Dissertations / Theses on the topic 'Azimine'

Historiquement les lanceurs utilisaient des technologies peu puissantes, polluantes et très toxiques comme l’hydrazine et ses dérivés. De nouveaux mélanges d’ergols plus puissants ont vu le jour. Les ergols dit cryogéniques LOX/LH2, LOX/kérosène ou encore Lox/méthane présentant des performances bien supérieures. Des propergols solides denses offrent également une forte poussée mais ne peuvent être réallumés ou modulés, c’est le cas des boosters (Aluminium, perchlorate d’ammonium et du PBHT pour les EAP d'Ariane 5). L’objectif actuel est de trouver de nouveaux ergols, possédant les performances des cryogéniques avec la stockabilité des hydrazines ainsi que la densité des solides. Une classe de molécules offre tous ces avantages, ce sont les HEDMs pour High Energy Density Materials. Ces nouvelles molécules énergétiques à haute valeur ajoutée possèdent actuellement des propriétés théoriques calculées, telles que l'impulsion spécifique et la densité, très intéressantes. Elles forment par décomposition, et non par combustion, des gaz de faible masse molaire à très haute vitesse, ce qui permet de s'inscrire dans la dynamique actuelle de réduction des coûts, de la pollution et de la toxicité, ainsi que du dimensionnement du lanceur (Ariane Ultimate). Cela permet également d'augmenter la charge utile en utilisant une quantité moindre d'ergo. La cible souhaitée au cours de cette thèse est la triaziridine N3H3. Ces travaux de thèse s’inscrivent exactement dans cette dynamique et se concentrent sur l’accès à une molécule cyclique triazotée pour la propulsion spatiale : la triaziridine. Pour ce faire, la réactivité des azimines en conditions photochimiques a été étudiée. Il a d’abord été choisi de reprendre des travaux antérieurs effectués au laboratoire et de procéder à une optimisation complète de la réaction de cyclisation dans le but d’augmenter les rendements en triaziridine. Des screenings de solvants, de catalyseurs et d’additifs ont été envisagés, ainsi qu’une transposition en flux continu. Toujours dans le but d’obtenir des triaziridines déprotégeables, une nouvelle méthode de synthèse d’azimine monotope a été développée, reposant sur l’amination électrophile d’une hydrazine fonctionnalisée par une oxaziridine, menant au triazane correspondant. Ce triazane sera par la suite oxydé par un dérivé d’iode hypervalent, permettant l’accès à de tout nouveaux squelettes aziminiques. Pour finir, une étude théorique de modélisation DFT de la réaction de photocyclisation de l'azimine a été explorée. Cette étude montre les différents états de transition permettant la cyclisation de l'azimine en triaziridine. Elle a également permis d'initier le développement d'un modèle dit prédictif, qui guidera le choix des substituants clivables à introduire sur l'azimine pour favoriser la réaction de photocyclisation<br>Since the begining of space propulsion, launchers used low-power, polluting, and highly toxic technologies such as hydrazine and its derivatives. New, more powerful propellant mixtures have emerged. Cryogenic propellants like LOX/LH2, LOX/kerosene, or LOX/methane show significantly higher performance. Dense solid propellants also offer high thrust but cannot be reignited or throttled. This is the case with boosters (aluminum, ammonium perchlorate, and PBHT for Araine 5's EAP). The current goal is to find new propellants that possess the performance of cryogenics, the storability of hydrazines, and the density of solids. A class of new molecules offers all these advantages : High Energy Density Materials (HEDMs). These new high-value-added energetic molecules currently have theoretically calculated properties such as specific impulse and density, which are very interesting and in total technological breakthrought. They form gases with low molar weight at very high speeds through decomposition rather than combustion, aligning with the current trend of reducing costs, pollution, and toxicity, as well as the launcher’s size (Ariane Ultimate). This also allows for an increase the payload by using a smaller amount of propellant. The desired target of this thesis is triaziridine N3H3. This thesis work fits exactly within this dynamic and focuses on accessing a cyclic trinitrogenated molecules for space propulsion: triaziridine. To do this, the reactivity of azimines under photochemical conditions was studied. Initially, it was decided to build upon previous work conducted in the laboratory and to