lα,4α,6,7- tetrahydro-l,4-methanonaphthalene (33) to 4-methyl- and 4-phenyl-l,2,4-triazoline-3,5-dione [MTAD and PTAD, respectively] and to N-methylmaleimide (NMM) have been studied. The structures of several of the resulting cycloadducts were determined by X-ray crystallographic methods. The observed stereoselectivity of each of these Diels-Alder reactions was further investigated via application of theoretical methods. Thus, semiempirical (AMI) and ab initio molecular orbital calculations were used to calculate relative energies. Ab initio calculations were employed to perform frontier molecular orbital analyses of diene-dienophile interactions.

<p>The C-O single bond is found in numerous functional motifs including carboxylic acids,</p> <p>alcohols, and ethers. These compounds represent ideal precursors towards C-X (X = C, H, or heteroatom) bond formation due to their inherent stability and abundance in nature. As such, synthetic chemists continue to develop new technologies for the transformation of these precursors into biologically useful targets such as amides and amines. However, due to the stability of the C-O single bond, accessing such targets remains a consistent challenge. The activation of the carboxylic acids towards peptide synthesis has been facilitated through various coupling agents, including organoboron and transition metal catalysts. However, coupling agents can generate stochiometric, difficult-to-remove, toxic waste by-products.</p> <p>Organoboron/transition metal catalyzed condensations offer a more atom economical approach but suffer from varying degrees of optical erosion and poor sustainability. Phosphonium-based deoxyaminative technologies provide access to amines from alcohols via a phosphorus oxygen double bond formation driving force, but possesses a narrow nucleophilic nitrogen source scope, and poor atom economy. Transition metal/enzyme catalyzed “hydrogen borrowings” represent atom economical deoxyaminative alternatives. Still, their respective use of costly metals, and multiple enzymatic cascade steps severely limit the sustainability and scope of such protocols.</p> <p>An ambient deoxyamidation of carboxylic acids and deoxyamination of alcohols was</p> <p>developed through the use of N-haloimides activated by triphenylphosphine. Such</p> <p>technologies were found to possess broad functional tolerance and formed C-N bonds via a</p> <p>coupling to free amines, and the direct installment of the imide motif. Mechanistic experiments suggest that such transformations take place via the in situ generation of two separate phosphonium reactive species. </p>

<p>In recent years, sulfonyl fluorides have garnered significant attention in the synthetic organic and biochemical communities. Sulfonyl fluorides exhibit unique reactivity, as nucleophilic addition to the sulfur atom and subsequent elimination of fluoride only occurs under specific reaction conditions (otherwise known as SuFEx). Due to their inherent stability, sulfonyl fluorides are commonly used as biochemical probes to elucidate the structure of proteins. Sulfonyl fluorides also hold promise as irreversible covalent inhibitors. Despite the many potential applications of sulfonyl fluorides, methods to access this functional group remain underdeveloped, often requiring complex starting materials, or the use of hazardous reagents.</p> <p>Electrochemistry offers an attractive alternative to standard preparations of sulfonyl fluorides. Chapter 1 provides an overview of modern methods employed to synthesize sulfonyl fluorides, as well as key developments in synthetic organic electrochemistry. Chapter 1 closes with how the standardization of electrochemical reactions has allowed synthetic organic chemists to accurately reproduce electrochemical transformations.</p> <p>In Chapter 2, we developed an electrochemical method to access sulfonyl fluorides. The developed method operates by subjecting sulfones to electrochemical conditions, which initiates fragmentation of C–S bonds, and subsequent fluorination of a radical intermediate to realize the sulfonyl fluoride functional group. Early optimization focused on the synthesis of an optimal leaving group to bias the system towards formation of the desired sulfonyl fluoride in the presence of AgF₂. Once a leaving group was established, Lewis acids were screened in an attempt to activate the sulfone for substitution. Lewis acidic additives were later determined to serve as sacrificial oxidants as they did not chelate the sulfone starting materials. Reactions were run in divided and undivided electrochemical cells depending on the fluorinating reagent. Reactions with AgF₂ were run in an undivided electrochemical cell to prevent cathodic plating of Ag⁰. However, comparable results were achieved in an undivided electrochemical cell if AgF₂ was replaced with Selectfluor. Investigation into the incorporation of the leaving group into other substrates is ongoing. We hope to further develop this methodology to access complex sulfonyl fluorides and encourage the development of electrochemical methods in synthetic organic chemistry.</p>

