Dissertations / Theses on the topic 'Organosulfur'
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Haughey, Simon Anthony. "Chemoenzymatic synthesis of organosulfur compounds." Thesis, Queen's University Belfast, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318731.
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King, Alistair William Thomas. "Chemoenzymatic synthesis of chiral organosulfur compounds." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396118.
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Chowdhury, Mohima Begum Roomi. "Unsaturated organosulfur chemistry : synthesis and applications." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10045805/.
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The original focus of this thesis was ynol ether synthesis which was successful using simple and easy-to-prepare precursors (chloroacetylenes) but low yielding. Attention was then diverted to the design and synthesis of a range of thioynol ethers (alkynyl sulfides) utilising chloroacetylenes. The reaction of a chloroacetylene with a thiolate salt in the presence of an amine mediator (Me2NH or DMEDA) yielded the alkynyl sulfides in excellent yields. The alkynyl chlorides were easily prepared from the parent alkynes contrasting sharply with the cumbersome synthesis of an alkynyl sulfonamide previously required. As well as chloroacetylenes, bromo- and iodoacetylenes have also been studied and the differences in their reactivity are highlighted. With a successful route to thioynol ethers at hand, brief mechanistic investigations were conducted into their reactivity. Finally, preliminary studies have been carried out on the reactivity of their derivatives.
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Class, Caleb Andrew. "Predicting organosulfur chemistry in fuel sources." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98155.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references.
Desulfurization of fossil fuels with supercritical water (SCW) has been the topic of many studies over the past few decades. This process does not require the use of any catalyst, eliminates the need for a hydrogen feed, and minimizes coke formation. Previous research has shown that it has the potential to be a viable commercial process, and recent experimental studies have proven that water acts as one hydrogen source for sulfur removal in this process. However, the exact desulfurization mechanism is largely unknown, as are many other reaction mechanisms involving sulfur compounds. Recent work has greatly expanded our ability to build comprehensive reaction mechanisms automatically for the decomposition of organic sulfur compounds using the automated Reaction Mechanism Generator (RMG). This thesis presents the implementation of this and other tools to investigate chemical processes relevant to our use of fuel sources containing sulfur compounds, and it shows some steps that have been taken to improve our predictions for these mechanisms and those that will be generated in the future. Previous investigations had focused on the pyrolysis of small sulfur compounds containing less than six heavy atoms, so RMG is first used to study the pyrolysis of t-butyl sulfide. A detailed reaction mechanism is then presented for the SCW desulfurization of hexyl sulfide. Comprehensive kinetic mechanisms for these larger molecules are likely to include thousands of reactions, so RMG builds this model in a systematic and unbiased way using a database of ab initio data. This database is expanded with potentially relevant thermochemical and kinetic parameters using transition state theory and quantum chemical calculations at the CBS-QB3 and CCSD(T)-F12 levels of theory. With these data, as well as previously calculated rates for hydrocarbon and sulfur kinetics, RMG is used to build a reaction mechanism for the conversion of hexyl sulfide to hydrogen sulfide, pentane, and carbon monoxide in the presence of SCW. This mechanism is validated with results from batch and flow reactor experiments, and predictions are accurate within a factor of two for reactant and major product concentrations. Analysis of the proposed mechanism shows that the molecular addition of water to the carbonsulfur double-bond in hexanethial is a key step in the SCW process, as this not only leads to the desulfurization of the compound, but also prevents the thioaldehyde from undergoing addition reactions with other hydrocarbons in a process that could eventually form coke. Thus, this work not only has implications in the SCW desulfurization process, but in the overall crude oil upgrading process as well. The calculated kinetic and thermochemical parameters are used to generate predictive reaction mechanisms for other processes relevant in fuel chemistry, such as the geological formation of oil and gas from kerogen. This not only allows us to model experimental work investigating the effect sulfur compounds have on the oil-to-gas process, but we also explore how these effects differ at geological conditions and timescales. And as the possible applications of RMG grow, the need for accurate parameters in mechanism generation become even more critical. A thermochemical database is generated for a wide variety of sulfur compounds using the highaccuracy CCSD(T)-F12/cc-pVTZ-F12 method, and this provides a basis for the investigation of organosulfur chemistry with tighter uncertainty.
by Caleb Andrew Class.
Ph. D.
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Ramesha, A. R. "Organosulfur Reactions In Organic Synthesis With Tetrathiomolybdate." Thesis, Indian Institute of Science, 1994. http://hdl.handle.net/2005/107.
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Recent years have seen a dramatic expansion in synthetic and structural molybdenum - sulfur chemistry. The amplest binary Mo-S moiety in MO$ ion. The thromolybdates derived by sulfur substitution from the 0x0 analogue have interesting chemical properties. Although they have been studied extensively by synthetic inorganic chemists and bio-inorganic chemists as models for enzymes like introgenases, their reactivity towards organic substrates remamed unexplored.
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Shepherd, S. D. "Chemical and enzymatic synthesis of organosulfur compounds." Thesis, Anglia Ruskin University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396225.
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Hendrickx, Ramon Adriaan Antonius Johannes Hendrickx. "Mechanistic studies of organosulfur oxidations by dimethyldioxirane." Thesis, University of York, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399615.
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Murray, Jane. "Selective oxidation of organosulfur substrates by hydrogen peroxide." Thesis, University of York, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428461.
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Savoie, Paul R. "Preparation, chemistry, and characterization of hypervalent organosulfur fluorides." Thesis, State University of New York at Albany, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3739734.
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Since the discovery of the pentafluorosulfanyl (SF5) group around the 1960s, progress in exploring the chemistry of aliphatic SF 5-containing compounds stagnated because of a lack of efficient synthetic methods. More recent developments in the preparations of SF5-containing compounds afforded easier access to these compounds, and sparked great interest in exploring their chemistry. Chapter 1 discusses the development of efficient methods used to prepare SF5-containing aliphatic compounds.
This dissertation investigates the combination of steric and polar effects of pentafluorosulfanylation on aliphatic molecules. Chapter 2 discusses the synthesis and chemistry of aliphatic aldehydes and aldimines containing the SF5 group in the 2-position. The aldehydes undergo many of the common chemical transformations of aliphatic aldehydes, affording a variety of SF5-containing compounds. The large C–S bond dipole helps direct additions to the carbonyl group in a manner consistent with the Cornforth hypothesis, resulting in highly diastereoselective nucleophilic additions. Similarly, the synthesis of SF5-containing SF5β-lactams by [2+2] cycloadditions of 2-pentafluorosulfanylaldimines with azidoketene proceeds with high diastereofacial selectivity. The SF5 β-lactams formed by this reaction may lead to a greater variety of diastereoselectively-prepared amino acid compounds for study in peptides, the preparation of new antibacterial compounds, and the design of novel SF5 β-lactamase inhibitors.
Chapter 3 discusses the structural studies of some synthesized pentafluorosulfanylated molecules to help further elucidate the steric and polar effects of pentafluorosulfanylation on aliphatic compounds. Coupling constant analyses determined the local molecular structure near the SF5 group and revealed that the unexpected diastereotopic resonances in 1H NMR spectra were the result of partial insertion of a hydrogen atom between two equatorial fluorine atoms, thus “locking” the conformation of the alkyl chain near the SF5 group. Computational experiments confirmed the experimentally-determined S–C–C–O dihedral angle of 85° observed in the alcohols formed by nucleophilic addition to the aldehyde carbonyl group of 2-pentafluorosulfanyl aldehydes. Computation of the reaction profile for the [2+2] cycloaddition of 2-pentafluorosulfanylaldimines with azidoketene revealed a difference in the reaction barriers leading to the two diastereomeric pairs of products of about 4.1 kcal/mol. Formation of the 1,2-lk,lk products is favored over the formation of the other possible products.
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Brooks, Andrew C. "The preparation of organosulfur derived electron transfer salts." Thesis, Nottingham Trent University, 2009. http://irep.ntu.ac.uk/id/eprint/284/.
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The concept of this thesis is to effect greater control over the crystalline state of radical cation salts in order to enhance electron transport, and to allow for the incorporation of additional functionality such as optical activity or magnetism. The salts formed are based on the bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) framework, and are produced using the technique of electrocrystallisation. In attempts to control the crystal packing arrangements observed, a number of approaches have been explored including the incorporation of chirality, hydrogen bonding interactions and coordinate bonding interactions. These properties have been installed on the electron donor molecule and/ or the charge stabilising anion component. This thesis presents a novel radical cation salt that has been prepared from ET and the sulfamate anion, and which exhibits ordered channels of hydrogen bonded anions and water molecules extending in one crystallographic dimension. This research has also discovered an unusual chiral crystallographic packing observed in a novel semiconducting radical cation salt formed from ET and the bromide anion. Also presented are the synthesis of a family of metal-binding electron donors and the first radical cation salts formed from these, including a perrhenate salt which is both N-protonated and oxidised, giving an overall charge of +2 on the electron donor molecule. A group of novel aldehyde-functionalised donors are discussed, one of which could lead to a Little-type superconductor, and the syntheses towards a bis(donor) molecule containing a spiro centre, and separately a porphyrin appended electron donor are presented.
