Nos últimos anos, questões ambientais têm merecido destaque na mídia nacional e internacional. A química tem uma grande participação nos dias atuais com os inúmeros produtos fundamentais à humanidade. A sua presença pode ser destacada desde diversos combustíveis aos mais complexos medicamentos. As reações de síntese orgânica devem ser guiadas por novas práticas mais sustentáveis. Nesse campo, tem-se o conceito da Green Chemistry ou Química Verde, que consiste na estratégia em desenvolver metodologias e processos que usem e gerem a menor quantidade de materiais tóxicos e/ou inflamáveis ou reaproveitáveis. Com o intuito de contribuir com a Química Verde, estudou-se a síntese de iminas que consistiu da primeira etapa do processo de aminação livre de solventes orgânicos e apresentaram rendimentos superiores a 95,0 %; gem-dicloroaziridinas foram preparadas a partir de inserção de diclorocarbeno em iminas em condições mínimas de solvente orgânico, utilizando como catalisador o KF/Al2O3 e com rendimentos superiores a 98,0%. As gem-dicloroaziridinas foram convertidas em amidas por hidrolise, na ausência de solvente e com rendimentos superiores a 98,0%. Dentro do conceito de Química Verde foram preparadas as seis iminas: N-benzilfenilmetanoimina, N-fenil-furilmetanoimina, N-fenilfenilmetanoimina, N-fenil-(4-metoxifenil)-metanoimina, N-benzil-(4-metoxifenil)metanoimina e N-furfurilfurilmetanoimina; duas gem-dicloroaziridinas: 2,2-dicloro-1,3-difenilaziridina e 1-benzil-2,2-dicloro-3-fenilaziridina e duas amidas: cloro-fenilacetanilida e N-benzil-cloro-fenilacetamida. / For the last years Environmental issues have deserved featured in the National and International media. Chemistry has had great participation on currently days with countless products which are fundamental to humanity. Its presence can be detached from various fuels to the most complex drugs.The organic synthesis reactions should be guided by more sustainable new practices. In this field, the Green Chemistry concept or (Química Verde) strategy which aims to develop methodology and and/or processes which use and generate the minimum quality of toxic inflammable material. With the purpose of contribute to green chemistry, we studied the synthesis of imines which consisted of the first stage of the process of amination, free of organic solvents and have yields higher than 95%; gem-dichloroaziridine were prepared from the imines insertion dichlorocarbene in a minimum of organic solvent conditions, using as catalyst KF/Al2O3 and yields higher than 98%. The gem-dichloroaziridines were converted to amides by hydrolysis in absence of solvent and yields higher than 98.0%. Within the concept of Green Chemistry were prepared six imines: N-benzyl- phenylmethanimine, N-phenyl-2- furylmethanimine, N-phenyl- phenylmethanimine, N-phenyl-(4-methoxyphenyl)methanimine, N-benzyl-(4-methoxyphenyl)metha-nimine,N-(2-furylmethyl)-2-furylmethanimine; two gem-dichloroaziridinas: 2,2-dichloro-1,3-diphenyla-ziridine and 1-benzyl-2,2-dichloro-3-phenylaziridine and two amides: chlorophenylacetanilide and N-benzyl-chloro-phenylacetamide.

No description available.

Thèse diffusée initialement dans le cadre d'un projet pilote des Presses de l'Université de Montréal/Centre d'édition numérique UdeM (1997-2008) avec l'autorisation de l'auteur.

This thesis is mainly focused on the reactions of oxo-pyrimidines and oxo-imidazoles with nitric acid in sulfuric acid and properties of the gem-dinitro products formed in this process. Low temperature nitrations of 2-methylimidazoles produced – in addition to the known 2-methyl-5(4)-nitroimidazole – 2-(dinitromethylene)-5,5-dinitro-4-imidazolidinone and parabanic acid. This tetranitro compound was also obtained via nitration of 2-methyl-4,4-dihydro-(1H)-5- imidazolone. Thermal decomposition of 2-(dinitromethylene)-5,5-dinitro-4-imidazolidinone yielded 2-(dinitromethylene)-4,5-imidazolidinedione, which also was the product from the nitration of the new compound 2-methoxy-2-methyl-4,5-imidazolidienedione. Treatment of 2- (dinitromethylene)-5,5-dinitro-4-imidazolidinone with aqueous ammonia resulted in the previously unknown 1,1-diamino-2,2-dinitroethylene (Paper I). The nitration of some 2-substituted pyrimidine-4,6-diones in sulfuric acid, which afforded previously unknown 5,5-gem-dinitro-pyrimidine-4,6-diones in high yields, was studied. Alloxane was prepared in a one-step procedure by thermal decomposition of 5,5-dinitrobarbituric acid in hot acetic acid. The gem-dinitro products were found to be easily attacked by nucleophiles with concomitant formation of gem-dinitroacetyl derivatives, which in turn could be further hydrolysed to salts of dinitromethane and triureas (Papers II and III). Nitration of 4,6-dihydroxypyrimidine in sulfuric acid yielded nitroform as the sole product. This behaviour was tentatively explained by the formation of an intermediate, 5,5-dinitro-4,6- dihydroxypyrimidine, which underwent hydrolysis in the nitrating acid into gem-dinitroacetyl formamidine. This compound was further nitrated in the same reaction mixture into trinitroacetylformamidine, which finally underwent hydrolytic cleavage into nitroform. It was also demonstrated that gem-dinitroacetylureas could produce nitroform upon nitration. The structures of the proposed trinitroacetylureas were confirmed by the isolation of one of their derivatives (Paper IV). / QC 20100907

