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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Le marché de l'aluminium : structuration et analyse du comportement des prix au comptant et à terme au London Metal Exchange

Mouak, Prosper 03 March 2010 (has links) (PDF)
Dans les années 60 et avant, le marché international de l'aluminium était présenté comme un cas d'école en matière d'organisation oligopolistique des firmes. En effet, un petit nombre de grands groupes fortement intégrés (les 6 Majeurs) contrôlaient la quasi-totalité du secteur de l'aluminium, des opérations d'extraction de la bauxite, à la fabrication de produits finis à base d'aluminium, en passant par la production d'alumine et d'aluminium en lingots. A partir des années 70, ce monopole est de plus en plus contesté, notamment par des entreprises sur-liquides venues principalement des secteurs miniers et par des entreprises étatiques porteuses de motivations différentes. La création en décembre 1978 du contrat Aluminium au London Metal Exchange (LME) sonne le glas du monopole constitué par les 6 Majeurs. On passe alors d'un système de prix- producteurs, à un véritable système de prix de marché L'objectif de cette thèse est de vérifier, si le LME, bourse pionnière et marché de référence pour les métaux non-ferreux, remplit efficacement ses fonctions financières concernant l'aluminium : Information sur les prix et l'état du marché, protection contractuelle contre les risques de fluctuations des prix, stabilisation des cours.
2

The Coupling Mechanism in the Organolithium-Organic Monofluoride Reaction

Carl, William P. 05 1900 (has links)
In this work, the principal concern will be with the coupling reaction and it is anticipated that the other reactions referred to above will be considered further when products of the RX-R'Li reactions are discussed.
3

Le marché de l'aluminium : structuration et analyse du comportement des prix au comptant et à terme au London Metal Exchange / The aluminium market : analysis of the structure and movement of spot and futures prices at the London Metal Exchange

Mouak, Prosper 03 March 2010 (has links)
Dans les années 60 et avant, le marché international de l’aluminium était présenté comme un cas d’école en matière d’organisation oligopolistique des firmes. En effet, un petit nombre de grands groupes fortement intégrés (les 6 Majeurs) contrôlaient la quasi-totalité du secteur de l’aluminium, des opérations d’extraction de la bauxite, à la fabrication de produits finis à base d’aluminium, en passant par la production d’alumine et d’aluminium en lingots. A partir des années 70, ce monopole est de plus en plus contesté, notamment par des entreprises sur-liquides venues principalement des secteurs miniers et par des entreprises étatiques porteuses de motivations différentes. La création en décembre 1978 du contrat Aluminium au London Metal Exchange (LME) sonne le glas du monopole constitué par les 6 Majeurs. On passe alors d’un système de prix- producteurs, à un véritable système de prix de marché L’objectif de cette thèse est de vérifier, si le LME, bourse pionnière et marché de référence pour les métaux non-ferreux, remplit efficacement ses fonctions financières concernant l’aluminium : Information sur les prix et l’état du marché, protection contractuelle contre les risques de fluctuations des prix, stabilisation des cours. / In the 1960s and before, the international aluminium market has been hold up as a paradigm for oligopolistic company organisation. A small number of strongly integrated conglomerates (the six Majors) did indeed control virtually the entire aluminium sector, from bauxite extraction to alumin and aluminum bar production as well as the manufacturing of finished aluminium products. From the 1970s onwards, this monopoly has been more and more called into question, in particular by cash-fuelled mining corporations and state-owned companies driven by different motivations. When the London Metal Exchange (LME) introduced the Aluminium contract in December 1978, the days of the 6 Majors’ monopoly were counted. From there on, prices have been fixed by producers and the market. This thesis aims at determining whether the LME, a pioneering exchange and the prime market for non-iron metals, efficiently fulfils its financial functions concerning aluminium: information about prices and the market situation, legal protection against price fluctuation risks, price stabilization.
4

