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Bílková, Karolina. "Benzen v benzinech z hlediska ochrany zdraví." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2008. http://www.nusl.cz/ntk/nusl-216417.
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Benzene is very toxic compound, which has carcinogenic and mutagenic effects. Result of these effects is significant reduction of its use and also low hygienic limits in occupational environment and environment. The aim of this diploma thesis was to map out possible exposure to benzene and checking of clasification correctness of motor gasoline and benzine (cleaners, thinners etc.). Determination of benzene was carried out by gas chromatography with flame ionisation detector (GC/FID) and high performance liquid chromatography with diod array detector (HPLC/DAD). Marginally, the diploma thesis was focused on determination of toluene (in june 2007 became effective ordinance no.284/2006 Sb., which forbid to sell products that contain more than 0,1 % of toluene to small consumers). Toluene was determined by same methods as benzene.
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Kim, Kimyoung. "Biodegration of Benzene." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/101184.
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This study was conducted to estimate the kinetic constants of benzene-acclimated biomass at optimum conditions and investigate the effectiveness of soil inoculation to expedite the biodegradation of benzene. A complete-mix, bench-scale, continuous-flow, activated-sludge reactor was used to develop organisms capable of utilizing benzene as a sole carbon and energy source. Settled pond water was used as seeding inocula and about 2000 mg/I of MLSS was maintained at the steady state with the MCRT of 7 days. The culture was used to inoculate the experimental bottle equipped with a sampling port. A series of different initial concentrations of benzene were established in the bottles for the batch growth tests. Samples were drawn every hour and the optical densities were measured at 540 nm in order to assess the growth rate. A nonlinear least-squares regression technique was employed to estimate the constants of the Haldane equation (an inhibition function). µm was 0.31 hr⁻¹, K₂ was 1.36 mg/I and Ki, was 1.50x10¹⁵' mg/I in the range of 14 - 491 mg/I of benzene. A small amount of the acclimated bacteria was added to the normal moist subsoil containing 100 mg/I of benzene and enough mineral nutrients. The soils were put in septum-capped glass bottles and incubated in the dark for a month. The benzene concentration in the autoclaved bottles did not decrease during the incubation period while that in the inoculated bottles was reduced to zero within 4 days and that in the uninoculated bottles was reduced to zero within 13 days.M.S.
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Barnes, Martine Luan. "Thiol chemistry of benzene oxide and muconaldehydes pertinent to benzene toxicology." Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324825.
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Bratton, Shawn Brian. "Benzene-derived quinol-thioethers induce apoptosis in hematopoietic tissue via a unique ceramide signaling pathway /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Aburto, Arturo. "Microbial diversity and factors affecting benzene degradation in a benzene-contaminated aquifer." Thesis, University of Essex, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435557.
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Zonetti, Priscila da Costa. "Hidrogenação parcial do benzeno com catalisadores de Ru/CeO2 : efeitos do tratamento termico." [s.n.], 2003. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267451.
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Orientador: Antonio Jose Gomez CoboDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: O presente trabalho tem como principal objetivo estudar a influência das condições de ativação (calcinação e redução) sobre o desempenho de catalisadores Ru/Ce02, destinados à reação de hidrogenação parcial do benzeno para a obtenção de cicloexeno. Para tanto, catalisadores de RulCe02 foram preparados pelo método da impregnação a seco, partindo-se de uma solução aquosa do precursor metálico RuCl3/xH20. Após a impregnação, os sólidos foram secos a 358K, por um período aproximadamente de 24 h. A seguir, os catalisadores foram submetidos aos tratamentos de calcinação em atmosfera de ar nas temperaturas de 473K e 673K, e/ou reduzidos em atmosfera de H2 nas temperaturas de 523K, 773K e 1023K. Os sólidos obtidos foram caracterizados por meio das técnicas de análise termogravimétrica, medida de área superficial específica (método B.E.T.), difração de raios X, quimissorção de O2, RTP e XPS. O desempenho dos catalisadores foi avaliado na reação de hidrogenação do