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Takada, Hiroya. "Novel Asymmetric Reactions of Organosulfur and Organoselenium Compounds." Kyoto University, 1999. http://hdl.handle.net/2433/181822.
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Serapian, Stefano. "Simulating self-assembly of organosulfur species on gold nanoparticles." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/24839.
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This Thesis aims to establish an accurate but computationally effective method for simulating self-assembly of organosulfurs on gold nanoparticles (AuNPs), a process resulting in their functionalisation. A second gold rush is currently rekindling chemists' interest in the synthesis of novel functionalised AuNPs: these can bear the most chemically diverse functional groups, making them employable in a wide variety of applications, from optoelectronics to catalysis. Some aspects of self-assembly remain experimentally unclear at the mechanistic and electronic levels: achieving its accurate reproduction in silico would indeed represent an important contribution in the synthesis of functionalised AuNPs. This task, however, has so far proven difficult to achieve. In this work, I set out and review four fundamental challenges facing the computational chemist aiming to simulate self-assembly, and describe the strategy chosen to overcome them, using thiols (RSH) as the reference organosulfur. These challenges involve proper reproduction of: I) gold's relativistic effects and aurophilicity; II) the extensive surface reconstruction occurring upon self-assembly, with formation of RS-Au-SR staples and hydrogen loss; III) the large scale ligands involved in the process and their interactions; and IV) the fluctuating solvent environment in which it occurs. Confined to the AuNP core and RSH headgroups, challenges I and II involve complex electronic properties and entail electronic change, with bonds being cleaved (S-H) and reformed (S-Au, possibly H-H): overcoming them requires explicit simulation of electrons with a QM method (DFT). Challenges III and IV involve the entire RSH-AuNP system, including RSH tails of typically ~10^2 atoms: QM methods become impracticable at these system sizes, and a less costly classical forcefield treatment (MM) is necessary in this case, at least in part. The work presented here then proceeds towards the stated aim by attempting to resolve each of these challenges I-IV. The eventually devised solution proposes a combination of classical molecular dynamics (MD), followed by the hybrid QM/MM method ONIOM, which allows to combine the 'best of the QM and MM worlds' and is well established for other systems. To overcome challenge I, various effective core potentials (ECPs); basis sets; and density functionals are evaluated based on their ability to predict properties and geometries of several pristine AuNPs. These properties and geometries are either derived experimentally, or from high-level ab initio calculations. The chosen QM method PBE/LANL2DZ is then further tested on various systems, assessing its ability (challenge II) to reproduce hydrogen loss and staple formation. Upon proposing to tackle challenge III using ONIOM (with the OPLS-AA forcefield for the MM part), the method's performance is first compared to that of full QM (PBE/LANL2DZ) in terms of accuracy and efficiency, and in a variety of contexts, including on AuNPs featuring a 38-atom gold core. Once these calculations confirm the considerable time gains afforded by the introduction of ONIOM, I then demonstrate its full applicability in the optimisation of a large, experimentally plausible functionalised AuNP. Finally, I propose to tackle challenge IV by introducing a classical MD simulation stage to precede QM/MM optimisation. As a test, MD is used to generate statistically significant sets of 8-atom AuNPs coated with alkylthiols of different chain lengths, which are then optimised, thereby successfully reproducing the early stages of reconstruction. I then conclude by successfully testing this MD + ONIOM approach on two much larger functionalised AuNPs, having 20-atom gold cores and sixteen or seventeen 64-atom ligands. My Thesis highlights both the strengths and limitations of the ONIOM approach in simulating such a complex process as organosulfur self-assembly on AuNPs. Nonetheless, the chosen MD + ONIOM strategy can indeed reproduce key aspects of self-assembly with increased CPU-efficiency, and, importantly, makes electronically plausible predictions: it therefore represents a viable route for the in silico investigation of this process, and an encouraging fulfilment of my initial aim.
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Ogunlaja, Adeniyi Sunday. "Oxidative desulfurization of fuel oils-catalytic oxidation and adsorptive removal of organosulfur compounds." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1013152.
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The syntheses and evaluation of oxidovanadium(IV) complexes as catalysts for the oxidation of refractory organosulfur compounds in fuels is presented. The sulfones produced from the oxidation reaction were removed from fuel oils by employing molecularly imprinted polymers (MIPs). The oxidovanadium(IV) homogeneous catalyst, [V ͥ ͮ O(sal-HBPD)], as well as its heterogeneous polymer supported derivatives, poly[V ͥ ͮ O(sal-AHBPD)] and poly[V ͥ ͮ O(allylSB-co-EGDMA)], were synthesized and fully characterized by elemental analysis, FTIR, UV-Vis, XPS, AFM, SEM, BET and single crystal XRD for [V ͥ ͮ O(sal-HBPD)]. The MIPs were also characterized by elemental analysis, FTIR, SEM, EDX and BET. The catalyzed oxidation of fuel oil model sulfur compounds, thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT), was conducted under batch and continuous flow processes at 40°C by using tert-butylhydroperoxide (t-BuOOH) as oxidant. The continuous flow oxidation process presented the highest overall conversions and very high selectivity for sulfones. Maximum oxidation conversions of 71%, 89%, 99% and 88% was achieved for TH, BT, DBT and 4,6-DMDBT respectively when poly[V ͥ ͮ O(allylSB-co-EGDMA)] was employed at a flow-rate of 1 mL/h with over 90% sulfone selectivity. The process was further applied to the oxidation of hydro-treated diesel containing 385 ± 4.6 ppm of sulfur (mainly dibenzothiophene and dibenzothiophene derivatives), and this resulted to a high sulfur oxidation yield (> 99%), thus producing polar sulfones which are extractible by polar solid phase extractants. Adsorption of the polar sulfone compounds was carried-out by employing MIPs which were fabricated through the formation of recognition sites complementary to oxidized sulfur-containing compounds (sulfones) on electrospun polybenzimidazole (PBI) nanofibers, cross-linked chitosan microspheres and electrospun chitosan nanofibers. Adsorption of benzothiophene sulfone (BTO₂), dibenzothiophene sulfone (DBTO₂) and 4,6-dimethyldibenzothiophene sulfone (4,6-DMDBTO₂) on the various molecularly imprinted adsorbents presented a Freundlich (multi-layered) adsorption isotherm which indicated interaction of adsorbed organosulfur compounds. Maximum adsorption observed for BTO₂, DBTO₂ and 4,6-DMDBTO₂ respectively was 8.5 ± 0.6 mg/g, 7.0 ± 0.5 mg/g and 6.6 ± 0.7 mg/g when imprinted chitosan nanofibers were employed, 4.9 ± 0.5 mg/g, 4.2 ± 0.7 mg/g and 3.9 ± 0.6 mg/g on molecularly imprinted chitosan microspheres, and 28.5 ± 0.4 mg/g, 29.8 ± 2.2 mg/g and 20.1 ± 1.4 mg/g on molecularly imprinted PBI nanofibers. Application of electrospun chitosan nanofibers on oxidized hydro-treated diesel presented a sulfur removal capacity of 84%, leaving 62 ± 3.2 ppm S in the fuel, while imprinted PBI electrospun nanofibers displayed excellent sulfur removal, keeping sulfur in the fuel after the oxidation/adsorption below the determined limit of detection (LOD), which is 2.4 ppm S. The high level of sulfur removal displayed by imprinted PBI nanofibers was ascribed to hydrogen bonding effects, and π-π stacking between aromatic sulfone compounds and the benzimidazole ring which were confirmed by chemical modelling with density functional theory (DFT) as well as the imprinting effect. The home-made pressurized hot water extraction (PHWE) system was applied for extraction/desorption of sulfone compounds adsorbed on the PBI nanofibers at a flow rate of 1 mL/min and at 150°C with an applied pressure of 30 bars. Application of molecularly imprinted PBI nanofibers for the desulfurization of oxidized hydro-treated fuel showed potential for use in refining industries to reach ultra-low sulfur fuel level, which falls below the 10 ppm sulfur limit which is mandated by the environmental protection agency (EPA) from 2015.
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ASHBY, MICHAEL THOMAS. "THE NATURE OF ORGANOSULFUR LONE PAIR ORBITAL INTERACTIONS WITH TRANSITION METAL D-ORBITALS." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183814.