Synthesis of potential opioids based on the natural Pawhuskins

Gardner, Kevyn Danielle 01 May 2016 (has links)
Living organisms are capable of producing novel terpenoids with both remarkable ease and great selectivity. Many of these natural products exhibit significant biological activity useful for treatment of human diseases, but isolation of highly sought chemicals often results in only minute quantities. Consequently, extraction of these potential therapeutics from natural sources becomes an unrealistic method for obtaining enough material for a thorough biological evaluation, and so synthesizing these compounds becomes essential. Synthesis of terpenoids as potential therapeutics requires exceptional selectivity, especially when corresponding isomers elicit a contrasting biological response. The necessity for such selective syntheses along with the inherent structural complexities of terpenoids, often presents a number of significant challenges for the synthetic chemist. Isolation of the terpenoids pawhuskins A–C and petalostemumol from Dalea purpurea was reported by Belofsky in 2004, and of the collected compounds pawhuskin A was found to exhibit the most significant activity in an opioid receptor assay in vitro. Natural pawhuskin A was extracted from “Purple Prairie Clover” in only a 39 mg quantity and therefore syntheses of the natural product along with several analogues were pursued. Two of the synthesized analogues demonstrated greater potency than pawhuskin A, and interestingly these two isomeric derivatives were found to be selective for two different opioid receptors. However, the synthetic route utilized to form these two derivatives was not very selective for either isomer, and thorough purification proved challenging. Ergo, an alternative approach was sought to ensure the purity of these potential therapeutics. Parallel syntheses affording high selectivity for the key isomeric intermediates as well as a third regioisomer have been developed. The new isomeric intermediate also allowed the synthesis of two new analogues. This work is described in this report along with the formation of additional pawhuskin derivatives. The activity of these analogues as opioid receptor modulators also will be discussed.
5

Investície podniku automobilového priemyslu do kovov ako strategických surovín / Investments of Automotive Industry in Metals as Strategic Materials

Kubík, Ján January 2020 (has links)
This diploma thesis deals with the fundamental analysis of selected metals as commodities, for use in the production of batteries for electric vehicles, to hedge against changes in the price of physical raw materials. Selected metals are analyzed based on the fundamental parameters, historical price development and the current situation on the commodity market. Based on these fundamental data, a recommendation is formulated for the method of hedging the prices of selected commodities.
6

Stereoselective synthesis & application of enantioenriched main group α-haloalkyl organometal reagents