5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) was normally recognised as a Cl- channel inhibitor, but its specificity is in question, since an inhibitory effect against K⁺ channels has been reported. To identify the significance of the molecules structural components, NPPB and related compounds, such as 2-(3-phenylpropylamino) benzoic acid (PPAB), 5- nitro-2-heptylamino benzoic acid (HANB) and 2-nitro-5-heptylamino benzoic acid (HANB-2) were synthesised by reductive amination using various aldehydes and amines. Using internodal cells of the giant green Characean algae, Nitella hookeri, the effects of NPPB and related compounds on cytoplasmic streaming and turgor regulation were determined. Previous experiments stated that cytoplasmic streaming was sensitive to NPPB, PPAB and HANB with IC₅₀ values of 24µmol/L, 455µmol/L, and 6.4mmol/L, respectively. In this report, the IC₅₀ values of purchased NPPB and niflumic acid were found to be 88.65µmol/L and 121.82µmol/L, respectively. Although the IC₅₀ value of purchased NPPB showed a slight difference from that of synthesised NPPB, the results of the cytoplasmic streaming experiment indicated the possibility of this analysis to be a simple assay system for analysing the effects of structural modification to ion channel inhibitors on their biological activity. Moreover, NPPB and PPAB seem to stimulate regulation of turgor pressure under hyperosmotic shock, which can be explained by a blockage of K⁺ efflux during osmotic stress leading to faster recovery of turgor regulation. Additionally, the results of cytosolic free Ca²⁺ analysis using aequorin technology also suggested that the possibility of this analysis to be used as a more direct measure of the inhibitory effect, while the cytoplasmic streaming analysis is a more indirect method. The preliminary results from this research suggest the significance of the simple assay systems for analysing the effects of structural modification ion channel inhibitors, which can be used for future study regarding ion channel structures.