The biological effects of charged particles is of interest in particle therapy, radiation protection and space radiation science and known to be dependent on both absorbed dose and radiation quality or LET. Microdosimetry is a technique which uses a tissue equivalent gas to simulate microscopic tissue sites of the order of cellular dimensions and the principles of gas ionization devices to measure deposited energy. The Gas Electron Multiplier (GEM) has been used since 1997 for tracking particles and for the determination of particle energy. In general, the GEM detector works in either tracking or energy deposition mode. The instrument proposed here is a combination of both, for the purpose of determining the energy deposition in simulated microscopic sites over the charged particle range and in particular at the end of the range where local energy deposition increases in the so‐called Bragg‐peak region. The detector is designed to track particles of various energies for 5 cm in one dimension, while providing the particle energy deposition every 0.5 cm of its track. The reconfiguration of the detector for different particle energies is very simple and achieved by adjusting the pressure of the gas inside the detector and resistor chain. In this manner, the detector can be used to study various ion beams and their dose distributions to tissues. Initial work is being carried out using an isotopic source of alpha particles and this thesis will describe the construction of the GEM‐based detector, computer modelling of the expected gas‐gain and performance of the device as well as comparisons with experimentally measured data of segmented energy deposition. / UOIT

Thèse diffusée initialement dans le cadre d'un projet pilote des Presses de l'Université de Montréal/Centre d'édition numérique UdeM (1997-2008) avec l'autorisation de l'auteur.

Diss.--Hamburg. / Bibliography: p. 195-201.

Diss.--Hamburg. / Bibliography: p. 195-201. Also issued online.

El presente trabajo aborda un procedimiento para la problemática de la determinación de la geometría y extensión de las zonas de fracturamiento inducido en un macizo rocoso de origen ígneo considerando los estados previo y posterior a la realización de tronaduras con el objeto de aumentar el fracturamiento del macizo. Lo anterior permite el aumento de la porosidad, mejorando así la conductividad hidráulica de la roca necesario para el proceso de Lixiviación In Situ Confinada (LISC). El interés principal es evaluar el efecto de la intervención con explosivos mediante un método no invasivo y determinar variables claves para la LISC como lo son la existencia de acuíferos y dispersividad de los fluidos inyectados, lo que permitiría evaluar de mejor manera los mejores sitios para la realización de LISC en una futura etapa de extracción de cobre a escala industrial en yacimientos marginales de CODELCO-Chile como lo es la División El Salvador, lugar donde se realizó el estudio. Con el fin de elaborar la caracterización geofísica del macizo rocoso se realizaron mediciones de resistividad eléctrica mediante un método electromagnético de alta frecuencia usando el instrumento GEM-2 que genera un campo electromagnético primario, compuesto por la suma de campos sinusoidales a distintas frecuencias entre los 300[Hz] y 47[kHz]. Este campo magnético primario induce corrientes de Focault en el terreno que generan un campo secundario, que a su vez es medido por el instrumento. Con la información de los campos primario y secundario se procede a determinar los valores de conductividad aparente (σa) y susceptibilidad aparente (χa) del subsuelo para cada frecuencia y punto de medición. Para la determinación de la profundidad de medición se propone la utilización de la profundidad referencial que se define a partir de la idea del centroide de la capa en un modelo de tierra estratificada por capas horizontales y que se basa en la determinación del skin depth. Debido al ruido de alta frecuencia existente en los datos se procedió a realizar un filtrado pasabajos con un filtro gaussiano de longitud de onda de corte igual a 5[m] de los datos de línea, luego se procedió a realizar un filtrado de los datos en planta por medio de un filtro gaussiano pasabajos 2D con la misma longitud de onda de corte que el filtro de datos en línea, lo que permite eliminar los lineamientos ocacionados por la interpolación. Con los resultados de conductividad y profundidad se pudieron realizar modelos de conductividad en 3D de las celdas de prueba para cada uno de los registros realizados. Los modelos 3D de conductividad permiten caracterizar las zonas estudiadas hasta una profundidad de aproximadamente 40[m] en promedio. Entre los aportes del presente trabajo se puede destacar la caracterización exitosa de la geometría de las zonas fracturadas, la identificación de las zonas preferenciales del desplazamiento de fluidos y la evaluación del efecto del uso de los explosivos, que pueden considerarse metodologías válidas para zonas de baja conductividad hidráulica. Sin embargo el mayor aporte lo constituye el hecho de proponer una metodología para el tratamiento de datos en el método de prospección electromagnética, que puede ser extrapolable para su uso en cualquier problema geofísico atingente.

No description available.