Emerson, Christopher R. 10 November 2011 (has links)
Sulfoxide-ligand exchange (SLE) and asymmetric halogen-metal exchange (AHME) processes were separately examined for the enantioselective synthesis of functionalized alpha-haloalkylmetal (carbenoid) reagents. Carbenoids derived from SLE were used to effect stereospecific reagent-controlled homologation (StReCH) of boronic esters and those generated via AHME were engaged in Darzens-type chemistry with aldehydes. Abstract for Part 1. Scalemic syn alpha-chloroalkylsulfoxides p-TolS(O)CHClR [R = allyl, (1,3-dioxolan-2-yl)methyl, proparygyl, and 2-(benzyloxy)ethyl] were prepared from the corresponding thioethers by Jackson-Ellman-Bolm catalytic enantioselective sulfoxidation [cat. VO(acac)₂, tert-leucinol derived chiral Schiff base ligand, aq. H₂O₂, CHCl₃; 76-80% yield, >98% ee] followed by non-racemizing chlorination mediated by N-chlorosuccinimide in the presence of potassium carbonate (84-86% yield, syn:anti ≥ 20:1). The corresponding anti diastereoisomers were accessed from their syn epimers by sodium hexamethyldisilazide mediated deprotonation (THF, –78 °C) followed by treatment with either CH₃OH or CD₃OD to yield alpha-[¹H] or alpha-[²H] isotopomers, respectively (88% yield, anti:syn ≥ 17:1). Allyl and (1,3- dioxan-2-yl)methyl substituted chlorosulfoxides reacted with R'Li (t-BuLi or PhLi, THF, –78 °C) to give the expected products of SLE [p-TolS(O)R' and LiCHClR or LiCDClR]; however, neither the benzylether nor propargyl substituted substrates gave wholly satisfactory results under the same reaction conditions. The functionalized carbenoid reagents so obtained, 1-chloro-3-butenyllithium and 1-chloro-2-(1,3- dioxolan-2-yl)ethyllithium, were applied to the StReCH of B-(2-chloropyrid-5-yl) pinacol boronate but only the latter gave acceptable yields of chain extended products. The anti alpha-[²H]-chlorosulfoxide dioxolanyl bearing carbenoid precursor gave superior results to the analogous syn or anti alpha-[¹H]-chlorosulfoxides for StReCH of the B-pyridyl boronate [79% conversion, ≥ 89% ee (99% stereofidelity), vs. ≤ 68% conversion for non-deuterated chlorosulfoxides]. The origin of this isotope effect was traced to a deleterious proton transfer pathway between the alpha- chloroalkyllithium reagent and its chlorosulfoxide precursor. Sequential double iterative StReCH of B-(2-chloropyrid-5-yl) pinacol boronate with two separate portions of (S)-1-[²H]-1-chloro-2-(1,3-dioxolan-2-yl)ethyllithium (generated via SLE with phenyllithium) followed by oxidative work-up (with KOOH) gave (1R,2R)-1,2- [²H]₂-2-(2-chloropyrid-5-yl)-1,2-bis[(1,3-dioxolan-2-yl)methyl]ethanol (40% yield, ≥ 98% ee, dr = 85:15). Substitution of the (R)-configured carbenoid for its antipode in the second StReCH stage above gave the unlike (1S,2R)-isomer of the same pyridylethanol derivative (49% yield, ≥ 98% ee, dr = 79:21). The unlike diastereoisomer was advanced to the trifluoroacetamide of (1R,2R)-1,2-[2H]2-1- amino-2-(2-chloropyrid-5-yl)cyclohex-4-ene (6 steps, 5% overall yield); the non- deuterated isotopomer of this compound was previously advanced to the analgesic alkaloid (–)-epibatidine by Corey and co-workers. Abstract for Part 2. Scalemic planar chiral N,N-dialkyl 2-iodoferrocene carboxamides envisioned as recyclable precursors to ferrocenyl metal reagents for AHME, were prepared from ferrocene carboxylic acid by a three step sequence of: acid chloride formation [(COCl)₂ and cat. DMF)], aminolysis (with R₂NH, R = Me, Et, i-Pr; 65- 80% yield over 2 steps), and sec-butyllithium/(–)-sparteine mediated enantioselective directed ortho-metallation (DoM) followed by iodinolysis (87% yield, ≥ 96% ee). Attempts to access more elaborate 5-substituted 2-iodoferrocene carboxamides via DoM/iodinolysis of ortho-substituted ferrocene carboxamides (Me, Ph, or SiMe₃ substituents) mostly failed; however, analogous trisubstituted ferrocene oxazolines could be synthesized. Treatment of N,N-diisopropyl 2-iodoferrocene carboxamide (298, ≥ 96% ee) with n-BuLi (THF, –78 °C) resulted in complete conversion to the corresponding lithioferrocene (327) via I/Li interchange; subsequent iodinolysis initiated reverse Li/I exchange and returned iodoferrocene 298 without diminished enantiomeric excess, establishing configurational stability for the lithiated ferrocene intermediate. Prochiral (RCHI₂) and racemic (RCHICl) geminal dihalide substrates for AHME studies were prepared by electrophilic quench of dihalomethylsodiums with either Ph(CH₂)₃I or Me₃SiCl (50-78% yield). Of the four dihalides so produced, only prochiral substrate Me₃SiCHI₂ engaged in I/Li exchange with scalemic lithioferrocene 327 resulting in regeneration of its precursor iodoferrocene 298 and the formation of a putative chiral carbenoid Me₃SiCHLiI. Trapping of the carbenoid with aldehydes RCHO (R = Ph, 4-MeOC₆H₄, Ph(CH₂)₂, c-C₆H₁₁) in the presence of Me₂AlCl gave the expected epoxysilane products (35-40% yield, cis:trans ≥ 2:1) but without discernable enantiomeric excess. Hypotheses to account for the apparent lack of stereoinduction in this AHME cycle are presented. Comparable experiments using analogous magnesiated ferrocenes failed to produce putative carbenoid species from the same set of geminal dihalide substrates. / Graduation date: 2012
7

