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1
Nelp, Micah, and Micah Nelp. "Biological Synthesis and Transformation of Nitriles." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621560.
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Nitrile-containing natural products are rare in Nature, and there have been very few studies on the mechanisms by which they are synthesized and utilized. The biosynthesis of 7-deazapurine containing natural products is a unique case whereby both formation of a nitrile and its conversion to an amide are documented. The overall theme of this work is to interrogate the biosynthesis of the nitrile intermediate in the pathway and its subsequent hydration to an amide. The biosynthesis 7-cyano-7-deazaguanine (preQ₀), the key intermediate in the biosynthesis of the hypermodified base queuosine and the toyocamycin natural product, is accomplished by preQ₀ synthetase through a series of unprecedented reactions whereby the carboxylate moiety of the substrate, 7-carboxy-7-deazaguanine (CDG), is successively activated by adenylation, reacted with ammonia, and dehydrated to produce the nitrile. This one-enzyme synthesis of a nitrile is unique as the only other known route to nitriles proceeds through at least two enzymes. Nitrile hydratases are metalloenzymes that selectively hydrate nitriles to the amide and are used industrially to produce acrylamide and nicotinamide. These enzymes use a trivalent iron or cobalt complex comprised of two backbone amidate ligands and three cysteine thiolate ligands of which two are modified to the sulfenato and sulfinato form. This work describes aspects of a particular nitrile hydratase, toyocamycin nitrile hydratase (TNH). Whereas most nitrile hydratases are heterodimeric, TNH is heterotrimeric, and yet what was discovered is that only the subunit containing the active site metal complex is required for activity. This single subunit analog of the protein was used for single turnover assays in ¹⁸O-labeled water to show with high resolution mass spectrometry that the source of the product amide oxygen is actually the enzyme itself and likely the sulfenato ligand oxygen acting as a nucleophile. The mechanism of the active site complex synthesis is described showing that this is self-catalytic in the presence of cobalt(II) and molecular oxygen.
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Fleming, Fraser Fergusson. "A new synthesis of unsaturated nitriles : total synthesis of stephalic acid." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30578.
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This thesis describes the total synthesis of (±)-stephalic acid (96), the development of methodology for the conversion of ketones into α,β-unsaturated nitriles and exploratory studies aimed at developing a synthetic approach to cis-clerodane diterpenoids. In the total synthesis of (±)-stephalic acid (96), the ketone 94 (previously synthesized from 3-methyl-2-cyclohexen-1-one (105)) was converted into the enol trifluoromethanesulfonate (triflate) 108. The enol triflate 108 was coupled with lithium cyanide in the presence of a Pd(0) catalyst to provide the α,β-unsaturated nitrile 102. The latter substance was transformed into the α,β-unsaturated aldehyde 104, which was stereoselectively converted into the enol silyl ether 111. A novel triisobutylaluminum-promoted Claisen rearrangement-reduction process converted the enol allyl ether 103, obtained from the enol silyl ether 111, into the diene alcohol 118. The diene alcohol 118 was transformed via a series of reactions into (±)-stephalic acid (96).
Conversion of the ketone 94 into the α,β-unsaturated nitrile 102 required the development of new methodology for the conversion of ketones into the corresponding α,β-unsaturated nitrites. Reaction of the enol triflates 158 and 162-167 with lithium
cyanide in benzene (room temperature) in the presence of catalytic amounts of 12-crown-4 and tetrakistriphenylphosphinepalladium(0) provided the α,β-unsaturated nitriles 168 and
170-175, respectively.
Conversion of the ketone 92 (previously synthesized from 2-methyl-2-cyclohexen-1-one (191)) into the enol silyl ether 204 was accomplished via an eight step sequence. Several features of this sequence should prove useful in the development of synthetic routes to the cw-clerodane family of diterpenoids. [diagrams omitted]Science, Faculty of
Chemistry, Department of
Graduate
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Gao, Sirong. "Applications of beta-enaminonitriles : synthesis of 1,5,6-trisubstituted cytosines; synthetic approaches to (-)-swainsonine." View abstract/electronic edition; access limited to Brown University users, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3318319.
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Clutterbuck, Lisa. "The catalytic, asymmetric synthesis of cyanohydrins and amino nitriles." Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505844.
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Betke, Tobias [Verfasser]. "Chemoenzymatic synthesis of nitriles and lubricant esters / Tobias Betke." Bielefeld : Universitätsbibliothek Bielefeld, 2019. http://d-nb.info/1196638330/34.
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Skilbeck, Melanie C. "Synthesis of substituted nitriles and indoxyls using organometallic reagents." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/4652/.
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McClurg, Ryan W. "Synthesis of 2-amino-3-cyano-4H-chromenes." CardinalScholar 1.0, 2010. http://liblink.bsu.edu/uhtbin/catkey/1569021.
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The Knoevenagel reaction is defined by the condensation of an aldehyde or ketone with a carbon nucleophile produced by the deprotonation of a methylene species whose acidity is dramatically increased by bonds to strongly electron withdrawing groups. Previously, our group developed an effective one-pot method for the preparation of 4H-chromenes using sodium borohydride reduction of the cyclized intermediates formed by the Knoevenagel condensation of malononitrile with salicylaldehydes in aqueous ethanol. In this study we outline the extension of these strategies to include 2’-hydoxyphenylketones as the starting material. Many of these compounds are also unique and were prepared by Friedel-Crafts acylation of phenols with acyl chlorides and/or Fries Rearrangement of the corresponding phenyl ester. The objective of this project has been to expand the application of the methods optimized in our lab for the simple and efficient formation of carbon-carbon bonds via the selective reduction of the alkylidene portion of the Knoevenagel reaction products. These methods have allowed for the production of several important classes of natural product-like compounds. Specifically, in this investigation, we have adapted these methods to the production of various 4-alkyl and 4-aryl substituted 3-amino-2-cyano-4H-chromenes. These types of molecules exhibit diverse pharmacological activity and have been shown to be potentially useful for the treatment of various diseases. A subset of the synthesized compounds will be submitted to Eli Lilly through their PD2 program. Further variation of substrates included the reaction of salicylaldehydes with ethyl cyanoacetate or cyanoacetamide which provided products unreported in the literature. Reactions with cyanoacetates gave the expected 3-carboethoxy(ester) functionalized 4H-chromene compounds. Products from cyanoacetamide were found to occur in open rather than cyclized forms.Introduction and background literature -- Synthesis of 2'-hydroxyphenylketones -- Synthesis of 2-amino-3-cyano-4H-chromenes -- One pot method applied to salicylaldehydes with ethylcyanoacetate or cyanoacetamide.
Department of Chemistry
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Tayyari, Fariba. "Efficient one-pot reductive alkylations of malononitrile with aromatic aldehydes and one-pot synthesis of new 2-amino-3-cyano-4H-chromenes." Virtual Press, 2008. http://liblink.bsu.edu/uhtbin/catkey/1399195.