Nanomaterials (NMs) are materials in which the size of at least one dimension is less than 100 nm. Examples include quantum dots, nanoparticles, “Buckminsterfullerene (C60)”, carbon nanotubes, graphene and TiO2 thin films. Many research groups have investigated the properties of NMs, and they have reported that some of them are clearly different to those of the bulk materials, and depend on the size of the NMs. Examples include melting temperatures, phase transition pressures, fluorescence spectra, catalytic properties and magnetic properties. Recently, a high-pressure study of Te nano-cylinders revealed compressibility effects that are different to those observed in bulk-Te. Although this study reported an elevation of phase transition pressure compared to the bulk, the authors did not investigate the structures of the high-pressure phases, and it is unclear whether the incommensurate phase found at high pressures in bulk-Te was observed or not. Indeed, it is completely unknown whether the incommensurate phases observed in a number of elements at high pressure also exist in nanoparticle samples of the same materials. The search for, and study of, such phases forms the subject of this thesis. Initial studies of commercial selenium nanoparticles (nano-Se) revealed that the incommensurate phase of bulk selenium (Se-IV) is also found in nano-Se. The transition pressures in nano-Se are slightly higher than those of bulk-Se. However, the nano-Se samples were subsequently found not to have the sizes, shapes, and properties claimed by the vendor, which was confirmed by transmission and scanning electron microscopy. Further commercial samples of nano-Se and nano-Bi were also found to be of extremely poor quality. It was clear, therefore, that a detailed study of incommensurate phases in NMs would require us to make our own samples. Bismuth nanoparticles (nano-Bi) with dimensions 51(6), 52(15), 92(13), 128(45), and 138(27) nm have been successfully synthesised by the author in collaboration with the Hybrid Nano Collods group at the University of St. Andrews. On compression, the nano-Bi samples were found to have the same order of phases Bi-I, Bi-II, Bi-III, and Bi-V and phase transitions as found in bulk-Bi, but were found to exhibit larger phase coexistence. The phase transition pressures on pressure increase were higher than those of the bulk materials, and the smaller the diameter of nano-Bi, the higher the phase-transition pressure. This behaviour is similar to, but more extreme than, that found in CdSe nanoparticles. The incommensurate Bi-III structure has been found in nano-Bi under increases in pressure. However, the di↵raction patterns from Bi-III contain additional unaccounted-for peaks, and this phase is referred to as complex Bi-III. The Debye- Scherrer rings from complex Bi-III are smooth, and do not exhibit the spottiness observed in the diffraction patterns of Bi-III obtained from bulk-Bi. This enables full Rietveld refinement of Bi-III in the nano-samples. Complex Bi-III exists from 3 GPa up to 30 GPa, compared to the stable range of only 2.7 to 7.7 GPa of Bi-III in the bulk material. While such a large range of pressure enables the structure of nano-Bi-III to be studied over a much wider pressure range than bulk-Bi-III, such studies were hampered by the existence of the unaccounted-for peaks. In order to get clean, single-phase patterns of Bi-III, samples of this phase were first prepared on pressure decrease from the higher-pressure Bi-V phase, before recompressing them. Single-phase samples of Bi-III were obtained and were found to be stable up to 14-18 GPa. However, because of phase coexistence, diffraction peaks from Bi-III were still visible at pressures as high as ~30 GPa, which is ~3 times larger than the upper limit pressure of existence of bulk-Bi-III. On pressure re-increase, nano-Bi-III has a higher bulk modulus than bulk-Bi-III. The bulk modulus was found to be size-dependent as it is higher when size decreases. Moreover, nano-Bi has a smaller value of the incommensurate wave vector, which is almost pressure independent, but is found to be particles size dependent. The incommensurate wave vector thus becomes another of the structural and physical properties of nanomaterials that is found to be sample-size dependent.

These N-substituted piperidines, because of their similarity in structure to the pressor amines, are expected to be physiologically active. By varying the position and size of the alkyl groups attached to the pyridine ring, difference in degree and type of physiological activity are likely.

Magnetism lies at the core of modern technology and can be found in industries such as oil refining, automotive, telecommunications, personal electronics, and power generation that are integral to our day to day lives. This permeation into everyday life has been enhanced in the past several decades with improvements in material design based upon the principles of nanotechnology leading to smaller, faster, and more efficient devices. The presented research will discuss the synthesis and processing of multiple magnetic nanoparticle structures designed for the enhancement of various, application specific, properties. In the first experiments a tunable core/shell structure was developed with either enhanced optical properties or enhanced catalytic reactivity based solely upon small manipulations in the synthesis resulting in alternate morphologies. Essentially reaction times were controlled to direct core nucleation followed by shell growth and based upon addition times and concentration the final product could be manipulated as either a Fe/Ag or Ag/Fe core/shell. The modifications also resulted in Fe particles decorated with Ag islands that showed significant Plasmon shifts while still maintaining their high magnetization. These particles present applications in catalysts, sensors, and separations. Secondly FexCo100-x alloys were generated in order to determine the atomic compositions with the best magnetic properties. Several post-processing cleaning and annealing regimes were used to determine the most effective method of preparing the particles for utilization in devices. Annealing temperatures of 450°C were found most effective at enhancing magnetic properties while minimizing grain growth. Finally the synthesis of exchange-coupled hard magnetic core/shell nanoparticles was conducted. In this synthesis SmCo5 was synthesized via solvent assisted ball milling in oleic acid. Once completed these particles were processed in a multistep cleaning process which removed excess solvent and much of the surface oxidation. The particles were then suspended in a non-aqueous solvent and a magnetically coupled Co shell was carefully grown under sub-zero conditions. The resulting composite material demonstrated greatly enhanced magnetic properties and a unique laminated structure that had been elusive in nanoparticle research. Several magnetic nanoparticles and compositions were studied resulting in increased functionality based upon the bottom-up nanostructuring of materials. This work allows for the understanding of the effect of synthetic conditions on the control of nucleation and growth dynamics within nanoparticle synthesis and the generation of high quality functional magnetic materials.