Využití umělé inteligence na burze kovů pro podporu rozhodování firmy / The use of Artificial Intelligence for Exchange with Metal to Support Decision-making of Firm

Elhenický, Jan January 2014 (has links)
This master thesis deals with issues connected with using artificial intelligence in metal exchange. It describes theoretical bases of financial markets, various methods of analyses and artificial intelligence. Main accent is put on creating functional models in Matlab program which will predicate incoming values of time series. Part of the thesis is description of company, for which are those models of neural networks for supporting decision making created.
8

Aplicação de reagentes organometálicos na funcionalização de indolizinas de interesse sintético / Application of organometallic reagents in the functionalization of indolizines of synthetic interest

Toledo, Mônica Franco Zannini Junqueira 30 January 2015 (has links)
Nos últimos anos, houve um aumento considerável dos estudos envolvendo o núcleo indolizínico, um entre os milhares de heterociclos existentes, sendo 2012 o ano de maior destaque, com 102 publicações. Esse crescente interesse é atribuído principalmente à busca por novos substratos funcionalizados que apresentem características medicinais e biológicas. Todavia, as indolizinas ainda são pouco exploradas se comparadas a outros núcleos heterocíclicos, principalmente no que diz respeito a sua funcionalização por emprego de reagentes organometálicos. Desta forma, o objeto deste trabalho foi o estudo da reatividade de diversas indolizinas perante diferentes organometálicos, por meio de reações de metalação dirigida, troca iodo-magnésio e acoplamento cruzado de Negishi com o intuito de construir indolizinas polifuncionalizadas. Assim sendo, inicialmente foi estudada a reatividade de bases organometálicas diante de algumas indolizinas e as reações de seus intermediários organometálicos com uma variedade de eletrófilos. Para tanto, as indolizinas foram divididas por posicionamento das funcionalizações, ou seja, indolizinas funcionalizadas na posição 1 do anel (-CO2Et, -CO2tBu e CN), indolizinas funcionalizadas na posição 2 do anel (-CO2Et, CN) e indolizinas funcionalizadas nas posições 1 e 3 do anel. Na sequência, foram estudadas as reações de troca iodo-magnésio diante das indolizinas funcionalizadas nas posições 1 e 3 e, por último, as reações de metalação dirigida com os substratos 2-arilindolizínicos seguidas por reações de acoplamento cruzado de Negishi. As moléculas sintetizadas nesta última etapa, por terem apresentado fortes propriedades fluorescentes, foram submetidas a um estudo minucioso sobre essas características. Essas estratégias sintéticas desenvolvidas no presente trabalho foram altamente eficientes, permitindo o preparo de uma série de compostos com grande diversidade estrutural, sendo sintetizadas 64 indolizinas polifuncionalizadas inéditas e 11 indolizinas polifuncionalizadas já descritas na literatura por meio de outras metodologias, com rendimentos variando de 15% a 87%. / In recent years, there has been a considerable increase in studies involving the indolizinic core, one of thousands of existing heterocycles, with 2012 being the most outstanding year, with 102 publications. This growing interest is mainly attributed to the search for new functionalized substrates that have medicinal and biological characteristics. However, indolizines are unexplored when compared to other heterocycles, particularly regarding their functionalization with the use of organometallic reagents. Thus, the object of this work was the reactivity study of several indolizines with different organometallics by means of directed metalation reactions, iodine-magnesium exchange and Negishi cross-coupling, in order to build functionalized poly-indolizines. Therefore, initially, it was investigated the reactivity of organometallic bases upon some indolizines and the reactions of their organometallic intermediates with a variety of electrophiles. To achieve this, indolizines were divided according to their function position, i.e. indolizines functionalized at position 1 of the ring (-CO2Et, CN and -CO2tBu), indolizines functionalized at position 2 of the ring (-CO2Et, CN) and functionalized at positions 1 and 3 of the ring. Furthermore, the iodine-magnesium exchange reactions of indolizines functionalized at positions 1 and 3 were studied and, finally, directed metalation reactions with 2-aryl indolizinic substrates followed by Negishi cross-coupling reactions were performed. The ultimate products of such reactions showed strong fluorescent properties and, for this reason, were subject of detailed studies on these characteristics. The synthetic strategies developed in this research were highly efficient, enabling the preparation of a large number of compounds with structural diversity, having been synthesized 64 novel poly-functionalized indolizines and 11 known poly-functionalized indolizines, with yields ranging from 15% to 87%.
9