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A powerful new one-pot method has been developed for the reductive alkylation of malononitrile with aromatic aldehydes. This new procedure has vastly improved the yield and efficiency and increased the scope for the aromatic aldehydes. Incorporating water as the catalyst in ethanol for the condensation step allows stoichiometric amounts of malononitrile and aldehyde to be employed. After dilution and cooling the reduction step takes place quickly and efficiently with sodium borohydride to give monosubstituted malononitriles.The product from the reductive alkylation of malononitrile with 2-quinolinecarboxaldehyde quickly rearranges to a novel indolizine on silica gel or with heat, while alkylation of the monosubstituted derivative provides an unsymmetrically disubstituted malononitrile.We have also investigated this improved one-pot reductive alkylation using various 2-hydroxybenzaldehydes where intramolecular cyclization occurs following the condensation step and various 2-amino-3-cyano-4H-chromenes are formed.Department of Chemistry
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Yonekawa, Sayuri. "The synthesis and study of an amine functionalized crown ether." Virtual Press, 2004. http://liblink.bsu.edu/uhtbin/catkey/1295147.
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This study has resulted in a route to the first known NHZ functionalized xylenebased crown ether, 5-amino-2-methoxy-1,3-xylyl-18-crown-5. The route involves preparing 5-azido-2-methoxy-1,3-xylyl-18-crown-5 from 5-bromo-2-methoxy-1,3-xylyl18-crown-5 by reacting it in turn with n-BuLi and tosyl azide. 5-Amino-2-methoxy-1,3xylyl-l8-crown-5 was obtained by reducing 5-azido-2-methoxy-1,3-xylyl-l8-crown-5 with aqueous sodium borohydride in the presence of a phase transfer agent. The 'H NMR spectrum of the amino derivative showed NMR signals at 6 3.4-3.7 (crown CHZ), S 4.0 (benzylic), S 4.47 (methoxy), and 6 6.58 (aromatic) ppm. The integrated areas were consistent with the formula, and they also suggested the NH2 protons were in the crown CH2 area. The IR (KBr pellet) spectrum showed bands at 3408 cm' and 3364 cm' corresponding to the N-H asymmetric and symmetric stretches, respectively. This study has also provided a new procedure for the preparation of 4-bromo-2,6-bis(bromomethyl) anisole, which was the intermediate for 5-bromo-2-methoxy-1,3-xylyl-18-crown-5. It involved reacting 4-bromophenol in turn with 30 % formaldehyde, dimethylsulfate, and HBr in acetic acid.Department of Chemistry
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Tan, Jennie. "Synthesis and Characterization of Complexes of [Rh2(NPhCOCH3)4] and Nitriles." Digital Commons @ East Tennessee State University, 2012. https://dc.etsu.edu/honors/49.
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The rhodium carboxamide [Rh2(NPhCOCH3)4]L (L=axial ligand), has applications as a catalyst for carbenoid transformations. To explore the nature of the rhodium-carbene bond, studies between Rh2(NPhCOCH3)4 and nitriles were proposed. Trials of the benzonitrile, o-tolunitrile, and m-tolunitrile have been performed and characterized on the 2,2-trans [Rh2(NPhCOCH3)4] complex via NMR spectroscopy, IR spectroscopy, and X-ray crystallography.
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Oike, Keiko [Verfasser]. "Synthesis of α-keto acids and nitriles by enzyme catalysis / Keiko Oike." Bielefeld : Universitätsbibliothek Bielefeld, 2021. http://d-nb.info/1237048605/34.
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Del, Vecchio Franklin A. "An investigation into the asymmetric synthesis of imidazolinones via reaction of chiral a-amino acid esters with nitriles /." Online version of thesis, 1991. http://hdl.handle.net/1850/11069.
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Murai, Masahito. "Synthesis of Heterocycles Based on Transition Metal-catalyzed Cycloisomerization Reactions of Nitriles Having Multifunctionalities." 京都大学 (Kyoto University), 2010. http://hdl.handle.net/2433/120880.
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Caillé, Julien. "Réactivité d’organométalliques sur des nitriles fonctionnalisés : réactions de cyclopropanation asymétrique et double addition." Thesis, Le Mans, 2017. http://www.theses.fr/2017LEMA1028.
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Les cyclopropanes sont des motifs structuraux importants en chimie médicinale. Parmi les synthèses existantes du fragment aminocyclopropane, les réactions dérivées de la réaction de Kulinkovich, appliquées aux amides et aux nitriles, sont des méthodes simples d'accès. Cependant, il n'existe pas de version asymétrique efficace. Dans une première partie, l'étude de l'utilisation de complexes de titane optiquement actifs pour la préparation de spirolactames chiraux à partir de cyanoesters a été réalisée. Ce travail a permis de mettre au point une méthode d'évaluation rapide de ligands chiraux dont leur criblage a montré que les composés de la famille du Taddol fournissent les meilleurs excès énantiomériques. L'énantiosélectivité demeure cependant actuellement trop faible pour présenter un intérêt en synthèse. Dans une seconde partie, la synthèses de carbinamines tertiaires, un autre motif important, a été étudié à partir d'acylcyanhydrines et d'organométalliques. En particulier, la synthèse d'une bibliothèque d'acides aminés quaternaires a été entreprise à partir d'hydroxyamides. L'incorporation de deux organométalliques différents sur des acylcyanhydrines a été également effectuée conduisant à l'obtention d'hydroxyamides chiraux sous forme racémique. Enfin, l'emploi de réactifs organozinciques allyliques nous a permis d'accéder à de très bons rendements en produits de double addition. Ces hydroxyamides ont été ensuite valorisés comme précurseurs de plateformes multifonctionnelles pour la ligation chimiqueCyclopropylamines are important scaffolds in medicinal chemistry. Among the syntheses of the aminocyclopropane moiety, the Kulinkovich-related reactions applied to amides and nitriles furnish straightforward access. However, no efficient asymmetric version has been published to date. In a first part, the study of optically active titanium complexes for the preparation of chiral spirolactams from cyanoesters has been undertaken. This work allowed us to setup a quick evaluation method for chiral ligands whose screening revealed that Taddol and its derivatives lead to the best enantiomeric excesses. However, the enantioselectivity remains too low for synthetic purposes. In a second part, the synthesis of tertiary carbinamines, another important scaffold, has been studied from acylcyanohydrins and organometallics. Notably, the synthesis of a quaternary aminoacids library was achieved. The incorporation of two different organometallics on acylcyanohydrins was also undertaken, leading to the preparation of chiral hydroxyamides in a racemic fashion. Lastly, very good yields in double addition products were obtained by using allylic organozinc reagents. The obtained hydroxyamides were used as precursors of polyfunctional linkers for the chemical ligation
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Wardell, Jacklyn Anne. "Studies on the synthesis of heterocyles by reaction of lithiated #beta#-methyl and #beta#-amino-azines with nitriles." Thesis, University of Salford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315454.
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Orozco, Erika Vanessa Meñaca. "Síntese e relações estrutura-atividade de dipeptidil-nitrilas inibidoras da cruzaína." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/75/75133/tde-06052015-141806/.