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This research has been directed at the study of organosulfur frontier orbital interactions with transition metal d-orbitals. Two novel thioether complexes tricarbonyl(1,4,7-trithiacyclononane)molybdenum(O) and tricarbonyl(2,5,8-trithianonane)molybdenum(O), have been prepared and structurally characterized by single crystal x-ray crystallography. The facial configuration of the carbonyl ligands provides a unique point of reference for describing the two polythioether ligands in terms of the free ligand's frontier orbitals. The relative carbonyl stretching frequencies of the two metal complexes indicate that 1,4,7-trithiacyclononane is a poorer donor than 2,5,8-trithianonane. This result is explained in terms of mechanical constraints placed on the mesocyclic polythioether which are absent in its acyclic analogue. The coordinatively unsaturated species (n⁵-C₅H₅)MO(NO)(SC₆H₅)₂ has been characterized by x-ray crystallography and its electronic structure has been modeled using Fenske-Hall molecular orbital calculations. The monomeric nature and chemical inertness of (n⁵-C₅H₅)MO(NO)(SC₆H₅)₂ are attributed to dπ-pπ bonding between the thiolate ligands and an empty molybdenum dπ orbital. The dπ-pπ interaction simultaneously strengthens the metal thiolate bond and makes the complex less susceptible to nucleophilic attack by raising the energy of the LUMO. The rotational orientations of the thiolate ligands observed in the solid state support this electronic model. For (n⁵-C₅H₅)Fe(CO)₂SR, the dπ-pπI antibonding interaction between the thiolate ligand and the metal has been modeled using Fenske-Hall molecular orbital calculations and experimentally investigated by photoelectron spectroscopy. The calculations predict that the HOMO is metal-sulfurn-antibonding and largely sulfur 3p in character. The observed HOMO ionization energies of (n⁵-C₅H₅)Fe(CO)₂SC₆H₄-p-Z; Z = OMe, H, Cl, CF₃, N0₂; correlate with several chemical properties including the rate of electrophilic attack on the sulfur by alkyl halides to give the thioether complex [(n⁵-C₅H₅)Fe(CO)₂(SR₂)]X and by electron-deficient alkynes to give the heterometallacycle (n⁵-C₅H₅)(CO)FeS(R)-C=C=C=0. The latter reaction is compared to the similar reaction of alkenes and alkynes with (n⁵-C₅H₅)Fe(CO)₂PR₂ to give (n⁵-C₅H₅)(CO)FeP(R)₂-C=C-C=0. X-ray crystal structures of one of the sulfur-containing and one of the phosphorus-containing heterometallacycles have been obtained.
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Chauvin, Jean-Philippe. "Elucidation of the Various Mechanisms of Antioxidant Activity of Organosulfur Compounds." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39675.
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Polysulfides, produced from olefin sulfurization, are common additives to various petroleum-derived products such as engine oils, hydraulic fluids, rubbers and polymeric materials in an effort to protect these materials from oxidative degradation. The mechanisms by which organosulfur compounds act as antioxidants are often described as ‘secondary antioxidants’ since it is believed that they slow the rate of radical initiation by decomposing hydroperoxides. Organosulfurs also figure in various natural products from the genus Allium, of which garlic is a prominent species. Our group previously shown that thiosulfinates (RS(O)SR), key components of garlic, are potent radical-trapping antioxidants (RTAs) through the intermediacy of sulfenic acids (RSOH). In an effort to shed light on the antioxidant mechanisms of other organosulfur constituents of garlic and sulfurized olefins, in Chapter 2, we reported on the antioxidant activity of trisulfide-1-oxides (RS(O)SSR) at 37 °C. In that study, we found these moieties to be effective RTAs, equal in potency to hindered phenols, the industry standard. Trisulfide-1-oxides were shown to react with peroxyl radicals via a concerted bimolecular homolytic substitution reaction, forming a perthiyl radical as product. In Chapter 3, inspired by the findings at 37 °C, we investigated the RTA activity of polysulfides at elevated temperatures, from 100 °C to 160 °C, and found that tetrasulfides were surprisingly potent RTAs at and above 100 °C. Paralleling the reactivity of trisulfide-1-oxides, tetrasulfides were found to react with peroxyl radicals via a concerted bimolecular homolytic substitution reaction, also forming a perthiyl radical as an initial product. Perthiyl radicals are formed in multiple reactions described in the abovementioned studies and although they were shown to rapidly recombine, their apparent stability, as well as preliminary computational investigations into the S-H bond strength in hydropersulfides (RSSH), prompted us to investigate hydrogen-atom transfers from hydropersulfides. As reported in Chapter 4, we found that hydropersulfides (RSSH) are very potent hydrogen-atom donors, making them highly effective RTAs in organic and aqueous media, even besting thiols in many H-atom transfer reactions with alkyl, alkoxyl and peroxyl radicals. The one-electron oxidation exhibited by hydropersulfides parallels the one we previously reported for sulfenic acids (RSOH). Previous successful studies on the one-electron oxidation of sulfenic acids prompted us to make use of the persistence imparted by a triptycene backbone to study two-electron processes, namely - thiol oxidation by hydrogen peroxide (H2O2). Indeed, the reaction of thiols with H2O2 is central to many processes essential to life, from protein folding to redox signaling. However, kinetic and mechanistic characterization of their subsequent reactions had not been reported due to the instability of the sulfenic acid intermediate under study. Gratifyingly, as reported in Chapter 5, using our triptycene model with an appended fluorine atom, we were able to investigate the complete series of consecutive reactions with hydrogen peroxide, from thiol to sulfenic acid to sulfinic acid to sulfonic acid, which has hitherto not been possible, and found that the reaction is specific base-catalyzed.
Sulfinic acids (RSO2H), the primary product of sulfenic acid oxidation, have been used increasingly in recent years in many synthetic applications such as sulfonylation reactions. As described in Chapter 6, using a similar approach to previous studies, we synthesized a triptycene sulfinic acid and demonstrated that the triptycene backbone is also effective a rendering the sulfinic acid and sulfonyl radical (RSO2•) persistent enough to study H-atom transfer reactions. We showed that sulfinic acids are good H-atom donors to alkyl and alkoxyl radicals but they are not effective RTAs due to the propensity of sulfinic acids to autoxidize through the reaction of sulfonyl radicals with oxygen.
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Nicolau, Manterola Felipe. "Hydrocarbon and insecticide induction of Beauveria bassiana catalysis of organosulfur compounds." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/3151.
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Catalysts are utilized in 80% of all chemical synthesis operations. The industrial catalysts primarily used in oxidation reactions are highly polluting and expensive metal catalysts. Enzymes and whole cell biocatalysts are used to a lesser extent. Nowadays, several industrial sectors are developing bio-based technologies to reduce the high costs and environmental impact of traditional chemical processes. However, these applications are limited by the challenge of developing economically competitive biologically based systems. The key for adopting these sustainable advancements is the development of novel process designs, which assure robustness, simplicity, and sustainabile operations compatible with the current development of chemical reactions. In this regard, filamentous fungi may be considered good biocatalysts due to their natural biodiversity and their broad heterogeneous enzymatic pattern. The great selectivity of fungal catalysis is now well recognized for the production of commercially valuable steroids in the pharmaceutical industry. Although this inherent capacity is mainly used for functionalization of unactivated carbons, it can be further exploited for the oxidiation of heteroatoms, such as sulfur. Focusing on the oxidation of sulfur compounds, the widely used industrial processes are produced by an organometallic catalyst. This PhD project aims to overcome low substrate conversion and enzymatic expression by proving that exposure of cells to insecticides and hydrocarbons increases cell's oxidative capacity expressed as higher substrate conversion and CYP450 content. This study is focused in the application of pest management strategies, designed to enhance the biopesticide's efficacy, to induce and improve Beauveria bassiana oxidation. B. bassiana has a very flexible metabolism and is widely used as a biocontrol agent. It can metabolize hexadecane as a sole carbon source. In addition, it shows a synergistic effect over pest control efficacy when it is applied with low pesticides (carbaryl and/or imidacloprid) concentrations.