benzeno, empregando-se um reator trifásico do tipo leito de lama ("slurry"). A reação foi conduzida sob pressão constante de 5,0 MPa de H2 e à temperatura de 373K, em meio reacional trifásico, contendo água e o aditivo TiC3. Os perfis de TPR dos catalisadores preparados sugerem que uma oxidação profunda do Ru é induzida pelo tratamento de calcinação. Os resultados das análises de XPS confirmam tal suposição, mostrando que o rutênio se encontra na forma de RU02 na amostra calcinada a 673K, enquanto que no sólido reduzido a 773K tem-se Ru no estado metálico. No entanto, a etapa de calcinação, seguida ou não de redução, é fortemente prejudicial ao desempenho catalítico, provavelmente devido à forte oxidação do rutênio, a qual pode ser promovida pelo suporte Ce02. Por sua vez, a redução direta conduz a catalisadores RulCe02 mais ativos, bem como a maiores rendimentos em cicloexeno, ao longo de toda a reação
Abstract: The aim of the present work is to study the influence of the activation conditions (calcination and reduction) on the performance of Ru/CeO2 catalysts, to the benzene partial hydrogenation reaction for cyc1ohexene production. Therefore, Ru/CeO2 catalysts were prepared by incipient wetness impregnation method, through an aquous solution of the RuChxH20 metallic precursor. After the impregnation, the solids were dried at 358K, for a period of 24h. To follow, the catalysts were submitted to the treatments of calcination in air atmosphere at the temperatures of 473K and 673K and/or reduction in H2 atmosphere at the temperatures of 523K, 773K and 1023K. The solids obtained were characterized by means of termogravimetric analysis, measure ofn specific superficial area (BET method), x-ray diffraction, oxygen chemisorption, RTP and XPS techniques. The performance of the catalysts was evaluated in the benzene hydrogenation reaction, with a slurry three-phase reactor. The reaction was lead under constant H2 pressure of 5,OMPa at the temperature of 373K, in a three-phase reactional medium with water and TiCl3 additive. RTP profiles of the prepared catalysts suggest that a deep oxidation of the Ru is induced for the ca1cination treatment. The results of the XPS analyses confirm such assuption, showing that in the ca1cinated sample at 673K the ruthenium form is RUO2, while in the solid reduced at 773K there is Ru in its metallic state. Howerer, the ca1cination step, followed or not of reduction, is strongly harmful to the catalytic perfomance. That is probably due to strong oxidation of the ruthenium, which can be promoted by the CeO2 support. In turn, the direct reduction leads to Ru/CeO2 catalysts more actives, as well as to higher yields of cyc1ohexene, throughout all the reaction
Mestrado
Sistemas de Processos Quimicos e Informatica
Mestre em Engenharia Química
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Rodrigues, Michelle Fernanda Faita. "Hidrogenação parcial do benzeno em fase liquida : influencia da natureza e da morfologia dos suportes alumina e niobia no desempenho de catalisadores de rutenio." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266248.
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Orientador: Antonio Jose Gomez CoboDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: No presente trabalho, tem-se por objetivo estudar os efeitos da morfologia do suporte, notadamente do diâmetro da partícula e da área específica, sobre o desempenho de catalisadores de Ru/Al2O3 e Ru/Nb2O5 destinados à reação de hidrogenação parcial do benzeno em fase líquida. Para tanto, catalisadores de Ru/Al2O3 e Ru/Nb2O5 foram preparados através de impregnação incipiente, a partir de uma solução aquosa do precursor RuCl3.xH2O, empregando-se os respectivos suportes com granulometrias e áreas específicas diversas. Após impregnação, os sólidos foram secos a 358 K, por um período de cerca de 24 h. A seguir, os sólidos foram submetidos a um tratamento de redução direta sob H2, à temperatura de 573 K. Os sólidos obtidos foram caracterizados através das técnicas Mastersizer-Distribuição do Tamanho de Partícula, Difração de Raios-X, Adsorção de N2 (método B.E.T.), Microscopia Eletrônica de Varredura com Microssonda para Análise Espectrométrica de Raios-X e Redução à Temperatura Programada. Os desempenhos catalíticos foram avaliados na reação de hidrogenação do benzeno, empregando-se um reator Parr do tipo ¿slurry¿. A reação foi conduzida sob pressão constante de 5,0 MPa de H2 e à temperatura de 373 K, em meio reacional trifásico contendo água. Para as condições empregadas neste estudo, os resultados obtidos mostram que praticamente não há influência da natureza dos suportes Al2O3 e Nb2O5 sobre a seletividade de cicloexeno. No entanto, o aumento do diâmetro de partícula ou da área específica do suporte diminui o rendimento do produto desejado