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A cruzaína é a principal cisteíno protease encontrada no parasito Trypanosoma cruzi, o agente etiológico da Doença de Chagas. A enzima é essencial para o desenvolvimento e sobrevivência do parasito dentro do hospedeiro e possui uma excelente validação pré-clínica como alvo susceptível à ação de fármacos. Várias classes de inibidores peptídicos reversíveis e irreversíveis, baseados no estado de transição, inibem efetivamente a cruzaína. No entanto, a maioria destes inibidores ainda não apresenta perfis farmacodinâmicos/farmacocinéticos adequados e/ou estão relacionados com potenciais efeitos fora do alvo (do inglês, off-target). Com o objetivo de encontrar inibidores mais eficientes e seletivos, foi aplicado uma abordagem de planejamento de ligantes baseada em hipótese, combinando quiminformática, síntese orgânica, ensaios bioquímicos e determinação do modo de interação para validar os compostos planejados como inibidores de cruzaína. Neste trabalho, é mostrado um conjunto de dipeptidil-nitrilas que foram sintetizadas e avaliadas com base nestes métodos para investigar as interações nos subsítios S1, S2 e S3 de cruzaína. Nossos resultados demonstram o sucesso da abordagem aplicada que resultou na identificação de vários inibidores da cruzaína em concentrações que chegam a sub-micromolar. Alguns dos compostos dessa classe de dipeptidil-nitrilas também são agentes tripanossomicidas por apresentar concentrações efetivas com formas infectivas do T. cruzi em baixo micromolar.Cruzain is the major cysteine protease found in the parasite Trypanosoma cruzi, the etiologic agent of Chagas disease. The enzyme is essential for the development and survival of the parasite within host cells, having excellent pre-clinical validation evidence as a druggable target. Several classes of peptide inhibitors including transition state-based reversible and irreversible ones effectively inhibit cruzain. However, most of these inhibitors still have poor PK/PD profiles and are related with potential off target effects. In order to find more efficient and selective inhibitors, we have applied the hypothesis driven ligand design approach, combining cheminformatics, organic synthesis, biochemical assays and mode of binding determination to validate the designed compounds as cruzain inhibitors. Here, we show a set of dipeptidyl nitriles that were synthetized and evaluated based on these methods to probe interactions at S1, S2 and S3 pockets of cruzain binding site. Our results unveil the success of the applied approach that yielded in the identification of several cruzain inhibitors at sub-micromolar concentrations. Some of the compounds of this class of dipeptidyl nitriles are also trypanocidal agents with effective concentrations in the low micromolar range against infective forms of T. cruzi.
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Quarshie, Fredricka F. "Synthesis and Characterization of 2,2-cis-[Rh2(NPhCOCH3)4]•NCC6H4R where R = H, 2-CH3, 3-CH3, 4-CH3 and [Rh2(O2CCH3)(NPhCOCF3)3]." Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etd/2289.
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Five novel compounds were synthesized and characterized. Crystal structures were determined using Rigaku Mercury 375/MCCD(XtaLAB mini) diffractometer with graphite monochromated MoKα radiation. The crystal structures of [Rh2(NPhCOCH3)4•xNCC6H4R where x = 1 or 2 and R=H, 2-CH3,3-CH3 and 4-CH3 were solved to an R1 value of less than 5 (R1= Σ||Fo| - |Fc|| / Σ |Fo|). In each of the nitrile complexes, the rhodium is five or six coordinate and possesses pseudo D4h symmetry. The complexes were also characterized by NMR and IR spectroscopy. [Rh2(CO2CCH3)(PhCOCF3)3] was also synthesized. In this complex, each rhodium atom is six coordinate, thus each rhodium is in an octahedral environment. Details of each synthesized complex are discussed.
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FERRAZ, CAROLINE C. "Desenvolvimento de uma membrana nanoestruturada à base de poliacrilamida para veiculação de proteínas." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10539.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Charles, Mark David. "Synthetic studies toward a total synthesis of morphine." Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272077.
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Cordes, Niklas [Verfasser], and Wolfgang [Akademischer Betreuer] Schnick. "Ammonothermal synthesis of functional nitride oxides and ternary nitrides / Niklas Cordes ; Betreuer: Wolfgang Schnick." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2019. http://d-nb.info/1192215508/34.
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Bem, David S. (David Stanley). "Synthesis of new ternary nitrides." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11902.
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Shah, Syed Imran Ullah. "Synthesis of transition metal nitrides and silicon based ternary nitrides." Thesis, University of Southampton, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.580538.
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Solution phase ammonolysis and sol-gel techniques that produce polymeric metal-amide precursors are of growing interest in the synthesis of nitride materials, which result from the thermal decomposition of the polymer. They can be used to control composition and to produce a large number of useful morphologies such as nanoparticles, films, monoliths, aerogels, and materials with large surface area such as foams. The synthesis of nitride materials using ammonolysis of metal amides and chlorides has so far largely focused on producing powders for applications such as catalysis, or thin films by chemical vapour deposition and related techniques. In this thesis, formation of tantalum and molybdenum nitride nanoparticles and metal-silicon nitride based nanocomposites have been synthesised using non-oxide precursors by solution phase ammonolysis and sol-gel methods respectively. For tantalum nitride nanoparticles Ta(NMe2)5 in THF was ammonolysed with ammonia at - 78 QC and the polymeric precursor was pyrolysed at various temperatures under ammonia. Amorphous TaN was obtained at 700 QC and below, while Ta3Ns was obtained at 800 QC under ammonia and also by re-annealing the amorphous samples at 800 QC under nitrogen. Molybdenum nitride powders were obtained by solution phase ammonolysis of MoCl, or Mo(NMe2)4 and further annealing the polymeric precursors on different temperatures. The chloride precursor resulted in hexagonal Mo'N, at 500 QC, or rock salt Mobl, at 700-1000 QC and mixture of both at 600 QC. The amide precursor resulted phase pure hexagonal MoNx at 600 QC and rock salt mixed with hexagonal at 1000 QC. Samples produced at 600 QC consisted mainly of nanotubes. Some decomposition to molybdenum metal was found in MoN obtained at 1000 QC from either precursor source. Co-ammonolysis of Ta(NMe2)5 or Mo(NMe2)4 with Si(NHMe)4 was carried out using sol-gel technique. Polymeric metal-silicon amide precursors were annealed at 600 or 1000 QC. The Ta/Si precursor produced amorphous nanocomposites and no phase segregation was observed even after high temperature annealing. With molybdenum the products were nanocomposites of molybdenum nitride particles, including nanotubes, supported on a silicon nitride amorphous matrix.
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Azeez, Qaisar A. "Synthesis of ultrafine aluminum nitride powders in a flow reactor." Ohio : Ohio University, 1988. http://www.ohiolink.edu/etd/view.cgi?ohiou1182779122.
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Castro, Darren T. (Darren Thomas) 1970. "Synthesis, processing, and properties of nanocrystalline nitrides." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10227.
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Brandt, Martin William. "Synthesis and polymerizations of nitrile substituted quinodimethanes." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184341.
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The spontaneous polymerization behavior of an acceptor substituted quinodimethane was investigated. High molecular weight homopolymers of 7,8,-di(ethoxycarbonyl)-7,8-dicyanoquinodimethane (DEDCQ) or copolymers of DEDCQ-styrene (St) and DEDCQ-p-methoxystyrene (p-MeOSt) were formed spontaneously in chloroform containing acetic acid. All polymerizations occurred by a radical mechanism. High molecular weight polymers formed at low conversion. Radical homopolymerization of DEDCQ was promoted by ambient light or heat. DEDCQ-p-MeOSt copolymerizations yielded alternating copolymers, which formed rapidly relative to the DEDCQ homopolymers and copolymers (rich in styrene). All of these polymerizations are thought to begin with a bond forming mechanism and propagate by polyaddition. A new acceptor group substituted quinodimethane was synthesized, characterized and copolymerized with electron donating monomers. Oxidation of the dianion of α, α'-dicyano-α, α'-diphenyl-p-xylene yielded 45% 7,8-dicyano-7,8-diphenylquinodimethane. In solution this compound exists in both the trans and cis forms but forms a sharply melting crystalline solid. It was resistant to homopolymerization but did form low molecular weight copolymers with electron rich aromatic monomers.