Esta Tese apresenta duas revisões de literatura: 1. Síntese de aldeídos e cetonas a partir de compostos de enxofre. 2. Síntese de benzaldeídos deuterados. E descrita a reação de sulfenilação de benzil fenil sulfonas, conduzindo a um novo \"synthon\", &#945;-metiltio-benzil fenil sulfona (1). Y-C6H4-CH(SCH3)SO2C6H5 Y = H,CH3,Cl,OCH3,NO2,CN. É relatada a hidrólise ácida de (1), fornecendo benzaldeídos para substituídos. É proposta a decomposição térmica de (1), como um método novo de síntese de benzaldeídos para substituídos. É descrita uma reação de um passo só, envolvendo alquilação e decomposição térmica de (1) e fornecendo cetonas aromáticas. Este método permite sintetizar cetonas contendo grupos sensíveis a ácidos. O método pirolítico é aplicado à síntese de aldeídos aromáticos deuterados, que são obtidos em 98% de pureza isotópica. Os benzaldeídos deuterados e não deuterados são obtidos em bons rendimentos, não se notando diferenças provenientes do caráter eletrônico dos substituintes no anel. É apresentada uma discussão sobre os aspectos mecanísticos da decomposição térmica. / This thesis presents two literature reviews: 1. Synthesis of aldehydes and ketones, starting from the sulphur containing compounds 2. Synthesis of deuterated benzaldehydes. The sulphenylation reaction of benzyl phenyl sulphones, leading to a new \"synthon\", &#945;-methylthio-benzyl phenyl sulphone (1), is described. Y-C6H4-CH(SCH3)SO2C6H5 Y = H,CH3,OCH3,Cl,NO2,CN. Acid hydrolyses of (1) to give p-substituted benzaldehydes are reported. A novel reaction - Thermal Oecomposition of (1) - as an improved method for the synthesis of p-substituted benzaldehydes is proposed. One pot reaction, which consists of alkylation and thermal decomposition of (1), to give aromatic ketones, is reported. Some ketones containing acid-sensitive groups are obtained. The pyrolyt ic method is applied to the synthesis of deuterated aromatic aldehydes, which are obtained in 98% of isotopic purity. The yields of the deuterated and non-deuterated benzaldehydes are good, and do not show any dependence on the eletronic character of the para substituents. A discussion on some mechanistic aspects of the thermal decomposition is presented.