Aplicação de reagentes organometálicos na síntese de novos derivados quinolínicos de interesse medicinal / Application of organometallic reagents in the synthesis of new quinoline derivatives of medicinal interest

Nicolino, Paula Valim 24 July 2015 (has links)
O núcleo quinolínico constitui uma das classes de heterociclos nitrogenados de maior destaque, pois são amplamente encontradas em produtos naturais, além de comporem a lista dos considerados esqueletos \"privilegiados\", relacionados com as diversas classes terapêuticas como: anticâncer, anticolinesterásicos, antimaláricos, etc. Diante das abordagens sintéticas de funcionalização de anéis heteroaromáticos, o uso de espécies organometálicas ocupa, hoje, uma posição central na química orgânica sintética, principalmente na formação de novas ligações carbono-carbono. Dessa forma, o presente trabalho explorou essencialmente a reatividade de quinolinas frente à reagentes organometálicos tais como alquil-lítio, amidetos de lítio, turbo-Grignard e amidetos mistos de magnésio e lítio. Inicialmente, foi estudada a funcionalização da 4,7- dicloroquinolina através da reação de metalação dirigida frente aos diferentes reagentes disponíveis. Em seguida, foi desenvolvida uma metodologia de troca iodo-magnésio para a 7-cloro-4-iodoquinolina visando a obtenção de derivados funcionalizados na posição C4 bastante estratégica para atividade antimalárica. Neste estudo foi utilizado o reagente turbo-Grignard para etapa de troca, seguida da reação com eletrófilos. Os compostos obtidos tiveram sua atividade antimalárica avaliada pelo grupo do Dr. Adrian M. Pohlit do Instituto Nacional de Pesquisas da Amazônia (INPA). A metodologia de troca iodomagnésio do turbo-Grignard frente à 7-cloro-4-iodoquinolina também foi aplicada para a obtenção de outros derivados por reações de acoplamento cruzado de Negishi, e na rota sintética de um híbrido molecular planejado com potencial atividade antimalárica. Além disso, foi estudada a reação de troca halogênio-metal da 3-bromoquinolina frente a reagentes de lítio seguida da reação com aldeídos. Por fim, algumas das estruturas sintetizadas também tiveram avaliação da atividade anticâncer realizada pelo grupo da Prof. Dra. Letícia Lotufo da Universidade Federal do Ceará. Portanto, foram demonstradas neste trabalho estratégias simples e eficientes utilizando reagentes organometálicos para funcionalização de quinolinas de interesse sintético e medicinal. / The quinoline unit is one of most important nitrogen heterocycle classes since it is found in a large number of natural products. Moreover, it is considered a privileged scaffold presenting a variety of pharmacologic activities such as: anti-cancer, anticholinesterase, antimalarial and others. Among the available aromatic heterocycle functionalization approaches, the organometallic chemistry have a prominent position mainly on the construction of new carbon-carbon bonds. In this context, this work have explored the quinoline reactivity against organometallic reagents like alkyl-lithium, lithium amides, turbo-Grignard and magnesium lithium amides. Initially, the functionalization of 4,7- dichloroquinoline was studied through the direct metalation reaction of the substrate with several available organometallic reagents. Afterwards, a new iodo-magnesium exchange methodology for the 7-chloro-4-iodoquinoline was developed in order to obtain C-4 functionalized quinoline derivatives. The turbo-Grignard was the reagent of choice in iodo-magnesium exchange reactions that were subsequently reacted with different electrophiles. The antimalarial activity of the compounds obtained in this study was evaluated by Dr. Adrian M. Pohlit group of National Institute of Amazon Research (INPA). The developed iodo-magnesium exchange methodology was further applied in Negishi cross-coupling reactions and on a synthetic study of a planned molecular hybrid with potential antimalarial activity. In addition, the halogen-metal exchange reaction on 3-bromoquinoline was studied using alkyl-lithium reagents with subsequent reaction with aldehydes. Finally, the anti-cancer activity of some of structures obtained in this work was evaluated by Prof. Dra Letícia Lotufo group of Federal University of Ceará
10