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York, David C. "Synthesis of azaacridines using nitrene intermediates." Thesis, Keele University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254883.
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Buha, Jelena. "Nonaqueous syntheses of metal oxide and metal nitride nanoparticles." Phd thesis, Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2008/1836/.
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Nanostructured materials are materials consisting of nanoparticulate building blocks on the scale of nanometers (i.e. 10-9 m). Composition, crystallinity and morphology can enhance or even induce new properties of the materials, which are desirable for todays and future technological applications. In this work, we have shown new strategies to synthesise metal oxide and metal nitride nanomaterials.
The first part of the work deals with the study of nonaqueous synthesis of metal oxide nanoparticles. We succeeded in the synthesis of In2O3 nanopartcles where we could clearly influence the morphology by varying the type of the precursors and the solvents; of ZnO mesocrystals by using acetonitrile as a solvent; of transition metal oxides (Nb2O5, Ta2O5 and HfO2) that are particularly hard to obtain on the nanoscale and other technologically important materials.
Solvothermal synthesis however is not restricted to formation of oxide materials only. In the second part we show examples of nonaqueous, solvothermal reactions of metal nitrides, but the main focus lies on the investigation of the influence of different morphologies of metal oxide precursors on the formation of the metal nitride nanoparticles. In spite of various reports, the number and variety of nanocrystalline metal nitrides is marginally small by comparison to metal oxides; hence preformed metal oxides as precursors for the preparation of metal nitrides are a logical choice. By reacting oxide nanoparticles with cyanamide, urea or melamine, at temperatures of 800 to 900 °C under nitrogen flow metal nitrides could be obtained. We studied in detail the influence of the starting material and realized that size, crystallinity, type of nitrogen source and temperature play the most important role. We have managed to propose and verify a dissolution-recrystallisation model as the formation mechanism. Furthermore we could show that the initial morphology of the oxides could be retained when ammonia flow was used instead.Nanostrukturierte Materialien sind Materialien, die aus nanopartikulären Baueinheiten in der Größenordnung von Nanonmetern (d.h. 10-9 m) bestehen. Zusammensetzung, Kristallinität und Morphologie können die natürlichen Eigenschaften dieser Materialien verbessern oder zusätzliche Eigenschaften erzeugen, die für heutige und zukünftige Anwendungen und Verfahren wünschenswert sind. In dieser Arbeit präsentieren wir neue Strategien zur Synthese von Nanopartikeln der Metaloxide und Metalnitride. Im einführenden Teil wird die nichtwässrige Synthese von Metaloxidnanopartikeln beschrieben. Uns gelang die Darstellung von In2O3 Nanopartikeln, deren Größe und Form wir durch die Wahl des Prekursors und des Lösemittels deutlich beeinflussen konnten; von ZnO Mesokristallen durch den Einsatz von Acetonitril als Lösemittel; von Übergangsmetalloxiden (Nb2O5, Ta2O5 and HfO2), die besonders schwer im Nanomaßstab zu erhalten sind und von anderen, technisch relevanten Materialien. Die Möglichkeiten der solvothermalen Synthese sind nicht mit der Darstellung von Oxidmaterialen erschöpft. Im zweiten Teil zeigen wir einige Beispiele nichtwässriger, solvothermaler Synthese von Metalnitriden auf; das Hauptaugenmerk liegt aber auf einer Betrachtung der Einflüsse der Morphologie von Metaloxidnanopartikelprekursoren auf die Bildung der Metalnitridnanopartikel. Die Anzahl und Vielfalt bekannter nanokristalliner Metalnitride ist verschwindend klein im Vergleich zu den Metaloxiden, die in der Fachliteratur etabliert sind und demzufolge einen reichen Baukasten an Prekursoren zur Darstellung von Metalnitriden liefern. Durch die Reaktion von Metaloxidnanopartikeln mit Cyanamid, Urea oder Melamine bei Temperaturen von 800 bis 900 °C unter Stickstofffluss konnten Metalnitride erhalten werden. Eine detaillierte Studie der Reaktionsbedingungen und des Reaktionsablaufs zeigte auf, dass Größe und Kristallinität der Metaloxide, die Art der Stickstoffquelle und die Temperatur die entscheidenden Faktoren sind und legte eine Auflösungs-Rekristallisation als Modelmechanismus dieser Art Reaktion nahe. Darüber hinaus konnte gezeigt worden, dass die anfängliche Morphologie des Oxids unter einem Ammoniafluss beibehalten werden konnte.
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Ivol, Flavien. "Formulation d'électrolytes sécuritaires pour supercondensateurs." Thesis, Tours, 2019. http://www.theses.fr/2019TOUR4020.
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L’objectif de cette thèse est de développer et d’optimiser un électrolyte organique performant et sécuritaire pour des supercondensateurs capacitifs. En effet, l’électrolyte aujourd’hui utilisé dans ces systèmes, présente des risques d’inflammabilité importants. Dans le cadre de cette thèse plusieurs solvants nitriles et dinitriles ont été utilisés pour la formulation d’électrolytes alternatifs pour les supercondensateurs. Ces solvants sont choisis pour leur grande stabilité thermique et faible volatilité. Par ailleurs, il a été proposé de remplacer le sel d’électrolyte de référence par des liquides ioniques aprotiques commerciaux ou issus de synthèses en laboratoire. En effet, la forte miscibilité et compatibilité des liquides ioniques avec les solvants choisis permet la formulation d’électrolyte fortement concentrés en ions favorisant ainsi le processus de stockage à la double-couche électrochimique. En outre, ces nouvelles formulations présentent un domaine liquide bien plus étendu que les formulations utilisant le sel de référence. Plus important encore, les travaux exposés dans ce manuscrit présentent une démarche expérimentale multiparamétrique s’appuyant parfois sur des modèles mathématiques et prédictifs pour aboutir à des formulations d’électrolytes optimiséesThe main objective of this PhD thesis is to design and optimize an efficient and safe organic electrolyte for capacitive supercapacitor applications. The benchmark electrolyte currently used in these particular systems presents a significant safety drawback, due to its high flammability. To overcome this issue, several nitrile and dinitrile solvents have been used to formulate alternative electrolytes for supercapacitors. These solvents were initially identified based on their relatively high thermal stability and low volatility. Furthermore, it was also proposed to substitute the reference molten salt with commercially available aprotic ionic liquids, or ones synthetized in the laboratory. The substitution was found to enhance the salt miscibility and compatibility when combined with selected organic solvents, allowing for the formulation of highly concentrated electrolytes with improved electric double-layer storage process. In addition, the ionic liquid-based electrolytes have a larger liquidus temperature range than that of the benchmark molten salt. More importantly, this work presents a clear strategy led by a multi-parametric experimental approach supported by theoretical calculations to optimize the formulation of safer electrolytes for supercapacitors
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Chirico, Pietro. "Synthesis of nanocrystalline nitride materials." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/193141/.
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Davies, Christopher Daniel. "Asymmetric synthesis utilising chiral vinyl dioxazaborocines." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322323.
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Oldham, Sophie E. "Synthesis and characterisation of intermetallic nitrides and germanides." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.497063.