A biocatalytic system was optimized to increase the conversion of organosulfur compounds under different fermentation conditions. Phenothiazine was used as our model substrate. Phenothiazine conversion was followed by GC-MS and HPLC. By NMR and MS fragmentation pattern product, phenothiazine metabolites were identified as (R)-hydroxyl metabolites (63% enatiomeric excess) and sulfoxide, the latter being the main metabolite. Phenothiazine conversions with growing cells resulted in 65±1.4% conversion with initial phenothiazine concentration of 500 ppm and final 325 ppm after 7 days. The highest conversion, 74±1 % was achieved with resting cells at the lowest cell concentration, 0.78 mg cell dry weight (cdw) /mL. Furthermore, the use of insecticides as inducers was an effective way to increase phenothiazine conversion from 47% to 64±3%. The major enzymes involved in catalysis of xenobiotic are heme-binding monooxygenases, in particular cytochrome P450. Heme positive proteins were identified by an SDS benzidine assay as well as the content of CYP450 by the CO difference spectrum. The P450 enzymes content was 12.3±1 pmol/µg protein for hexadecane adapted cells and 8.1± 1 pmol/µg protein for insecticides, respectively. The heme-positive proteins were characterized by MALDI-ToF and their peptide mass fingerprint compared to the available sequences on the SwissProt/Universal Protein Resource catalog of information on proteins (UniProtKB). Hemoproteins were found, including a cluster of catalase-peroxidase, alkane hydroxylase, and chloroperoxidase. The results from this project helped bridge the progress from agricultural biotechnology strain development into industrial biotechnology biocatalyst improvement. The success of this project helps us expand B. bassiana's catalysis and make it a better candidate for industrial biocatalysis.
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Low, Kam-hung, and 魯錦鴻. "Synthesis, structural characterization and applications of homoleptic organosulfur and organoselenium metal polymers." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43703859.
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Lachance, Russell Philip. "Oxidation and hydrolysis reactions in supercritical water : chlorinated hydrocarbons and organosulfur compounds." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/33533.
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Smith, Muneerah. "An investigation into the anti-cancer mechanism of garlic-related organosulfur compounds." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/12795.
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Includes abstract.~Includes bibliographical references.Crushed garlic contains organosulfur compounds (OSC), which are reported to have cancer chemotherapeutic properties both in vitro and in vivo. A library of 15 organosulfur analogues were obtained as mechanistic probes in WHCO1 oesophageal cancer cells. Structure-activity studies showed a positive correlation between the anti-proliferative-IC50 of disulfides and the relative stability of their anion leaving groups, as assessed through resonance and quantified by predictive pKa-values.
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Jin, Peng. "Mechanism of Corrosion by Naphthenic Acids and Organosulfur Compounds at High Temperatures." Ohio University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1384872234.
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Furuta, Satoru. "Synthetic Studies on Organofluorine Compounds through Oxidative Desulfurization -Fluorination of Organosulfur Compounds." Kyoto University, 2000. http://hdl.handle.net/2433/151524.
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DeCoste, Jared B. "Nucleophilic chemistry of faujasite X zeolites with isocyanates, organosulfur esters, and epoxides." Diss., Online access via UMI:, 2009.
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Low, Kam-hung. "Synthesis, structural characterization and applications of homoleptic organosulfur and organoselenium metal polymers." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43703859.
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Lorance, Edward Donald. "Synthetic and computational studies on organosulfur radical cations and alpha-metalated sulfides." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284212.
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The oxidation potentials and electrooxidation mechanism of 3,6-di substituted-1,2-dichalcogenins was investigated by cyclic voltammetry. An EC mechanism was found experimentally and the basis for the chemical step was found computationally to be a change in the planarity of the ring on electron transfer. Photoelectron spectra were obtained of 3,6-disubstituted-1,2-dichalcogenins a different ionizing photon energies. The interpretation of the photoelectron spectra was assisted by computational simulation. A narrow ionization band was found, and was assigned as the sulfur-sulfur σ orbital by computation and comparison of ionization cross-sections. Computational simulation of the excited state determined that this orbital is paired with a low-energy σ* orbital. Electronic transitions to the σ* orbital were found to be common in disulfides, and the low energy of the σ* orbital in 1,2-dichalcogenins causes their unusual color. The computed geometry of the excited state, coupled with ¹H NMR and ⁷⁷Se NMR data, also provided evidence of the limited anti-aromaticity of 1,2-dithiins. A systematic study of the α-deprotonation of dialkyl sulfides was made with Lochmann's/Schlosser's base. The products were analyzed by GC/MS, and the extent of both deprotonation and decomposition was assessed. Mechanisms of decomposition were evaluated. 4-tert-Butylthiane was alpha-deprotonated and stannylated in good yield, in a 38:1 cis:trans ratio. The oxidation potentials of various α-stannylated dialkyl sulfides were analyzed by cyclic voltammetry. The dependence of oxidation and ionization potential on the C-S-C-Sn dihedral angle was investigated computationally, and was found to obey a Karplus-Barfield-type relationship, with an ionization potential minimum near 90°. The computational predictions were borne out in the oxidation potential of cis-2-trimethylstannyl-4-tert-butylthiane (1.17 V), which was found to be slightly lower than the underivatized sulfide but much higher than other alpha-stannylated sulfides due to the 180°C-S-C-Sn dihedral angle. Various computational techniques were used to find evidence of the cyclic interaction of p-type lone pair orbitals in tetrathiatetraasterane. The neutral species and the radical cation were computationally predicted to be possess the same symmetry (D₄(h)) and cyclic interaction of sulfur lone pair orbitals, but oxidation to the dication was predicted to break a carbon-carbon bond.
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Tieman, Tamara L. "A Helium Discharge Detector for the Determination of Organosulfur and Phosphorus Compounds." W&M ScholarWorks, 1992. https://scholarworks.wm.edu/etd/1539625734.
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Otsuka, Shinya. "Studies on Catalytic Transformations of Organosulfur Compounds via C-S Bond Cleavage." Kyoto University, 2019. http://hdl.handle.net/2433/242625.
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Uhm, Hae Won. "Reaction of some chelating thioesters with chlorotris (triphenylphosphine) rhodium (I) : a model of the initial stages of hydrodesulfurization." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65413.
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PETSOM, AMORN. "SYNTHETIC AND MECHANISTIC STUDIES ON THE ELECTROOXIDATION OF ORGANIC THIOETHERS." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184178.
Full textAbstract:
This research has been directed at the study of neighboring group participation in electrooxidation of thioethers. Controlled potential oxidation of substituted 1,3-dithiane in wet acetonitrile provides substituted 1,2-dithiolane 1-oxide in good yield. Thioethers appended with neighboring alcohols and carboxylate are catalytically oxidized in a redox cycle by bromide ion. The formation of the alkoxysulfonium salt intermediates in such reactions is confirmed by product study. On the other hand, the acyloxysulfonium salt intermediates in the electrooxidation of endo -6-methylthio-bicyclo [2.2.1] heptane-2- endo -carboxylic acid (1) are unstable at room temperature. Control experiments using ¹⁸O labeled compounds prove unequivocally the existent of the acyloxysulfonium salt intermediates. Diastereospecific oxidation of 1 and its methyl ester with DABCO.2Br₂ complex and m-CPBA is sterically controlled. In both cases, similar product ratios are observed which is explained by the participation of the carboxylic acid group in the case of DABCO.2Br₂ oxidation but not in the case of m-CPBA oxidation. The structure of one of the diastereomer of the endo acid sulfoxide is unequivocally proved by x-ray crystallographic analysis.
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Webb, Jared A. "A Comparative Study of Anaerobic Digestion Processes for Sewage Sludge." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/41131.
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The Blue Plains Wastewater Treatment Plant in Washington, D.C. is in the process of updating its anaerobic digesters, with a completion date set for 2008. This research was undertaken to aid designers at Blue Plains by evaluating alternative digestion approaches. The technologies applicable to the plant included thermophilic anaerobic digestion, acid/gas phased digestion, and temperature phased anaerobic digestion. To obtain design data, a year long study was conducted using bench scale digestion systems operating at different solids retention times (SRT) and organic loading rates (OLR). The digesters were fed with mixed primary and secondary waste (50/50 by weight) from the Blue Plains wastewater treatment facility. The digesters were operated until they reached steady state as observed by volatile solids reduction (VSR), methane production, and volatile fatty acid (VFA) levels. At this point, samples of digested waste sludge were analyzed for residual biological activity, dewatering properties and headspace organo-sulfur production. Results from the study demonstrated that the TPAD digestion process had the lowest residual biological activity (RBA) after digestion, and that the single stage thermophilic digesters had the highest RBA. Sludge from single stage mesophilic digestion had the highest odor potential, with headspace gas tests generating over 1400 mg organo-sulfur per m3 of headspace gas, while both single stage thermophilic and TPAD systems generated less than 400 mg/m3 at all SRTs studied.Master of Science
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Morris, Stephen Arthur. "The oxidative-addition to some organosulfur compounds to bis (ð5-cyclopentadienyl) titanium (II) dicarbonyl /." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75828.