Abstract: The principal aim of the present work is to study the effects of the morphology of supports, especially the particle diameter and the specific area on the performance of catalytic Ru/Al2O3 and Ru/Nb2O5 for partial hydrogenation reaction of benzene in liquid phase. Therefore, Ru/Al2O3 and Ru/Nb2O5 catalysts were prepared by incipient wetness impregnation, from an aqueous solution of RuCl3.xH2O chlorinated precursor, using supports with several granulometries and specific areas. After impregnation, the solids were dried at 358 K, for a period of 24 h. Then the solid underwent a treatment to direct reduce under H2, at the temperature of 573 K. The solid results were characterized by technical Mastersizer-Particle size Analysis, Diffraction of X-rays, adsorption of N2 (BET method), Electronic Scanning Microscopy and Temperature Programmed Reduction (TPR). The performances were evaluated in the catalytic reaction of benzene hydrogenation, using a reactor Parr of the "slurry". The reaction was conducted under constant pressure of 5.0 MPa of H2 and a temperature of 373 K, in a three-phase reactional medium with water. For the conditions employed in this study, the results show that virtually no influence the nature of the Al2O3 and Nb2O5 supports on the ciclohexene selectivity. However, the increase in the diameter of particle or the specific area of support decreases the yield of the desired product
Mestrado
Sistemas de Processos Quimicos e Informatica
Mestre em Engenharia Química
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Abussaud, Basim Ahmed. "Wet air oxidation of benzene." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103362.
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Processing of petrochemical compounds produces a large amount of wastewater. This wastewater consists of toxic (hazardous) materials that can not be discharged to the environment without treatment. As restrictive environmental constraints increase, new technologies are needed to treat those toxic materials before discharging them to the environment. Wet Air Oxidation (WAO) is one of these new methods.This study casts light on the effect of initial pH on the WAO of benzene at different temperatures and pressures. It was found that at pH 6, a temperature of 260°C and a partial pressure of oxygen of 1.38 MPa around 97% degradation was achieved in one hour. When the initial pH was lowered to 4 more than 90% degradation was achieved at 220°C and PO2 of 1.38 MPa in only 15 minutes.` It was concluded that the higher the temperature the better the benzene degradation, and the faster benzene degradation has been obtained with the increasing partial pressure of oxygen. The main intermediates were acetic acid and formic acid.
Furthermore, it was found that the degradation of benzene can be further enhanced in the presence of phenol. The main reason can be attributed to the effect of the free radicals generated from the fast phenol degradation. A simplified pathway for oxidation of benzene was proposed.
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Andrejeva, Anna. "Spectroscopy of substituted benzene molecules." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/34936/.
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Consistent assignment of vibrational motions across substituted benzene derivatives is a long-standing desire amongst spectroscopists. In this thesis, the S1 electronic states of monohalosubstituted benzene molecules and their deuterated isotopologues are investigated, using resonance enhanced multiphoton ionisation spectroscopy. The observed vibrational bands are assigned using the Mi nomenclature proposed by Gardner and Wright where ring localised vibrations having the same atomic motion are given the same label, allowing straightforward comparisons of vibrational motions across monosubstituted benzene molecules to be achieved. Detailed investigation showed that it would not be possible to apply the same Mi nomenclature labels to the para disubstutited benzene derivatives owing to the different vibrational motions of mono- and disubstituted benzene molecules. As a consequence a new nomenclature, Di, for labelling the vibrational motions of para disubstituted benzene molecules is proposed in this work. The Di labelling scheme is based on the vibrations of the para difluorobenzene molecule. S0 state vibrations of symmetric and asymmetric para dihalobenzene species, para fluorotoluene and para xylene are studied in detail, showing that the ring localised vibrational motions of para disubstituted benzene species are being described by the same label.
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Santos, Deodato Peixoto dos. "Determinação eletroquímica de fenóis após processo de degradação de benzeno usando sensor à base de nanotubos de carbono-ftalocianina de cobalto." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/75/75135/tde-17042012-164903/.