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Sviridov, Lev A. "Synthesis and Characterization of New Transition - Metal Nitrides." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526120.
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Baker, Charles Fielding. "Synthesis and structural studies of low dimensional nitrides." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368271.
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Bailey, Andrew Steven. "Synthesis and characterisation of layered and defect nitrides." Thesis, University of Nottingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435363.
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Montoya, Anthony Tristan. "Synthesis of carbon nitrides and composite photocatalyst materials." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6479.
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This thesis describes the synthesis, characterization and photocatalytic applications of carbon nitride (C3N4) and titanium dioxide (TiO2) materials. C3N4 was prepared from the thermal decomposition of a trichloromelamine (TCM) precursor. Several different reactor designs and decomposition temperatures were used to produce chemically and thermally stable orange powders. These methods included a low temperature glass Schlenk reactor, a high mass scale stainless steel reactor, and decomposition at higher temperatures by the immersion of a Schlenk tube into a furnace. These products share many of the same structural and chemical properties when produced by these different methods compared to products from more common alternate precursors in the literature, determined by infrared spectroscopy (IR), nuclear magnetic resonance spectroscopy (NMR), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and elemental analysis. C3N4 is capable of utilizing light for photocatalysis due to its moderate band gap (Eg), measured to be between 2.2 and 2.5 eV. This enables C3N4 to be used in the photocatalytic degradation of organic dyes and the production of hydrogen via the water-splitting reaction. C3N4 degraded methylene blue dye to less than 10% of its initial concentration in less than an hour of UV light illumination and 60% under filtered visible light in 150 minutes. It also degraded methyl orange dye to below 20% in 70 minutes under UV light and below 60% in 150 minutes under visible light. Using precious metal co-catalysts (Pt, Pd, and Ag) photo-reduced onto the surface of C3N4, hydrogen was produced from a 10% aqueous solution of triethanolamine at rates as high as 260 μmol h-1 g-1.
C3N4 was also modified by mixing the precursor with different salts (NaCl, KBr, KI, KSCN, and NH4SCN) as hard templates. Many of these salts reacted with TCM by exchanging the anion with the chlorine in TCM. The products were mostly prepared using the high temperature Schlenk tube reactor, and resulted in yellow, orange, or tan-brown products with Eg values between 2.2 and 2.7 eV. Each of these products had subtle differences in the IR spectra and elemental composition. The morphology of these C3N4 products appeared to be more porous than unmodified C3N4, and the surface area for some increased by a factor of 4. These products demonstrated increased activity for photocatalytic hydrogen evolution, with the product from TCM-KI reaching a peak rate as high as 1,300 µmol h-1 g-1. C3N4 was coated onto metal oxide supports (SiO2, Al2O3, TiO2, and WO3) with the goal of utilizing enhanced surface area of the support or synergy between two different semiconductors. These products typically required higher temperature synthesis conditions in order to fully form. The compositions of the SiO2 and Al2O3 products were richer in nitrogen and hydrogen compared to unmodified C3N4. The higher temperature reactions with C3N4 and WO3 resulted in the formation of the HxWO3 phase, and an alternate approach of coating WO3 on C3N4 was used. The degradation of methyl orange showed a significant increase in adsorption of dye for the composites with SiO2 and Al2O3, which was not seen with any of the individual components. The composite between C3N4 and TiO2 showed improved activity for hydrogen evolution compared to unmodified C3N4.
The surface of TiO2 was modified by the reductive photodeposition of several first row transition metals (Mn, Fe, Co, Ni, and Cu). This process resulted in the slight color change of the white powder to shades of light yellow, blue or grey. Bulk elemental analysis showed that these products contained between 0.04-0.6 at% of the added metal, which was lower than the targeted deposit amount. The Cu modified TiO2 had the largest enhancement of photocatalytic hydrogen evolution activity with a rate of 8,500 µmol h-1 g-1, a factor of 17 higher than unmodified TiO2.
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Shearer, Jason Michael. "Synthetic models for metalloenzymes containing sulfur-metal bonds /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8681.
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Kraupner, Alexander. "Neuartige Synthese magnetischer Nanostrukturen: Metallcarbide und Metallnitride der Übergangsmetalle Fe/Co/Ni." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5231/.
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Magnetische Nanopartikel bieten ein großes Potential, da sie einerseits die Eigenschaften ihrer Bulk-Materialien besitzen und anderseits, auf Grund ihrer Größe, über komplett unterschiedliche magnetische Eigenschaften verfügen können; Superparamagnetismus ist eine dieser Eigenschaften. Die meisten etablierten Anwendungen magnetischer Nanopartikel basieren heutzutage auf Eisenoxiden. Diese bieten gute magnetische Eigenschaften, sind chemisch relativ stabil, ungiftig und lassen sich auf vielen Synthesewegen relativ einfach herstellen. Die magnetischen Eigenschaften der Eisenoxide sind materialabhängig aber begrenzt, weshalb nach anderen Verbindungen mit besseren Eigenschaften gesucht werden muss. Eisencarbid (Fe3C) kann eine dieser Verbindungen sein. Dieses besitzt vergleichbare positive Eigenschaften wie Eisenoxid, jedoch viel bessere magnetische Eigenschaften, speziell eine höhere Sättigungsmagnetisierung.
Bis jetzt wurde Fe3C hauptsächlich in Gasphasenabscheidungsprozessen synthetisiert oder als Nebenprodukt bei der Synthese von Kohlenstoffstrukturen gefunden. Eine Methode, mit der gezielt Fe3C-Nanopartikel und andere Metallcarbide synthetisiert werden können, ist die „Harnstoff-Glas-Route“. Neben den Metallcarbiden können mit dieser Methode auch die entsprechenden Metallnitride synthetisiert werden, was die breite Anwendbarkeit der Methode unterstreicht.
Die „Harnstoff-Glas-Route“ ist eine Kombination eines Sol-Gel-Prozesses mit einer anschließenden carbothermalen Reduktion/Nitridierung bei höheren Temperaturen. Sie bietet den Vorteil einer einfachen und schnellen Synthese verschiedener Metallcarbide/nitride.
Der Schwerpunkt in dieser Arbeit lag auf der Synthese von Eisencarbiden/nitriden, aber auch Nickel und Kobalt wurden betrachtet. Durch die Variation der Syntheseparameter konnten verschiedene Eisencarbid/nitrid Nanostrukturen synthetisiert werden. Fe3C-Nanopartikel im Größenbereich von d = 5 – 10 nm konnten, durch die Verwendung von Eisenchlorid, hergestellt werden. Die Nanopartikel weisen durch ihre geringe Größe superparamagnetische Eigenschaften auf und besitzen, im Vergleich zu Eisenoxid Nanopartikeln im gleichen Größenbereich, eine höhere Sättigungsmagnetisierung. Diese konnten in fortführenden Experimenten erfolgreich in ionischen Flüssigkeiten und durch ein Polymer-Coating, im wässrigen Medium, dispergiert werden. Desweiteren wurde durch ein Templatieren mit kolloidalem Silika eine mesoporöse Fe3C-Nanostruktur hergestellt. Diese konnte erfolgreich in der katalytischen Spaltung von Ammoniak getestet werden.