Is opacity-induced minor metal market volatility a threat to promising green technologies? : A study of the tellurium market

Söderqvist, Fredrik January 2013 (has links)
Tellurium is one of the rarest metals in the earth’s crust. Increased demand for cadmium telluride photovoltaic cells along with an opaque pricing and quantity-reporting system, have recently caused high price volatility and a speculative bubble in the tellurium market, resulting in overstocking and depressed prices. In a longer perspective this may be a threat to cadmium telluride photovoltaics as a power-generating technology. This master thesis compares how actors may perceive news innovation in the opaque tellurium market compared to the more transparent molybdenum market. A quantitative analysis of industry news reporting on the two metals, combined with a SVAR impulse response analysis, helps me determine which actors and factors exert most influence on spot market prices. In the opaque tellurium market, relatively unreliable proxies of supply and demand are most frequent in the news reporting while having a big impact on prices, whereas the transparent molybdenum market uses more reliable variables – such as futures prices – and transparent supply information, whilst also relying on a frequent stream of dependable proxies to scope market sentiments. My findings lead me to recommend policy makers to implement measures to increase market transparency, which may be accomplished by extending the data-sharing regime of the REACH database to minor metal markets. Attempting to limit speculation in minor metal markets is perhaps too blunt a tool to fix an inherent problem of a free exchange-pricing mechanism. / Tellur är en av de mest sällsynta metallerna på Jorden. Ökad efterfrågan av kadmiumtelluridsolpaneler har nyligen orsakat stor volatilitet på tellurmarknaden. Ett opakt prissättnings-och kvantitetsrapporteringssystem har bidragit till att en prisbubbla bildats och spruckit, vilket resulterat i att marknadsaktörer köpt på sig stora lager till höga priser som de sedan inte kunnat sälja vidare. I ett längre perspektiv kan detta innebära begränsningar vid tillverkning av solcellsteknologi baserad på kadmiumtellurid, då ett volatilt pris kan göra nya tellurgruvprojekt alltför riskabla. Denna masteruppsats jämför hur en typisk marknadsaktör kan reagera på prisinnovationer i den opaka tellurmarkanden och den mer transparenta molybdenmarknaden. Metoden består av en kvantitativ analys av facknyheter rörande de två metallerna, varifrån variabler väljs till en SVAR modell med impuls-responsanalys. Urvalet av variabler är få och volatila på den opaka tellurmarknaden, medan den mer transparenta molybdenmarknaden har ett större utbud av variabler som kännetecknas av god transparens och relativ förutsägbarhet. Mina slutsatser leder mig till att rekommendera beslutsfattare att vidta åtgärder för att öka tellurmarknadens transparens genom EU-samarbetet, förslagsvis genom att göra anonymiserad data från REACH databasen tillgänglig för allmänheten. Samtidigt avråder jag från åtgärder som syftar till att minska spekulation, då implementering av en sådan policy kan bli både dyr och komplicerad.

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