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Cp$ sb2$Ti(C))$ sb2$, where Cp = $ eta sp5$-cyclopentadienyl, reacted with RSSSR to give the catenated sulfur complexes Cp$ sb2$Ti(SR)(SSR), where R = CMe$ sb3$, CHMe$ sb2$, CH$ sb2$Ph, p-C$ sb6$H$ sb4$Me and CPh$ sb3$. These complexes, except for R = CPh$ sb3$, reacted with PhCH$ sb2$Br to give Cp$ sb2$TiBr$ sb2$, PhCH$ sb2$SR and PhCH$ sb2$SSR as major products. Cp$ sb2$Ti(SR)(SSR) desulfurized slowly in solution and rapidly in the presence of Ph$ sb3$P, giving Cp$ sb2$Ti(SR)$ sb2$ and Ph$ sb3$PS, in addition to other species. Similarly, phth-SSR, where phth = phthalimide, oxidatively added to Cp$ sb2$Ti(CO)$ sb2$ to give Cp$ sb2$Ti(X)(SSR), where X = phth and R = CMe$ sb3$, CHMe$ sb2$, CH$ sb2$Ph and p-C$ sb6$H$ sb4$Me. Solvolysis by MeOH and EtOH gave the species where X = OMe and OEt. In a similar manner Ph$ sb3$CSSCl added to Cp$ sb2$Ti(CO)$ sb2$ to give Cp$ sb2$Ti(Cl)(SSCPh$ sb3$). Treatment of Cp$ sb2$Ti(SR)(SSR) with (norbornadiene)Mo(CO)$ sb4$ gave the bridged dimers, (Cp$ sb2$Ti($ mu$-SR)-($ mu$-S$ sb{ rm x}$R)Mo(CO)$ sb4$), where x = 1 and 2 and R = CMe$ sb3$ and CHMe$ sb2$. The complexes where x = 2 contained the rare iso-$ mu$-$ eta sp1$-SSR ligand. In solution at low temperatures the bridging thiolato and disulfano groups were predominantly transoid. At higher temperatures, a dynamic process that allowed averaging of cyclopentadienyl ring environments took place. $ sp1$H NMR studies permitted evaluation of $ Delta{ rm G sbsp{c}{ ddagger}}$ for the averaging process.
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Zecchini, M. "Synthesis of new substituted organosulfur donors for the preparation of conductive and multifunctional materials." Thesis, Nottingham Trent University, 2015. http://irep.ntu.ac.uk/id/eprint/27926/.
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The work presented in this thesis focused on the preparation of three main type of compounds: i) bridged dimeric BEDT-TTF donors (chapter 2), ii) enantiopure substituted EDT-TTF donors with hydrogen bonding functionalities (chapter 3) and iii) BEDT-TTF substituted ligands and their ability to form multifunctional materials (chapter 4). In chapter 2 the preparation of novel BEDT-TTF donors containing an alkene in the side such as (I) and (II) is reported. Single crystals of oxidised material have been prepared and conductivities have been measured. A radical cation salt of (I) with I2/I3 was found to be a semiconductor at r.t. [Figure 1. Donors containing an alkene functionality on the side chain.]. The preparation of dimeric BEDT-TTFs such as (III) has been investigated using different substrates and strategies but the reactivity towards the second cyclisation was found to be the issue. [Figure 2. Desired dimer system (III).]. The chapter 3 contains the preparation of novel enantiopure EDT-TTF derivatives, whose side chains were designed to guide the packing in the solid state by involving non-covalent interactions such as hydrogen bonding and/or additional π-π stacking interactions as in donors (IV) and (V). [Figure 3. Examples of enantiopure donors prepared in chapter 3.]. In chapter 4 the investigation of the coordination chemistry of novel BEDT-TTF substituted ligand (VI) with first row transition metals has started. The magnetism of some of the new complexes formed has been measured. [Figure 4. Type of BEDT-TTF ligands designed for metal complexes preparation.].
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Svarovsky, Serge A. "Structure, stability and reactivity of small organic sulfinic and sulfonic acids toxicological implications ; Role of charge transfer complexes in oxidation cleavage of benzpinacols by iron (III) trispenanthroline /." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1231.
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Reese, Raymond Scott. "Self-assembled monolayers of organosulfur compounds on gold incorporating terminal conjugated arenes, redox active probes, and oligonucleotides /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Chiu, Winnie Wai Hang. "Metal complexes with sulfur and selenium donor ligands /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202009%20CHIU.
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Ryan, M. Dominic (Michael Dominic). "Organopolychalcogenides, new bond energy results and synthesis via the first selenium transfer reagent." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75753.
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Reevaluation of organosulfur heats of formation resulted in the conclusion that the sulfur-sulfur bond of aliphatic disulfides is nearly 15 Kcal/mole stronger than the disulfide carbon-sulfur bond energy. Semi-empirical calculations using AM1, MNDO and MINDO/3 from the AMPAC program package confirmed these results and clarified their relative impact on organosulfide and disulfide properties.Existing organoselenium bond energy data were also reevaluated and erroneous assumptions discovered. New bond energy estimates were made via a new procedure. It was concluded that the selenium-selenium bond is also stronger than the selenium-carbon of aliphatic diselenides.
The above results led to the conclusion that loss of molecular dichalcogen from molecules such as disulfides or diselenides is favored over the stepwise loss of a single chalcogen by about 40 Kcal/mol. Loss of molecular diselenium from dibenzyl diselenide is reported. The average carbon-selenium bond energy of the latter is calculated to be only 27 Kcal/mol.
The preparation of 2-thiatriselenides (RSeSSeR) and 2,3-dithiatetraselenides (RSeSSSeR) has been achieved from selenosilanes. The products were characterized by $ sp{77}$Se NMR and the trends of chemical shifts were analyzed.
The preparation of the first selenium transfer reagents, including the first unsymmetrical chalcogen transfer reagent, is reported. Their use to effect the synthesis of 2-selenatrisulfides (RSSeSR) is also reported. Low temperature $ sp{77}$Se NMR was used to elucidate the reaction mechanism and characterize several intermediates such as selenuranes, selenonium ions and azole selenides. In addition, 2,3-diselenatetrasulfides (RSSeSeSR) were characterized by $ sp{77}$Se NMR.
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Chen, Xiangke. "Vibrational Sum Frequency Generation Studies of Biological and Atmospheric Relevant Interfaces: Lipids, Organosulfur Species and Interfacial Water Structure." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1282061999.
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Inami, Tasuku. "Studies on Nickel-Catalyzed Reactions via Alkyne Insertion into Carbon-Sulfur Bonds." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199274.
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Atkinson, Sarah Jane, and n/a. "Studies in Dendritic Scaffolds and Surface Functionalisation for Applications in Nanoscience." Griffith University. School of Biomolecular and Physical Sciences, 2007. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20071122.124705.