Mit der Verwendung von Eisenacetylacetonat konnten neben Fe3C-Nanopartikeln, nur durch Variation der Reaktionsparameter, auch Fe7C3- und Fe3N-Nanopartikel synthetisiert werden. Speziell für die Fe3C-Nanopartikel konnte die Sättigungsmagnetisierung, im Vergleich zu den mit Eisenchlorid synthetisierten Nanopartikeln, nochmals erhöht werden.
Versuche mit Nickelacetat führten zu Nickelnitrid (Ni3N) Nanokristallen. Eine zusätzliche metallische Nickelphase führte zu einer Selbstorganisation der Partikel in Scheiben-ähnliche Überstrukturen.
Mittels Kobaltacetat konnten, in Sphären aggregierte, metallische Kobalt Nanopartikel synthetisiert werden. Kobaltcarbid/nitrid war mit den gegebenen Syntheseparametern nicht zugänglich.Magnetic nanoparticles offer a great potential, because they exhibit on the one hand the properties of their bulk materials and on the other hand, because of their size, completely different magnetic properties. The most established applications of magnetic nanoparticles are based on iron oxide. These oxides have good magnetic properties, they are chemical relatively stable, non toxic and easy to prepare. But the magnetic properties are limited. Therefore, we need new materials with improved magnetic properties. Iron carbide (Fe3C) could be one of these materials. Up to now, Fe3C was mainly synthesized in chemical vapor deposition processes (CVD) or was found as side product in the synthesis of carbon structures. A method for the systematical synthesis of metal carbides is the “Urea-Glass-Route”. In addition to the synthesis of metal carbides, this method allows to synthesize metal nitrides, which shows the broad practicability. The “Urea-Glass-Route” is a combination of a sol-gel process with following carbothermal reduction/nitridation at higher temperatures. The method is fast and simple and it is possible to synthesis different metal carbides/nitrides. The main topic of this work is the synthesis of iron carbide/nitride, but also cobalt and nickel is examined. By varying the synthesis parameters, different iron carbide/nitride nanostructures could be synthesized. With the use of iron chloride, Fe3C nanoparticles, in the size range of d = 5 – 10 nm, could be produced. Because of their small size, the particles show superparamagnetism and compared to iron oxide particles (in the same size range) a higher saturation magnetization. In following experiments, the particles could be successfully dispersed in an ionic liquid and with a polymer coating in aqueous medium. Furthermore, via templating with colloidal silica a mesoporous Fe3C structure could be synthesized. The material could be successfully tested in the catalytic ammonia decomposition. By changing the iron source to iron acetylacetonate, Fe7C3 and Fe3N nanoparticles, in addition to Fe3C, could be also synthesized. With nickel acetate it was possible to synthesize nickel nitride (Ni3N) nano crystals. An additional metallic nickel phase in the sample leads to a self organization to disk-like superlattice. Via cobalt acetate, in spheres aggregated, metallic cobalt nanoparticles could be synthesized. Cobalt carbide or nitride was not accessible under these synthesis parameters.
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O'Meara, Paul Martin. "The synthesis and characterisation of binary and ternary nitrides." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311740.
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Cleaves, Peter A. "Synthesis, reactivity, and electronic structure of molecular uranium nitrides." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/38057/.
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The study of metal-ligand multiple bonding offers insight into the electronic structure and bond of metal systems. Until recently, for uranium, such systems were limited to uranyl, and terminal chalcogenide, imide and carbene complexes. In 2012, this was extended to nitrides with the first preparation of a uranium–nitride (U≡N) species isolable under standard conditions, namely [U(TrenTIPS)(N)][Na(12C4)2] (52), which is prepared by the two-electron reduction of sodium azide with a trivalent uranium(III) precursor [U(TrenTIPS)] (15), and the subsequent sequestration and encapsulation of the loosely bound sodium cations. In order to then fully explore the bonding within this newly isolated fragment, alternative routes to prepare uranium–nitrides were investigated, in order to both expand the family of known uranium–nitrides, as well as remove the synthetic bottleneck that occurs due to issues in scale-up. The reduction of the pre-installed azide ligand of [U(TrenTIPS)(N3)] (13) with one-electron external reductants, namely the alkali powders or metals (lithium and sodium, rubidium and caesium) and potassium graphite, affords the dinuclear uranium(V)–nitride species of the form [{U(TrenTIPS)(µ-N)(µ-M)}2] (M = Li, Na, K, Rb, Cs; 51, 106 – 109). Analogously to the preparation of the first terminal uranium–nitride system, encapsulation of the cation affords separated ion pair species of the form [U(TrenTIPS)(N)][M(crown)2] (M = Na, K, Rb, Cs; 52, 114 – 117), or if a slightly larger co-ligand is utilised, capped uranium–nitrides of the form [U(TrenTIPS){(µ-N)(µ-M)(crown)}] (M = Li, Na, K, Rb, Cs; 53, 111 – 113, 118, 119). Oxidation of the separated ion pair nitrides affords the neutral uranium(VI)–nitride, [U(TrenTIPS)(N)] (54). Attempts to prepare dinuclear uranium–nitrides by the reduction of 13 with benzyl potassium (KCH2Ph) afforded instead the cyclometallated species [U{CH2CH(Me)Si(iPr)2NCH2CH2N(CH2CH2NSiiPr3)2}] (110). Unexpectedly, in an inversion of the anticipated reactivity trend, attempts to prepare a thorium congener of 110 did not initially form a cyclometallated species, with the reaction of [Th(TrenTIPS)(I)] (123) and KCH2Ph affording [Th(TrenTIPS)(CH2Ph)] (124); and cyclometallation was thermolytically induced. Computational calculations indicate that this is due to the stabilisation of the σ bond metathesis transition state in the uranium case. A combination of experimental and computational studies allows for the determination of the electronic structure of the families of uranium(V)–nitrides, by considering all the spectroscopic data available for the dinuclear, terminal separated ion pair and capped species in conjunction with ab initio calculations. This approach then leads to a description of the ground and excited states of Tren–uranium(V) nitrides, where [{U(TrenTIPS)(µ-N)(µ-K)}2] (107) and [U(TrenTIPS){(µ N)(µ Na)(15C5)}] (53) exhibit a jz ≈ ±5/2 ground state doublet, with a jz ≈ ±3/2 first excited state doublet, in contrast to all other nitrides studied, where the reverse is the case. The excited states can be derived from spectroscopic data (EPR and UV-vis-NIR), which corroborate these findings. A series of investigations into the small molecule activation chemistry of uranium–nitrides were instigated. The reaction of Tren–uranium(VI) or uranium(V)–nitrides (54, with carbon monoxide resulted in two-electron reductive carbonylation to afford the corresponding uranium(IV)– and uranium(III)–isocyanates, [U(TrenTIPS)(NCO)] (135), [U(TrenTIPS)(NCO)][K(Bn 15C5)2] (136), [U(TrenTIPS){(µ NCO)(µ K)(18C6)}] (137). Reduction of 135 with potassium graphite afforded complete nitrogen atom transfer to eliminate KOCN and generate 15. In the presence of crown, the uranium–nitrogen bond is retained and 136 or 137 can be isolated. A synthetic cycle for the conversion of NaN3 to NaOCN was investigated employing the UIII-UV redox couple by the reaction of 15, NaN3 and CO in pyridine, where one turnover was observed. DFT calculations were used to model these reactions, and they provided evidence for nucleophilic behaviour and explained the difference in the rates of reaction. The reaction of heteroallenes (CE2, E = O, S) with Tren–uranium nitrides was also investigated. It was found that terminal uranium–nitrides react with CO2 to afford uranium–oxo–isocyanates, with retention of uranium oxidation state. In the case of uranium(V), [U(TrenTIPS)(O)(NCO)][K(Bn-15C5)2] (138) is stable, though for uranium(VI), [U(TrenTIPS)(O)(NCO)] (139), a cyanate radical is extruded, which decomposes via diisooxocyan to afford N2 and CO, preparing [U(TrenTIPS)(O)] (122). With CS2, uranium(V)–nitrides undergo overall disproportionation to afford uranium(IV)–trithiocarbonates [U(TrenTIPS)(κ2-CS3)][K(Bn-15C5)2] (140) and [{U(TrenTIPS)(µ-κ2:κ1-CS3)(µ-K)(Bn2-18C6)}2(µ-C6H6)] (141), and uranium(VI)–nitride (54), alongside the formation of [K(crown)n][SCN]. The reaction of 54, which cannot engage in disproportionation chemistry, with CS2 prepares a uranium(IV)–isothiocyanate, [U(TrenTIPS)(NCS)] (142), by the elimination of sulfur, which can be scavenged by triphenylphosphine. Calculations reproduced experimental outcomes, and show that while uranium(V)–nitrides (115) engage in outer sphere type reactivity, uranium(VI)–nitrides (54) instead react via inner sphere mechanisms.