Óxidos e hidróxidos de alumínio vêm sendo alvo de estudos no Laboratório de Matérias-Primas Particuladas Prof. Pérsio de Souza Santos (LPSS) nas últimas seis décadas. Várias rotas de síntese de mono- e tri-hidróxidos foram pesquisadas, bem como as transformações térmicas desses materiais em aluminas de transição e alumina-alfa. Mais recentemente, a síntese de boemita a partir do tratamento hidrotérmico de gibsita vem sendo o principal objeto dos estudos realizados no LPSS. Nesta Tese, a síntese hidrotérmica de boemita a partir de uma gibsita Bayer comercial foi estudada. Os cristais produzidos foram caracterizados por difração de raios X (DRX), por análises térmicas (TGA e DTA) e por microscopia eletrônica de varredura (MEV). Diferentes morfologias de cristais de boemita foram obtidas - cristais com dimensionalidade \"3D\" (cubos e paralelepípedos), \"2D\" (placas espessas, placas finas e placas alongadas) e \"1D\" (placas alongadas e ripas) por meio da variação da composição do meio reacional inicial. Reações conduzidas em meios com pH característico de suspensões de gibsita em água (pH alcalino) resultaram em cristais com morfologia \"3D\" ou \"2D espessa\", enquanto reações conduzidas em meio acidificado (pH = 2,0) resultaram em cristais com morfologia \"2D\". Reações conduzidas em meios acidificados contendo íon acetato levaram a cristais com morfologia \"2D fina e alongada\" ou morfologia \"1D\", dependendo da relação molar [Al : acetato] inicial de íon acetato (morfologia \"1D\" necessita de uma relação molar de no mínimo 1mol Al : 1mol acetato). Os cristais com morfologia \"1D\" e \"2D fina\" apresentaram espessuras nanométricas. A evolução térmica dos cristais de boemita produzidos foi estudada após aquecimentos entre 200ºC e 1200ºC. Todas as boemitas seguiram as transformações térmicas da chamada \"série ?\" , independentemente da sua morfologia, ou seja: boemita -> alumina-? -> alumina-? / alumina-? -> alumina-?. A temperatura de transformação da boemita em alumina-? é afetada pela morfologia dos cristais, ocorrendo em temperaturas mais baixas nos materiais com cristais de espessura nanométrica (morfologias \"1D\" e \"2D fina\"). Alumina-? com diferentes morfologias e diferentes áreas específicas (determinadas pelo método BET aplicado a isotermas de adsorção de nitrogênio gasoso a 77K) foram obtidas: 136 m2/g para alumina-? \"1D\"; 73,4 m2/g para alumina-? \"2D fina e alongada\"; 40,3 m2/g para alumina-? \"3D\". Foi possível, portanto, obter aluminas de transição potencialmente interessantes para aplicações industriais dadas as elevadas áreas específicas observadas. / Aluminum oxides and hydroxides have been the subject of studies in Laboratório de Matérias-Primas Particuladas Prof. Pérsio de Souza Santos (LPSS) in the last six decades. Several synthesis routes for mono- and tri-hydroxides were investigated as well as the thermal processing of these materials into transition aluminas and alpha-alumina. More recently, the synthesis of boehmite from the hydrothermal treatment of gibbsite has been the main object of studies in LPSS. In this Thesis, the hydrothermal synthesis of boehmite from a commercial Bayer gibbsite was studied. The crystals produced were characterized by X-ray diffraction (XRD), thermal analysis (TGA and DTA) and scanning electron microscopy (SEM). Different boehmite crystal morphologies were obtained - crystals \"3D\" (cubes and parallelepipeds), \"2D\" (thick plates, thin and elongated plates) and \"1D\" (elongated plates and strips) by varying the composition the initial reaction medium. Reactions conducted in media with characteristic pH of gibbsite suspension in water (alkaline pH) resulted in crystals with morphologies \"3D\" or \"thick 2D\" while reactions carried out in acidic medium (pH = 2.0) resulted in crystals with morphology \"2D\". Reactions carried out in acidic media containing acetate ion led to crystals with a \"thin and elongated 2D\" morphology or \"1D\" morphology, depending on the pristine [Al: acetate]. molar ratio (\"1D\" morphology requires a pristine molar ratio of at least 1mol Al: 1mol acetate). Crystals with \"1D\" or \"2D thin\" morphologies presented nanometric thickness. The thermal evolution of boehmite crystals produced was studied after heating between 200oC and 1200oC. All boehmites following thermal \"?-series\" transformation, regardless of their morphology, that is: boehmite -> ?-alumina -> ?-alumina /?-alumina -> ?-alumina. The transformation temperature of boehmite into ?-alumina is affected by crystal morphology, occurring at lower temperatures in the materials with nanometer thick crystals (\"1D\" and \"2D thin\" morphologies). ?-alumina with different morphologies and different specific surface areas (determined by BET method applied to adsorption isotherms of gaseous nitrogen at 77K) were obtained: 136 m2/g for ?-alumina \"1D\"; 73.4 m2/g for ?-alumina \"thin and elongated 2D\"; 40.3 m2/g for ?-alumina \"3D\". It was therefore possible to obtain transition aluminas potentially interesting for industrial applications given the high specific surface areas observed.

Lee Hing Ken. / "November 2001." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 154-159). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.