Full textAbstract:
Chapter 1 includes a review on dendrimers, their synthesis and applications, with a particular focus on urea-linked dendritic species. The synthetic strategy utilised in this body of work was based on the preparation of a number of branched synthetic building blocks possessing differing terminal functionality. These branched dendrons, bearing three terminal residues and based on the cheap starting material tris(hydroxymethyl)aminomethane (TRIS) 23, involved the coupling of 3.3 equivalents of an appropriately para-substituted benzoic acid chloride with BOC protected TRIS 24 in DCM in the presence of triethylamine. The p-nitro, p-methoxy and p-methyl benzoyl chloride starting materials were obtained commercially, whilst N-(4-carboxyphenyl)maleimide was synthesised according to literature procedures. The BOC protected dendrons (2527, 34) were synthesized in yields ranging from 5092%. Deprotection of the BOC protected dendrons 25 and 26 in DCM with TFA, followed by the addition of 1M Na2CO3 afforded the TFA salts 35 and 36, respectively. The corresponding free base amines 37 and 38 were obtained on further treatment of the TFA salts with sodium carbonate. Deprotection of the BOC protected dendrons 27 and 34 afforded the free amines 39 and 48 directly after treatment with sodium carbonate. Synthesis of functionalised branched molecules containing 6- and 9-peripheral functionalities was achieved by refluxing 2 or 3 equivalents of the free amine dendrons with the bi- or tri- functional isocyanate cores, 15 and 45, in refluxing DCM, in most cases the products precipitated from the reaction mixture after 18 h and were isolated simply by filtration, otherwise the removal of the solvent from the reaction mixture afforded the spectroscopically pure product. Conversion of the peripheral nitro functionalised species 14 and 21 to the corresponding amines occurred smoothly via hydrogenation using 5% Pd/C under elevated temperature and pressure (DMF, 55 ºC, 600 psi) and afforded the polyamine 6-mer 51 in 92% yield and the 9-mer 50 in 90% yield, respectively. Similarly, conversion of the methoxy coated 9-mer 42, to the corresponding phenolic compound (AlBr3, dodecane thiol, DCM) afforded the 9-mer polyphenol 52 in an 87% yield. All compounds prepared were fully characterised and crystal structures were obtained for 26 and 35. Chapter 2 includes a review on self-assembled monolayers of organosulfur compounds on gold, applications, patterning techniques and techniques for the characterisation of these surfaces. A number of surface monomers were successfully synthesized, to be used for various surface functionalisations, including the formation of an amine reactive N-hydroxysuccinimide (NHS) disulfide 53, via the DCC coupling of 11,11-dithiobisundecanoic acid 54 with N-hydroxysuccinimide with an isolated yield of 30%. A novel protein-resistant monomer 58 was also synthesized from 11-undecanoic acid 55 via an acid chloride coupling with triethylene glycol monomethyl ether 58, and isolated in a 72% yield. A number of attempts were made to produce an acyl azide SAM monomer 59, with success finally achieved via the acid chloride coupling of 11,11-dithiobisundecanoic acid 54 with 5-amino-1,3-benzenedicarbonyl diazide 62 to produce 59 with an isolated yield of ~ 30%. Gold surfaces were prepared on atomically flat silicon wafers using an argon-ion sputterer. SAM films were formed on the gold surfaces via traditional solution based self-assembly methodology. A UV patterning protocol was developed, and a successful patterning trial using the NHS terminated monomer to backfill the UV exposed areas of a dodecane thiol monolayer was achieved and visualized using AFM and fluorescence microscopy after treating the surface with aminofluorescein. The covalent attachment of green fluorescent protein to the monolayer surface via reaction with the NHS terminated monolayer was demonstrated. The fluorescence of the biomolecule was preserved. The formation of a monolayer using the acyl azide monomer 59, was characterised by contact angle and XPS analysis. However, preliminary studies into the activation of the acyl azide surface into the reactive isocyanate were unsuccessful. There is however, significant scope for further investigations into this interesting surface technology. Chapter 3 includes a review on heterobifunctional linker technology with a particular focus on amine and thiol reactive moieties and literature examples of heterobifunctional linkers of this type. Synthesis of heterobifunctional reagents such as 71 and 74 via a two step synthetic methodology involving the coupling of maleic anhydride with the parent amino-acids in acetic acid, followed by a one pot cyclisation and NHS esterification using DCC in DMF were successful, with overall yields of 9% and 32% respectively for the two reaction steps. The one pot extension of 74 with 6-aminohexanoic acid, followed by DCC, facilitated NHS esterification was achieved successfully in a yield of 30%. Attempts to extend 74 with the synthesised amino acid 88 were unsuccessful due to the insolubility of 88 in organic solvents. A different synthetic strategy was devised towards the synthesis of 85 with the coupling of 74 and mono BOC protected ethylene diamine 91 in DCM to give 93 in an isolated yield of 60%. Deprotection of the terminal amine was achieved via reaction with TFA in DCM however all attempts to prepare the free amine were unsuccessful. Subsequent attempts to couple 94 with both succinic anhydride and 92 were unsuccessful. A maleimide functionalized crown ether was synthesised as a molecule for protein modification via the reaction of 74 with 4-aminobenzo-15-crown-5 97 to produce 98 in an 80% yield. All compounds were fully characterised with crystal structures obtained for 74, 79 and 89.
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Atkinson, Sarah Jane. "Studies in Dendritic Scaffolds and Surface Functionalisation for Applications in Nanoscience." Thesis, Griffith University, 2007. http://hdl.handle.net/10072/366865.
Full textAbstract:
Chapter 1 includes a review on dendrimers, their synthesis and applications, with a particular focus on urea-linked dendritic species. The synthetic strategy utilised in this body of work was based on the preparation of a number of branched synthetic building blocks possessing differing terminal functionality. These branched dendrons, bearing three terminal residues and based on the cheap starting material tris(hydroxymethyl)aminomethane (TRIS) 23, involved the coupling of 3.3 equivalents of an appropriately para-substituted benzoic acid chloride with BOC protected TRIS 24 in DCM in the presence of triethylamine. The p-nitro, p-methoxy and p-methyl benzoyl chloride starting materials were obtained commercially, whilst N-(4-carboxyphenyl)maleimide was synthesised according to literature procedures. The BOC protected dendrons (25–27, 34) were synthesized in yields ranging from 50–92%. Deprotection of the BOC protected dendrons 25 and 26 in DCM with TFA, followed by the addition of 1M Na2CO3 afforded the TFA salts 35 and 36, respectively. The corresponding free base amines 37 and 38 were obtained on further treatment of the TFA salts with sodium carbonate. Deprotection of the BOC protected dendrons 27 and 34 afforded the free amines 39 and 48 directly after treatment with sodium carbonate. Synthesis of functionalised branched molecules containing 6- and 9-peripheral functionalities was achieved by refluxing 2 or 3 equivalents of the free amine dendrons with the bi- or tri- functional isocyanate cores, 15 and 45, in refluxing DCM, in most cases the products precipitated from the reaction mixture after 18 h and were isolated simply by filtration, otherwise the removal of the solvent from the reaction mixture afforded the spectroscopically pure product. Conversion of the peripheral nitro functionalised species 14 and 21 to the corresponding amines occurred smoothly via hydrogenation using 5% Pd/C under elevated temperature and pressure (DMF, 55 ºC, 600 psi) and afforded the polyamine 6-mer 51 in 92% yield and the 9-mer 50 in 90% yield, respectively. Similarly, conversion of the methoxy coated 9-mer 42, to the corresponding phenolic compound (AlBr3, dodecane thiol, DCM) afforded the 9-mer polyphenol 52 in an 87% yield. All compounds prepared were fully characterised and crystal structures were obtained for 26 and 35. Chapter 2 includes a review on self-assembled monolayers of organosulfur compounds on gold, applications, patterning techniques and techniques for the characterisation of these surfaces. A number of surface monomers were successfully synthesized, to be used for various surface functionalisations, including the formation of an amine reactive N-hydroxysuccinimide (NHS) disulfide 53, via the DCC coupling of 11,11’-dithiobisundecanoic acid 54 with N-hydroxysuccinimide with an isolated yield of 30%. A novel protein-resistant monomer 58 was also synthesized from 11-undecanoic acid 55 via an acid chloride coupling with triethylene glycol monomethyl ether 58, and isolated in a 72% yield. A number of attempts were made to produce an acyl azide SAM monomer 59, with success finally achieved via the acid chloride coupling of 11,11’-dithiobisundecanoic acid 54 with 5-amino-1,3-benzenedicarbonyl diazide 62 to produce 59 with an isolated yield of ~ 30%. Gold surfaces were prepared on atomically flat silicon wafers using an argon-ion sputterer. SAM films were formed on the gold surfaces via traditional solution based self-assembly methodology. A UV patterning protocol was developed, and a successful patterning trial using the NHS terminated monomer to backfill the UV exposed areas of a dodecane thiol monolayer was achieved and visualized using AFM and fluorescence microscopy after treating the surface with aminofluorescein. The covalent attachment of green fluorescent protein to the monolayer surface via reaction with the NHS terminated monolayer was demonstrated. The fluorescence of the biomolecule was preserved. The formation of a monolayer using the acyl azide monomer 59, was characterised by contact angle and XPS analysis. However, preliminary studies into the activation of the acyl azide surface into the reactive isocyanate were unsuccessful. There is however, significant scope for further investigations into this interesting surface technology. Chapter 3 includes a review on heterobifunctional linker technology with a particular focus on amine and thiol reactive moieties and literature examples of heterobifunctional linkers of this type. Synthesis of heterobifunctional reagents such as 71 and 74 via a two step synthetic methodology involving the coupling of maleic anhydride with the parent amino-acids in acetic acid, followed by a one pot cyclisation and NHS esterification using DCC in DMF were successful, with overall yields of 9% and 32% respectively for the two reaction steps. The one pot extension of 74 with 6-aminohexanoic acid, followed by DCC, facilitated NHS esterification was achieved successfully in a yield of 30%. Attempts to extend 74 with the synthesised amino acid 88 were unsuccessful due to the insolubility of 88 in organic solvents. A different synthetic strategy was devised towards the synthesis of 85 with the coupling of 74 and mono BOC protected ethylene diamine 91 in DCM to give 93 in an isolated yield of 60%. Deprotection of the terminal amine was achieved via reaction with TFA in DCM however all attempts to prepare the free amine were unsuccessful. Subsequent attempts to couple 94 with both succinic anhydride and 92 were unsuccessful. A maleimide functionalized crown ether was synthesised as a molecule for protein modification via the reaction of 74 with 4’-aminobenzo-15-crown-5 97 to produce 98 in an 80% yield. All compounds were fully characterised with crystal structures obtained for 74, 79 and 89.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Physical Sciences
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Souza, Frederico Bernardes de. "Síntese e funcionalização de compostos organoenxofre: sulfóxidos, sulfetos e N-sulfinil iminas." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/9/9138/tde-19102017-155658/.