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Episódios de contaminação envolvendo hidrocarbonetos de petróleo são relatados com bastante freqüência, principalmente em função dos acidentes envolvendo transporte e estocagem de combustíveis, dentre os quais se destacam o benzeno, tolueno, etilbenzeno e xileno (BTEX). Assim, não é surpreendente o grande número de trabalhos, atualmente disponíveis, relacionados à remediação de águas subterrâneas. Entretanto, é conhecido que a total mineralização de benzeno, na maioria das tecnologias utilizadas para remediação de solos e águas subterrâneas, não ocorre totalmente podendo formar compostos fenólicos altamente tóxicos. Por este motivo, este trabalho teve por finalidade a análise dos subprodutos formados a partir da degradação do benzeno, que são eles: hidroquinona, resorcinol, catecol, fenol, p-benzoquinona. Para este propósito, os compostos fenólicos formados foram medidos utilizando um eletrodo de carbono vítreo modificado com filme de nanotubos de carbono e ftalocianinas metalicas. Os compostos fenólicos também foram analisados por cromatografia liquida de alta eficiência com detector espectrofotométrico, espectrometria no UV/Visível. Os sensores eletroquímicos propostos mostraram-se altamente eletrocatalíticos e sensíveis na determinação dos derivados da oxidação do benzeno, obtendo-se um limite de detecção de 4,54 μmol L-1 para a hidroquinona, de 1,63 μmol L-1 para o resorcinol, 0,14 μmol L-1 para o catecol, 4,19 μmol L-1 para o fenol e 1,78 μmol L-1 para a p-benzoquinona. Observa-se que existem algumas diferenças nos limites de detecção para cada composto fenólico estudado e que o eletrodo GC/MWCNT/CoPc apresentou menores limites de detecção para o catecol, resorcinol e p-benzoquinona podendo analisar predominantemente esses compostos fenólicos a partir da eletro-oxidação do benzeno. A metodologia proposta comparada com os métodos oficiais de análise e foi observado que os sensores atingem os limites mínimos necessários de detecção, demonstrando que sensores eletroquímicos baseados em CNTs tornam-se uma alternativa no desenvolvimento de metodologias altamente sensíveis, rápidas e de baixo custo.Contamination episodes involving petroleum hydrocarbons are reported quite frequently, mainly because of accidents involving transportation and storage of fuels, among which stand out as benzene, toluene, ethylbenzene and xylene (BTEX). Thus, it is not surprising the large number of papers currently available relating to remediation of groundwater. However, it is known that the complete mineralization of benzene, most of the technologies used for remediation of soil and groundwater, it doesn\'t occur and it can form highly toxic phenolic compounds. For this reason, this paper aims to analyze the products formed from the degradation of benzene, which are: hydroquinone, resorcinol, catechol, phenol, p-benzoquinone. For this purpose, the phenolic compounds formed were measured using a glassy carbon electrode modified with a film of carbon nanotubes and metallic phthalocyanines. Phenolic compounds were also analyzed by high performance liquid chromatography with UV detection, spectroscopy in UV / Visible. The proposed electrochemical sensors were highly sensitive and the electrocatalytic determination of the oxidation of benzene derivatives, obtaining a detection limit of 4.54 μmol L-1 for hydroquinone, 1.63 μmol L-1 for resorcinol , 0.14 μmol L-1 for catechol, 4.19 μmol L-1 for phenol and 1.78 μmol L-1 for p-benzoquinone. It is observed that there are some differences in detection limits for each phenolic compound studied and the electrode GC/MWCNT/CoPc had lower detection limits for catechol, resorcinol and p-benzoquinone can analyze these phenolic compounds predominantly from the electro- oxidation of benzene. The proposed methodology was compared with the official methods of analysis and it was observed that the sensors reach the required minimum limits of detection, demonstrating that electrochemical sensors based on CNTs become an alternative for the development of high sensitivity, rapid and low-cost. methodologies.
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Iimori, Toshifumi. "Laser Spectroscopic Study of Benzene Clusters." 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/150401.
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Jiménez, Cristina. "1,2-bis-(ditertbutylphosphinomethyl)benzene in catalysis." Thesis, University of St Andrews, 2004. http://hdl.handle.net/10023/2650.