proceed with a complete optimization of the cyclization reaction to increase yields of triaziridine. Solvents, catalysts, and additives screenings were considered, and continuous flow transposition. Still aiming to obtain deprotectable triaziridines, a new one-pot method for azimine synthesis was developed, based on the electrophilic amination of functionalized hydrazine by an oxaziridine, leading to the corresponding triazane. This triazane will subsequently be oxidized by a hypervalent iodine derivative, allowing access to brand new aziminic skeletons. Finally, a theoretical DFT modeling study of the azimine photocyclization reaction was explored. This study shows the differents transition states that allow the cyclization of azimine into triaziridine. It also been initiated the development of a predictive model, which will guide the choice of cleavable substituents to introduce on the azimine to promote the photocyclization reaction

Tese (doutorado)—Universidade de Brasília, Instituto de Geociências, 2013.<br>Submitted by Jaqueline Ferreira de Souza (jaquefs.braz@gmail.com) on 2014-05-27T15:17:25Z No. of bitstreams: 1 2013_LoianeGomesdeMoraisRocha_Parcial.pdf: 13027446 bytes, checksum: 18463463cbd5c91e4bf88adc815a8756 (MD5)<br>Approved for entry into archive by Patrícia Nunes da Silva(patricia@bce.unb.br) on 2014-05-27T15:26:36Z (GMT) No. of bitstreams: 1 2013_LoianeGomesdeMoraisRocha_Parcial.pdf: 13027446 bytes, checksum: 18463463cbd5c91e4bf88adc815a8756 (MD5)<br>Made available in DSpace on 2014-05-27T15:26:36Z (GMT). No. of bitstreams: 1 2013_LoianeGomesdeMoraisRocha_Parcial.pdf: 13027446 bytes, checksum: 18463463cbd5c91e4bf88adc815a8756 (MD5)<br>A área de estudo envolve parte do Lineamento Azimute 125° (Az 125°), localizado nos estados de Goiás e Minas Gerais, e perfaz um extenso conjunto de falhas com direção NW-SE, formado durante o Evento Orogênico Brasiliano (iniciado há cerca de 950 Ma), que serviu como conduto para ascensão de magma. Na área de estudo, o Az 125° constitui uma feição com cerca de 850 km de extensão e 70 km de largura. Ao longo deste lineamento estão os mais importantes complexos carbonatíticos e kimberlíticos do Brasil o que lhe confere o caráter de principal feição estrutural associada a essas províncias. Contudo, o Az 125° não é cartografado em mapas geológicos, em escala regional, como feição contínua por não apresentar expressão persistente em superfície ou em imagens de satélite. Ao longo do Az 125° ocorrem províncias geológicas com mineralizações de grande relevância econômica, atribuindo à área importância geológica. Entretanto, poucos estudos do Az 125° são encontrados na literatura. Nesta tese, propõe-se contribuir com o conhecimento desse Lineamento a partir de sua relevante assinatura magnética que lhe caracteriza como um conjunto de feições lineares de continuidade regional em subsuperfície que é realçado por uma resposta de susceptibilidade magnética contrastante com aquelas apresentadas por suas rochas encaixantes. Com base nas assinaturas magnéticas e nas rochas ígneas básicas mapeadas em campo, o Azimute é compartimentado em três sistemas principais de lineamentos L1, L2 e L3, formados na mesma época, porém, afetados por dois ou três eventos tectono-magmáticos distintos. O primeiro evento ocorreu durante ciclos de orogêneses do Brasiliano (950 Ma a 520 Ma). O segundo aconteceu durante a fragmentação do Gondwana (cerca de 180 Ma). O terceiro está associado à passagem da Pluma de Trindade (90 Ma a 80 Ma), e pode ter sido fonte de injeção de magma apenas em determinadas partes do Az 125°. O Sistema L1 compreende os diques mais antigos, o Sistema L3 os mais jovens e o Sistema L2 com idade intermediária, ao longo do qual são destacadas anomalias magnéticas associadas às rochas intrusivas das províncias alcalinas de Goiás (PAGO) e Alto Paranaíba (PAAP). Os dados obtidos em campo suportam aqueles apresentados pela geofísica e caracterizam o Lineamento como um conjunto de diques formados por rochas gabróicas e diabásios que afloram pontualmente devido à ação de processos erosivos. Os dados aeromagnéticos também foram utilizados para estimar as profundidades Curie da área de estudo pelo método de aproximação espectral. A profundidade Curie é aquela na qual as rochas são afetadas pelo calor (temperatura Curie) a ponto de perderem suas propriedades magnéticas. Cerca de 500 pontos foram utilizados para estimar as profundidades Curie. A distribuição espacial dessas profundidades permitiu a