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Neste trabalho promovemos a síntese de sulfóxidos vinílicos ?-substituídos através da reação de acoplamento cruzado de Suzuki-Miyaura. Também foi feita a síntese de sulfóxidos enínicos inéditos, pela adição do nucleófilo no carbono β-sulfóxido. Esses compostos eram passíveis de serem submetidos a reação de rearranjo de Pummerer aditivo e assim gerarem uma pequena biblioteca de compostos α-tioaldeídos. Um desses aldeídos sintetizados foi empregado na reação de formação de uma imina propargílica, com consequente reação de CuAAC formando iminas triazólicas. Outras iminas arílicas foram sintetizadas, passando por uma etapa de redução, com intuito de se obter a amina livre, para que fosse feita a reação de ciclização com auxílio de um agente eletrofílico. Outra classe de composto organoenxofre foi sintetizada, as N-sulfinil imina, que após a reação de acoplamento cruzado de Sonogashira, com consequente remoção de um grupo protetor e a formação do anel heterocíclico, foram obtidos compostos triazólicos N-sulfinil imínicos.In this work we promote the synthesis of α-substituted vinylic sulfoxides through the Suzuki-Miyaura cross coupling reaction. Also the synthesis of unpublished enynic sulfoxides was made, by the addition of the nucleophile in the β-sulfoxide carbon. These compounds were susceptible to additive Pummerer rearragement reaction and thus generated a small library of compounds. One of these aldehydes synthesized was used in the formation reaction of a propargyl imine, with consequent CuAAC reaction, forming triazol imines. Other aryl imines were synthesized, undergoing a reduction step, in order to obtain the free amine, so that the cyclization reaction was carried out with the aid of an electrophilic agent. Another class of organosulfur compound was synthesized, the N-sulfinyl imine, which after the Sonogashira cross-coupling reaction, with consequent removal of a protecting group and formation of the heterocyclic ring, N-sulfinyl imine triazolic compounds were obtained.
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Maclellan, Paul William. "Asymmetric synthesis of tertiary thiols by lithiation of thiocarbamates." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/asymmetric-synthesis-of-tertiary-thiols-by-lithiation-of-thiocarbamates(ee91a5d1-63ba-458b-87bc-fd32e7c27b96).html.
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Tertiary thiols are a synthetically challenging class of compounds to prepare asymmetrically. The few reported methods for preparing these species require restrictive functionality to be incorporated into the products or are limited to employing simple carbon electrophiles. This thesis details investigations into the lithiation of N-aryl thiocarbamates. A stereoselective intramolecular arylation within lithiated thiocarbamates has been developed allowing the construction of quaternary stereocentres next to sulfur. Simple deprotection allows the isolation of enantiomerically pure tertiary thiols. A procedure for aryl migration within benzylic thiocarbamates has been developed and optimised. Rearrangement occurs in good yield and excellent stereoselectivity in a wide range of thiocarbamate substrates. Various substitution patterns are tolerated on the migrating aryl ring, the benzylic aryl ring and on the benzylic carbon centre. Extension of this methodology has incorporated an asymmetric alkylation of achiral benzylic thiocarbamates as a method of preparing aryl migration substrates. This allows the asymmetric synthesis of tertiary thiols in 2 steps from simple achiral precursors. Aryl migration has also been found to occur in lithiated allylic thiocarbamates with high stereospecificity, allowing preparation of a wider range of tertiary thiols.
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Hitchcock, Jessica Kaari. "The immunomodulatory effects of the garlic organosulfur compounds allicin and Z-ajoene in an in vitro murine model of LPS-induced inflammation." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/15735.
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Cancer is a leading cause of death in the modern world. Chronic inflammation facilitates tumourigenesis and cancer progression by providing an environment conducive to cancer. Dysregulation of the immune response, and particularly inflammation, is an important part of this process. Garlic (Allium sativum) has been used for centuries as both a prophylactic and therapeutic medicinal agent, more recent epidemiological and experimental evidence shows that garlic has both cancer-preventative and immune system-enhancing effects. While garlic contains many bioactive compounds, garlic organosulfur compounds (OSCs) have been most widely studied for their anti-cancer properties. In this study, we hypothesize that garlic OSCs modulate the inflammatory immune response by downregulating pro-inflammatory while stimulating anti-inflammatory responses, preventing the formation of a cancer-friendly chronic inflammatory environment. To test this hypothesis we established and optimised an in vitro inflammatory model using lipopolysaccharide-stimulated RAW264.7 murine macrophages. Expression analysis of selected inflammatory genes was performed by qPCR on RNA harvested 4 h and 8 h post treatment, while protein expression was analysed by ELISA using cell culture supernatant samples harvested 8 h and 24 h post treatment. These experiments were complemented by gene and protein arrays. Results showed that allicin had a more pronounced upregulatory effect on LPS-induced gene expression 4 h post-LPS treatment. In contrast, Z-ajoene generally had mild downregulatory effects on the expression of LPS-induced genes. Conversely, Z-ajoene had pronounced downregulatory effects on LPS-induced inflammatory proteins after 24 h, while allicin showed mild up- or downregulatory effects. Overall, we found that allicin induced an initial pro-inflammatory gene response, while Z-ajoene induced a longer-lasting anti-inflammatory response at a protein level. Finally, as many of the inflammatory genes investigated are regulated by the transcription factor STAT3, we investigated the effects of allicin and Z-ajoene on STAT3 phosphorylation and hence activation. Western blot analyses showed that allicin increased LPS-induced STAT3 phosphorylation (2-8 h), while Z-ajoene was found to decrease the phosphorylation of STAT3 after 4 h. These effects on STAT3 phosphorylation are in agreement with the early pro-inflammatory effect of allicin and the later anti-inflammatory effect of Z-ajoene on LPS-induced gene and protein expression. Further, using Western blotting we showed that E/Z-ajoene directly interacts with and reversibly alkylates STAT3 via a thiol-disulfide reaction with a cysteine thiolate on STAT3.
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Battin, Erin E. "The role of metal coord[i]nation in the inhibition of iron(ii)- and copper(i)-mediated DNA damage by organoselenium and organosulfur compounds." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1219862989/.
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Dannenberg, Carl A. Verfasser], Carsten [Akademischer Betreuer] [Bolm, and Dieter [Akademischer Betreuer] Enders. "Method development for the synthesis of organosulfur compounds and their functionalization by C–H activation and reductive borylation / Carl A. Dannenberg ; Carsten Bolm, Dieter Enders." Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/1156924286/34.
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Ulivi, Paola <1975>. "Activity and mechanisms of action of novel organosulfur derivatives of the HDAC inhibitor Valproic Acid in human experimental models of non-small-cell lung cancer." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6310/.
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Non-small-cell lung cancer (NSCLC) represents the leading cause of cancer death worldwide, and 5-year survival is about 16% for patients diagnosed with advanced lung cancer and about 70-90% when the disease is diagnosed and treated at earlier stages.
Treatment of NSCLC is changed in the last years with the introduction of targeted agents, such as gefitinib and erlotinib, that have dramatically changed the natural history of NSCLC patients carrying specific mutations in the EGFR gene, or crizotinib, for patients with the EML4-ALK translocation. However, such patients represent only about 15-20% of all NSCLC patients, and for the remaining individuals conventional chemotherapy represents the standard choice yet, but response rate to thise type of treatment is only about 20%. Development of new drugs and new therapeutic approaches are so needed to improve patients outcome.
In this project we aimed to analyse the antitumoral activity of two compounds with the ability to inhibit histone deacethylases (ACS 2 and ACS 33), derived from Valproic Acid and conjugated with H2S, in human cancer cell lines derived from NSCLC tissues.
We showed that ACS 2 represents the more promising agent. It showed strong antitumoral and pro-apoptotic activities, by inducing membrane depolarization, cytocrome-c release and caspase 3 and 9 activation. It was able to reduce the invasive capacity of cells, through inhibition of metalloproteinases expression, and to induce a reduced chromatin condensation. This last characteristic is probably responsible for the observed high synergistic activity in combination with cisplatin.
In conclusion our results highlight the potential role of the ACS 2 compound as new therapeutic option for NSCLC patients, especially in combination with cisplatin. If validated in in vivo models, this compound should be worthy for phase I clinical trials.
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Gomes, Sónia Maria. "Catalytic oxidation of organic compounds : a sustainable approach." Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14892.