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Different diphosphine ligands having the structure shown below have been studied for carbonylation and hydroformylation reactions. Depending on the substituent on the phosphorus atoms the electronic and steric properties can be tuned to direct the reaction towards the desired products. Palladium methoxycarbonylation of a large variety of unsaturated compounds has been attempted under very different conditions. The outcome of these reactions was the achievement of the linear products with a selectivity higher than 99.5 % under mild conditions of pressure and temperature. Chloroaromatic compounds have also been employed as substrates in methoxycarbonylation reactions. Unexpected results were observed since carbonylation was possible only when a strong electron withdrawing group was present. The origin of the many side products from these reactions has been elucidated. Rhodium hydroformylation was not as successful as palladium Methoxycarbonylation since relatively severe conditions had to be used to get good rates and good selectivity. In no case were there as good as those obtained in the carbonylation reactions. However, unusual factors, such as the presence of chlorine in the reaction media, have been found to influence either the conversion or the selectivity.
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Sayyar, Mohammad H. "Direct oxidation of benzene to phenol." Thesis, Loughborough University, 2008. https://dspace.lboro.ac.uk/2134/15135.
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This thesis deals with two major process routes for the direct oxidation of benzene to phenol. The main objective of the first route was to understand the properties of the porous stainless steel (PSS) needed for support of a catalyst deposited onto its surface, to identify the morphologies of the Pd membrane deposited onto the PSS, to design a catalytic membrane reactor, to characterise membrane in terms of its permeability to hydrogen, and then to investigate hydroxylation of benzene using oxygen as an oxidant. It was observed, using Mo or zeolites as a second catalyst and the reactor design affect the productivity and selectivity towards phenol. This research has also shown the effects of the catalytic properties of iron zeolites with a focus on reactions involving the decomposition of nitrous oxide and direct oxidation of benzene to phenol using nitrous oxide as the oxidant. The main objective of this second route was to identify the active sites in the catalysts, and to a design catalyst based on the acquired knowledge. The methodology was to incorporate iron either at framework positions via hydrothermal synthesis of the zeolites followed by controlled migration to extra-framework positions, or directly at extra-framework positions via sublimation of FeCh or liquid ion-exchange. In this project, different catalysts were characterized and their catalytic activities compared. It was observed contaminants such as N-containing compounds, O2, CO, and water affected the catalytic properties and catalyst half-life. In this thesis, two different methods were used to improve productivity when using a PdlPSS membrane. First, changing design of the reactor, and second, using Mo as a second catalyst. It was observed that higher productivity was obtained when the reactor tube was packed with Fe/ZSM-5 and N20 using as the oxidant. From an economic point of view, using N20 in the presence of zeolite in a fixed-bed reactor is expected to offer more advantages than Pd membrane for oxidation of aromatic compounds.
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McCloskey, Colleen B. "Biodegradation of benzene in soil systems." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-01312009-063028/.
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Houot, Jennifer. "Pollution de l'air, trafic routier, et risque de leucémie chez l'enfant." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS108/document.