geração de um mapa de superfície Curie. Esse mapa mostra um intervalo de profundidades que varia de 7 km a 40 km. As profundidades mais rasas estão relacionadas às regiões onde se localizam a PAGO e PAAP, e as mais profundas associam-se à Placa São Franciscana. As profundidades Curie relativas ao Az 125° estão entre 30 km e 16 km. Os resultados de profundidades Curie revelam que os corpos intrusivos da PAGO e da PAAP possuem base mais rasa do que a dos diques que formam o Lineamento. A contribuição deste estudo é a caracterização geofísica do Lineamento Az 125° pela determinação de uma cronologia dos eventos que caracteriza a estrutura segmentada do Az 125°, definida aqui como os sistemas L1, L2 e L3, com base em dados geofísicos e geológicos. _______________________________________________________________________________________ ABSTRACT<br>The study area includes a portion of the Azimuth 125° lineament (Az 125°). This lineament is located in the Brazilian states of Goiás and Minas Gerais and consists of an extensive set of faults that are oriented in the NW-SE direction. The Az 125° feature is approximately 850 km long and 70 km wide. The formation of these faults probably occurred during the Brasiliano Orogenic Event (started at ca. 950 Ma) and they served as a conduit for magma ascent. The most important carbonatite and kimberlite complexes in Brazil are located along this lineament which is the main structural feature that is associated with these complexes. However, Az 125° is not mapped on geological maps at a regional scale as a continuous structural feature, because it is not consistently visible on the surface or in satellite images. Geological provinces with highly economically valuable mineralizations occur along Az 125°. These provinces make this area geologically important. The present study is a contribution to the advancement of knowledge of Az 125°, based on its relevant magnetic signature. This signature characterizes the lineament as a set of linear features with regional continuity in the subsurface, where it is highlighted by a magnetic susceptibility response that contrasts with the response that is exhibited by its host rocks. The azimuth is partitioned into three main systems (L1, L2, and L3) according to its magnetic signatures and mapped igneous rocks cronology. They were generated at the same time, but were affected by two or three distinct tectono-magmatic events. The first event occurred during the Brasiliano (950 Ma to 520 Ma). The second event occurred during the Gondwana fragmentation (starting circa 180 Ma). The third event is related to the tectonomagmatic activity of The Trindade plume (90 Ma to 80 Ma), and maybe it was source of magma injection only in certain portions of the Az 125°. The L1 system includes the older dikes, and the L3 system includes the youngest dikes; the L2 system which intersects L3, is therefore, of intermediate age. Magnetic anomalies that occur along Az 125° are associated with intrusive rocks from the Goiás and Alto Paranaíba alkaline provinces. The field data support the geophysical data and define the Az 125° lineament as a set of dikes of different ages. These dikes are formed by gabbroic rocks and diabase and can be observed in occasional outcrops that resulted from active erosion. Aeromagnetic data were also used to estimate the Curie depths of the study area by the spectral approach. Curie depths are those at where the bodies causing magnetic anomalies become non-magnetic properties above the Curie temperature of their minerals. These depths were evaluated for approximately 500 locations. The spatial determination of several Curie depths allowed the delineation of a Curie surface map. This map shows a range of depths from 7 km to 40 km deep in the study area. The shallower depths are related to the Goiás (GAP) and Alto Paranaíba (APAP) Alkaline Provinces regions, and the deeper to the São Franciscana Plate. The Curie depths related to the Az 125° are between 30 km and 15.7 km deep. According to the Curie depths results, the GAP and APAP intrusive bodies have shallower offsets when compared to the Az 125° major faults. An important contribution of this study concerns the geophysical characterization of the Az 125° lineament by the determination of a chronology of events that characterizes the segmented structure of the Az 125°, here defined as L-systems (L1, L2, and L3), based on both geological and geophysical data, and not yet reported in earlier studies.