Full textAbstract:
Doutoramento em QuímicaOne of the biggest challenges for organic chemistry researchers is the development of catalytic systems able to selectively oxidize organic compounds, under mild and environmental sustainable conditions. In fact, this is a transformation which nature operates with an extraordinary ability but is of remarkable difficulty for both academia and industry. Metalloporphyrins, as biomimetic models of cytochromes P450, are thus catalysts with great potential. After the first introductory chapter, where the above-mentioned concepts are fully discussed, some general features of porphyrin properties, synthetic methodologies and reactivity are presented in Chapter 2 of this dissertation. The synthetic routes to all the Mn(III) and Fe(III) porphyrins used as catalysts during the work are also discribed in this chapter. Chapter 3 is dedicated to the application of Mn(III) and Fe(III) metalloporphyrin complexes on the oxidative catalysis of organosulfur compounds (sulfides, benzothiophenes, dibenzothiophenes and 1,3-di-hydrobenzothiophenes) by hydrogen peroxide. Besides revealing a high efficient approach for the obtention of the corresponding sulfones, the use of mild and nontoxic conditions turns this approach environmentally safe. The potentiality of the developed methodology only can be fully recognized through the heterogenization of porphyrin complexes in a solid support. So, in chapter 4 the immobilization strategies of tetrapyrrolic macrocycles onto Merrifield resin and silica supports are presented. Three heterogeneous metalloporphyrin-based materials were prepared and the results of catalytic assays with thioanisole as substrate and H2O2 as oxidant put in evidence the efficiency and recyclability of two of them. The catalytic experiments with metalloporphyrins were extended to other substrate classes, namely benzofurans and naphtoquinones, and the results are described and discussed in Chapters 5 and 6, respectively. Despite the complexity of the products obtained, the preferential oxidation route in both cases seems to involve first an epoxidation. Finally, the efficiency of two non-porphyrinic catalysts, namely a manganese polyoxometalate and graphene oxide (tested under homogeneous and heterogeneous conditions, respectively), was also evaluated in sulfoxidation processes by hydrogen peroxide, being the results described in Chapter 7. Graphene 3D oxide, whose catalytic performance was evaluated for the first time, demonstrates to be efficient and recyclable in the oxidation of thioanisole. The last chapter includes some general conclusions and future perspectives for the developed work.
Um dos maiores desafios para os investigadores da área da química orgânica prende-se com o desenvolvimento de sistemas catalíticos capazes de promover, mesmo sob condições moderadas e ambientalmente sustentáveis, a oxidação selectiva de compostos orgânicos. Esta é uma transformação que a natureza realiza de uma forma extraordinária mas que se reveste de tremenda dificuldade tanto no meio académico como a nível industrial. As metaloporfirinas, consideradas modelos biomiméticos do citocromo P450, revestem-se por isso de um enorme potencial em catálise. Assim, nesta dissertação, após o primeiro capítulo introdutório, onde os conceitos mencionados acima são apresentados, no capítulo 2 são abordados alguns dos principais aspectos relativos às propriedades, síntese e reactividade das porfirinas. São ainda descritas neste capítulo as rotas sintéticas para todas as metaloporfirinas de Mn(III) e de Fe(III) usadas durante o trabalho. O capítulo 3 reporta-se à aplicação de complexos metaloporfirínicos de Mn(III) e de Fe(III) na catálise oxidativa de compostos organosulfurados (sulfuretos, benzotiofenos, dibenzotiofenos e 1,3-di-hidrobenzotiofenos) pelo peróxido de hidrogénio. Para além de se revelar uma metodologia altamente eficiente para a obtenção das correspondentes sulfonas, o uso de condições moderadas e atóxicas, torna esta abordagem segura para o meio ambiente. A potencialidade da metodologia desenvolvida só pode ser amplamente reconhecida através da heterogeneização do complexo porfirínico num suporte sólido. Desta forma, no capitulo 4 são apresentadas as estratégias de imobilização de diferentes macrociclos tetrapirrólicos na resina de Merrifield e na sílica funcionalizada. Foram preparados três materiais baseados em metaloporfirinas e os resultados dos ensaios catalíticos envolvendo o tioanisol como substrato e como oxidante o H2O2 colocam em evidência a eficiência e a reciclabilidade de dois deles. Os ensaios catalíticos com metaloporfirinas foram alargados a outras classes de substratos, nomeadamente os benzofuranos e as naftoquinonas, cujos resultados se apresentam nos capítulos 5 e 6, respectivamente. Apesar da complexidade de produtos obtida, a preferencial via de oxidação parece envolver, em ambos os casos, em primeiro lugar uma epoxidação. Finalmente, foi ainda avaliada a eficiência de dois catalisadores não porfirínicos, nomeadamente um polioxometalato e um óxido de grafeno (testados em condições homogéneas e heterogéneas respectivamente) em processos de sulfoxidação pelo peróxido de hidrogénio, cujos resultados se descrevem no capitulo 7. O último capítulo inclui as conclusões gerais e algumas perspectivas futuras para o trabalho desenvolvido.
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Halpern, Melissa Dale. "The in vivo and in vitro effects of diethyldithiocarbamate on autoimmune New Zealand Black/White F₁ hybrid, MRL/Mp-lpr/lpr and related and normal murine strains." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184940.
Full textAbstract:
New Zealand Black/White F₁ hybrid (NZB/W) and MRL/Mp-lpr/lpr (MRL/lpr) mice spontaneously develop a Systemic Lupus Erythematosus-like autoimmune disease. While the primary immunologic defect in the NZB/W is due to B cells, in the MRL/lpr it is a result of T cell abnormalities. Diethyldithiocarbamate (DTC), an agent suggested to enhance T cell function, was used to treat both strains. Weekly treatment of NZB/W mice with 25 mg/kg DTC had no significant effect upon survival or autoantibody levels but did induce changes in cell surface antigen expression. MRL/lpr mice treated with DTC displayed normalization of cell surface antigen expression (particularly increased expression of Lyt-2, macrophage markers and Lyt-2⁺/L3T4⁺ thymocytes), decreased lymphoproliferation and thymic atrophy, decreased serum autoantibody levels and kidney deposition of C3 and IgM, restored responses to mitogens and significantly prolonged survival. To determine both the influence of MRL background and lpr genes and to better understand on what cell populations DTC effects, changes in cell surface antigen expression were examined in DTC treated MRL-+/+, Balb/c, and Balb/lpr strains. The only consistent similarities observed between all strains tested were DTC induced changes in Mac-1 splenocyte surface antigen expression. In vitro studies showed DTC to have variable effects upon the mitogenic responses of lymphoid cells to phytohemagluttinin, but DTC alone stimulated both MRL/lpr and Balb/lpr lymphocytes. DTC stimulated the null cell population that predominates in lpr gene-bearing mice, but all observed in vitro effects of DTC were dependent upon the adherent cell population included in culture. DTC had no apparent direct effects upon adherent cells alone however. These studies have shown that DTC is capable of positive effects upon one autoimmune murine strain, the MRL/lpr, but not the NZB/W. DTC appears to affect macrophages, but other cell populations are required to obtain full activity of this compound. The variable effects of DTC emphasize the need to define the immunopathology of individual patients with autoimmune disease before initiating treatment with immunomodulative therapy.
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Zhu, Lei. "Aqueous phase reaction kinetics of organic sulfur compounds of atmospheric interest." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-11172004-142820/unrestricted/zhu%5Flei%5F200412%5Fphd.pdf.
Full textAbstract:
Thesis (Ph. D.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2005.Davis, Douglas, Committee Member ; Huey, Greg, Committee Member ; Nenes, Athanasios, Committee Member ; Weber, Rodney, Committee Member ; Whetten, Robert, Committee Member ; Wine, Paul H., Committee Chair. Includes bibliographical references.
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Yin, Fangdong Seinfeld John H. "Atmospheric photooxidation of organosulphur compounds /." Diss., Pasadena, Calif. : California Institute of Technology, 1990. http://resolver.caltech.edu/CaltechETD:etd-11192007-092214.
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Monin, Guillaume. "Stabilisation chimique des électrolytes polymères pour pile à combustible." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00728176.
Full textAbstract:
La dégradation accélérée des membranes conductrices protoniques en pile est en partie due à une oxydation induite par la production d'H2O2. Cette étude présente une stratégie originale de stabilisation chimique d'une matrice de sPEEK par l'inclusion de nano-charges stabilisantes. Quatre nano-charges ont été préparées par fonctionnalisation de nanoparticules de silice avec des fonctions chimiques organosoufrées (disulfure, tétrasulfure et thiourée). Un protocole spécifique de mise en forme des membranes hybrides a permis d'obtenir des composites présentant des propriétés mécaniques et une conductivité protonique compatibles avec l'application pile. Les fonctions polysulfures permettent de ralentir la dégradation de la matrice de sPEEK durant l'étape de mise en œuvre et d'augmenter sa conductivité au cours d'un vieillissement ex-situ (H2O2). En présence de fonctions tétrasulfures, la membrane sPEEK ne se dégrade pas durant un test de 1200h en OCV à 70°C et 100%HR.