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Porter, Spencer H. "Perovskite and Pyrochlore Tantalum Oxide Nitrides: Synthesis and Characterization." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1332499280.
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Eberhardt, Jan Kurt. "Metallkomplexe mit Oligonitrilen Synthese und Anwendungen /." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=972279628.
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Siddons, Daniel James. "Synthetic routes to binary and ternary nitrides." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363637.
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Bekele, Challa Megenassa. "SYNTHESIS AND CHARACTERIZATION OF GaN AND ZnGeN2." Case Western Reserve University School of Graduate Studies / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1165271807.
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Jackson, Henry Lee. "Synthetic models of Fe-type nitrile hydratase /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/8532.
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Boyd, Ewan Campbell. "Synthetic applications of nitrile oxide/isoxazoline chemistry." Thesis, University of Edinburgh, 1992. http://hdl.handle.net/1842/12525.
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Three alkenes, (R/S)-2-phenyl-4-vinyl-4,5-dihydro-oxazole (11), (4R)-3-N-t-butoxycarbonyl-2,2-dimethyl-4-vinyloxazolidine (12) and (2R)-2-(N-t-butoxycarbonyl)aminobut-3-en-1-ol (13), have been prepared from (S)-serine and used in cycloaddition reactions with some common nitrile oxides, to investigate the effect of an allylic nitrogen at an α-chiral centre on π-facial selectivity. Alkene (11) was prepared in racemic form after an unexpected racemisation during its synthesis. Cycloaddition reactions with three nitrile oxides (benzonitrile oxide, ethoxycarbonylformonitrile oxide and bromonitrile oxide) furnished the isoxazoline/oxazoline adducts in poor to good yield. π-facial selectivity varied from 69.31 (BrCNO) to 82:18 (EtO_2CCNO) in favour of the (5R,4'S) erythro product. The stereoselectivity has been explained by both a steric transition state model and by the existence of a stereoelectronic contribution to the stability of the transition state. Alkene (12) afforded good yield of cycloadducts with the same three nitrile oxides, but only gave moderate π-facial selectivity (ca. 66:34); the (5R,4'S) erythro products were again favoured. The diastereomeric products were separated after partial deprotection of the β-amino-alcohol moiety (deacetonisation). The observed π-facial selectivity has been explained by a steric transition state model. The N-protected vinylamino-alcohol (13) has been reacted with benzonitrile oxide and ethoxycarbonylformonitrile oxide to give the corresponding cycloadducts in moderate yield. π-facial selectivity was poor, and the (5S,2'S) threo isomer was favoured. The reduction and reversal of π-facial induction has been explained by a hydrogen bonding interaction in the transition state. Two examples of chiral heterocyclic nitrile oxides (39) and (41) which correspond to the two heterocyclic alkenes have also been prepared, each of which represents a protected chiral β-amino-alcohol nitrile oxide.
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Baik, Youngmin. "Carbothermal synthesis of aluminum nitride using sucrose." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60643.
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In this work, the carbothermal reduction of Al$ sb2$O$ sb3$ to AlN was studied. Several kinds of aluminum oxides including $ alpha$-Al$ sb2$O$ sb3$, $ gamma$-Al$ sb2$O$ sb3$, $ theta$-Al$ sb2$O$ sb3$ and boehmite (AlOOH) were examined in order to observe the differences in reaction behaviour and powder characteristics obtained from each type of precursor. Cane sugar (sucrose) and carbon black were used as carbon sources. Reaction conditions studied were carbon to alumina ratio, temperature and reaction time. Sucrose resulted in a close-to-stoichiometric ratio of Al$ sb2$O$ sb3$:C (1:3.2) achieving full conversion to AlN and produced a regular powder morphology, whilst carbon black required higher ratio ($>$1:4) to reach full conversion with agglomeration of the AlN powder. The optimal reaction temperature was 1600$ sp circ$C with the reaction time being dependent on the Al$ sb2$O$ sb3$ source. The results of the thermodynamic study for the Al-N-O-C system suggest a solid-state reaction process which is consistent with the experimental observations. Moreover, flowing N$ sb2$ gas flushes out the product CO gas and thus forces the equilibrium in favour of AlN formation. Reaction mechanisms are proposed for the two forms of carbon precursor.
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King, David M. "The synthesis of terminal uranium nitride complexes." Thesis, University of Nottingham, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602533.
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The study of metal-ligand multiple bonding has provided significant insights into the electronic structure and behaviour of the transition metals, however the chemistry of uranium has been restricted to U-L double bonds such as uranyl, terminal chalcogenides, imides and carbene complexes. Of particular note, is the absence of the identification and isolation of terminal uranium-nitride complexes, U=N. The uranium-nitride linkage not only presents the opportunity to advance our understanding of the 5f orbitals and their participation in bonding, but uranium nitride also offers potential industrial applications. Uranium-nitride is currently under consideration as a future nuclear fuel source in preference to the traditional uranium oxides, due to its higher melting point, density and thermal conductivity. However despite numerous attempts to isolate a terminal U=N bond, molecular methods have thus far proved unsuccessful. Herein the syntheses of the first terminal uranium-nitride complexes are reported. The reaction ofPyTMsH (p/MS = CsH4N-2-NSiMe3) with I1BuLi afforded the ligand transfer reagent [{ Li(Py TMS)(THF) } 2]' Salt metathesis reaction of three equivalents of [{Li(P/MS)(THF) h] with [UX4] eX = Cl, I) afforded the uranium(lV) halide complexes [U(X)(P/MS)3]. Attempts to reduce [U(X)(pyTMS)3] to the hypothetical uranium(III) species were unsuccessful and only the uranium(lV) homoleptic complex [U(P/MS)4] could be isolated. A novel sterically demanding ligand architecture Tren TIPSH3 [Tren {N(CH2CH2NR)3} 3-, TIPS = Siipr3] has been synthesised with the sole aim of stabilising uranium-ligand multiple bonding. The pro-ligand [Li3(Tren TIPs)] was synthesised in good yield and subsequently transferred to uranium through salt metathesis to afford the uranium halide complexes [U(X)(Tren TIPS)]. These uranium(IV) species can be reduced with potassium to afford the first crystallogaphically characterised Tren derived uranium(III) complex, [U(Tren TIPS)]. Uranium(IV) azide complexes have been noted as potential precursors to uraniumnitride formation through photolysis. Consequently a series of novel uranium(lV) azide complexes have been synthesised and characterised supported by the TrenR (R The Synthesis of Terminal Uranium Nitride Complexes = SiMe3, Si'BuMe2, Siipr3) ligand framework. Interestingly the steric bulk plays a key role in controlling the extent of aggregation. The photolysis of the uranium azide species [{U(TrenDMBS) }4(Il:r(r{N3)4] led to the isolation of the mixed valent bimetallic uranium (IV IV) nitride complex [{U(TrenDMBS) h(Il-N)], which is best formulated as containing a [U-N=U] core. In contrast, photolysis of the terminal azide complex [U(N3)(Tren TIPS)], resulted in intitial N2 evolution to yield a transient uranium(VI) nitride which quickly underwent C-H activation of the ligand to afford the uranium(IV) amido complex [U {(NHCMe2Siipr2NCH2CH2)N(CH2- CH2NSiipr3)2} ]. A two-electron redox reaction of the sterically demanding uranium(III) complex, [U(Tren TIPs)] with sodium azide afforded the dimeric bridging uranium(V) nitride species [{U(Il-N)(Il-K)(Tren TIPS) h]' Abstraction and encapsulation of the sodium cation was achieved through treatment with polydentate crown ether 12-crown-4 to afford the first example of a terminal uranium(V) nitride complex, [U (N)(Tren TIPs)] [N a(l2C4 h]. This species can be oxidised to the neutral terminal uranium(VI) nitride, [U(N)(Tren TIPS)], through oxidation with iodine. [U(N)(Tren TIPs)] exhibits an exceptionally short U=N bond length of 1.799(9) A, consistent with a triple bond. The U=N linkage has been analysed by X-ray diffractometry, 15N-isotopic labelling, electronic absorption and electron paramagnetic resonance spectroscopies, magnetometry, and electronic structure calculations. Additionally the uranium(V) imido complexes [U(NSiMe3)(Tren TIPS)] and [U(NAd)(Tren TIPS)] (Ad = adamantyl) were synthesised through two-electron oxidation of organic azides with [U(Tren TIPS)]. The terminal amido complex [U (NH2)(Tren TIPS)] was synthesised through the reaction of [U (Tren TIPs)] with [NI1BU4] [N3]. Single-molecular-magnets, defined as molecules that exhibit slow relaxation of the magnetisation of purely molecular origin, are intensively researched due to the prospective applications in molecular electronics. Recently chemists have reported a handful of uranium(III) complexes which exhibit SMM behaviour. However observation of slow relaxation is not limited to uranium(lII) species. In this work the first monometallic uranium(V) SMM, [U(O)(Tren TIPs)], synthesised through a two electron oxidation of [U(Tren TIPs)] with Me3NO, is reported. Attempts to synthesise ~ VI ~ n The Synthesis of Terminal Uranium Nitride Complexes the analogous terminal uranium sulphide through various routes only resulted in the isolation of the dinuclear uranium(IV) sulphido complex [{U(Tren TIPS) b(/l-S)]. The isolation of a uranium(V) SMM suggests that uranium may offer a substantial role in the future of SMM chemistry. ~ VII
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March, Andrew Ronald. "Application of nitrile oxide/isoxazoline chemistry in C-glycoside synthesis." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/12565.
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A route to C-glycosides and C-disaccharides with functionalised linkages has been investigated. This convergent strategy involves cycloaddition of selected alkenes and sugar derived nitrile oxide moieties. The resultant 2-isoxazolines can be modified and subsequently ring opened to afford compounds with carbonyl or amino containing linkages. The alkenes selected for study were two w-unsaturated monosaccharide derivatives: 5,6-dideoxy-1,2-O-isopropylidene-a-D-xylo-hex-5-enofuranose and methyl 5,6-dideoxy-2,3-O-isopropylidene-a-D-lyxo-hex-5-enofuranoside. Styrene, oct-1-ene and methylenecyclohexane were also studied as models. Four sugar based nitrile oxides were investigated in cycloadditions to these alkenes, based on D-glucose, D-galactose, D-mannose and L-fucose. Three complementary cycloaddition procedures were developed and evaluated: the dehydration of 2,6-anhydro-1-deoxy-1-nitroalditols, the hypochlorite-mediated oxidative dehydrogenation of pyranosyl oximes, and the dehydrochlorination of a pyranosyl hydroximoyl chloride. The oximes and hydroximoyl chloride compounds were synthesised from the corresponding pyranosylnitromethanes. Reactions involving the sugar oximes typically resulted in variable yields of the by-product furazan N-oxide (furoxan) in addition to the cycloadducts, depending on the dipolarophile reactivity. In contrast, uniformly high yields of cycloadducts (70-90%) were obtained from the nitromethyl compounds and hydroximoyl chloride with a range of dipolarophiles; little or no nitrile oxide dimerisation was observed in these reactions.
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Strachan, Jon-Paul. "The study of nitrile ylides with conjugation in heterocyclic synthesis." Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/14498.
Full textAbstract:
This research concerned with generation and reaction of diene- and triene- conjugated nitrile ylides. The amide precursors were synthesised from readily available reactants via Pd(0) catalysed cross coupling reactions and the nitrile ylides were generated by the 1,3-dehydrochlorination of imidoyl chlorides. Two series of triene-conjugated nitrile ylides were studied; firstly, those in which the α, β:γ, δ bonds were aromatic and then those with an aromatic ring only in the α,β position. The first series reacted via a [3+2] cycloaddition across the olefin double bond, when this was activated towards cycloaddition, to give a dibenz[e,g]indole. The presence of a methyl group at the 2 or 2'-position of the biaryl unit prevented cyclisation, and dimeric products were then observed. When no methyl group was present reaction occurred via 1.7-electrocylisation at the free ortho position of the γ, δ aromatic ring to give dibenz[c,e]azepines. The second series of nitrile ylides in which the γ,δ:ε,ζ double bonds are olefinic cyclised at 0oC to give cyclopropa[c]isoquinolines as primary products. In cases where the terminal double bond was cis these products reacted further by a Cope rearrangement to give 1,4-bridgedisoquinolines. In cases where the terminal double bond was trans the primary product rearranged on heating via a [1,5] carbon shift accompanied by a complex skeletal rearrangement to give an azatetracyclotridecatetraene and to a lesser extent via an equilibration between exo and endo isomers accompanied by a Cope rearrangement to give 1,4-bridgedisoquinolines. The diene-conjugated nitrile ylides cyclised at room temperature to give cyclopropa[c]isoquinolines in a stereospecific reaction. Thermal decomposition of these products involved an equilibration between exo and endo isomers accompanied by ring expansion to give 1H-2-benzazepines or a [1,5]-sigmatropic hydrogen shift to give 1H-isoquinolines or followed another reaction path to give 5H-2-benzazepines.
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Zhang, Xuefei. "Synthesis and Characterization of Zr1-xSixN Thin Film Materials." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/ZhangX2007.pdf.
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