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La cancérogénicité du benzène à forte dose (CIRC, Groupe 1) a été démontrée sur la base des cas de leucémies observés dans les études épidémiologiques conduites en milieu professionnel chez l’adulte exposé à de fortes doses. Ce polluant est émis en faible concentration dans l’environnement, notamment par le trafic routier et les stations-service. L’objectif est d’étudier le lien entre exposition au benzène à faible dose et risque de leucémie chez l’enfant. L’étude GEOCAP regroupe les cas de leucémies de l’enfant diagnostiqués en France entre 2002 et 2007 issus du Registre National des Hémopathies de l’Enfant, et un échantillon de 30 000 témoins représentatif de la population générale pédiatrique. La longueur de routes à fort trafic a été calculée au voisinage de la résidence de chaque sujet géocodé dans un rayon de 150 m. Les concentrations en benzène et en NO2 ont été estimées pour l’ensemble des sujets de France continentale à une échelle de 2 km2. La distance à la station-service la plus proche a également été calculée depuis la résidence de chaque sujet. La longueur de routes au voisinage de la résidence était positivement et significativement associée au risque de leucémie aigüe myéloblastique (LAM). La prise en compte des expositions au benzène et en NO2 renforçait cette association. La distance à la station-service la plus proche était positivement mais non-significativement associée à la LAM, et cette association résultait en partie d’un effet de confusion de la longueur de routes au voisinage de la résidence. Ce travail soutient l’hypothèse selon laquelle l’exposition au benzène émis dans l’environnement pourrait induire une augmentation du risque de LAM chez l’enfantIn adults, the relationship between benzene exposure (IARC, Group 1) and leukemia has been demonstrated in workplace for high-level exposure. This pollutant is emitted at low concentration in environment, especially by road traffic and petrol stations. The objective was to investigate the relationship between benzene exposure at low-level dose and childhood leukemia. The record-based GEOCAP study included all cases of childhood leukemia diagnosed in France over 2002-2007 and 30,000 contemporaneous population-based control children highly representative of the source population. The length of major roads was calculated around the residence of each geocoded subject in a 150-m buffer. We assigned them the yearly estimates of benzene and NO2 concentrations at the square where his residence was located on a 2-km2 grid covering continental France. The distance to the nearest petrol station from the residence was also calculated for all subjects. The length of major roads around the residence was positively and significantly associated with the risk of acute myeloblastic leukemia (AML). This association was more evident with benzene and NO2 2-km estimates, combined with the length of major roads indicator to enhance the exposure contrasts. The distance to the nearest petrol station was positively but non-significantely associated with AML, and some of this association was explained by a confouding effect of the length of major roads around the residence. This work suggests that exposure to benzene emitted in environment may increase the risk of AML in children
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Zanutelo, Cristiane 1976. "Influencia do tratamento aplicado ao suporte sobre o desempenho de catalisadores de RU/C para a hidrogenação parcial do benzeno em fase liquida." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267095.
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Orientadores: Antonio Jose Gomez Cobo, Wagner Alves CarvalhoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: A hidrogenação parcial do benzeno é uma reação química de interesse industrial, uma vez que o cicloexeno obtido pode ser empregado para a produção de diversos produtos. Além disso, ainda encontra uma importante aplicação na proteção ambiental, face às severas restrições à presença de compostos aromáticos nos combustíveis. O presente trabalho tem o objetivo de estudar a influência do tratamento aplicado ao suporte no desempenho de catalisadores de Ru sobre carvão ativado, destinados à reação de hidrogenação parcial do benzeno em fase líquida. Para tanto, um carvão ativado comercial foi submetido a diferentes tratamentos físicos e/ou químicos. Os sólidos obtidos foram empregados como suporte na preparação de catalisadores 5 % Ru/C. Os catalisadores foram preparados através de impregnação à seco, partindo-se de uma solução aquosa do precursor RuCl3.xH2O. Após impregnação, alguns catalisadores foram submetidos a uma redução direta sob H2, à temperatura de 423 K, com o intuito de avaliar os efeitos de tal tratamento de ativação. Os suportes preparados foram caracterizados através da adsorção de N2 (método de B.E.T.), titulação de Boehm, titulação potenciométrica e da determinação da entalpia de imersão em água. A espectroscopia de fotoelétrons excitados por raios X foi utilizada para estudar a superfície de suportes e catalisadores, enquanto que a microscopia eletrônica de varredura possibilitou determinar a composição química e observar a morfologia dos catalisadores. O desempenho dos catalisadores de Ru/C foi avaliado na reação de hidrogenação do benzeno em fase líquida, empregando-se um reator Parr do tipo "slurry". A reação foi conduzida sob pressão total de 5,0 MPa de H2, à temperatura de 373 K e com a presença de água no meio reacional. Os resultados obtidos indicam que o desempenho catalítico do sistema Ru/C é influenciado por determinados grupos funcionais presentes na superfície do carvão ativado. Os grupos carbonila diminuem a atividade e a seletividade da reação, enquanto que um aumento dos grupos carboxílicos conduz a catalisadores mais ativos e a maiores rendimentos em cicloexeno.
Abstract: The partial hydrogenation of benzene is a chemical reaction of industrial interest, as the cyclohexene obtained may be used to production of several products. Moreover, it also finds important application in the ambient protection, face to the severe restrictions to the aromatical composite presence in fuels. The aim of the present work is to study the influence of the treatment applicated the support on the performance of Ru catalysts on activated charcoal, to the benzene partial hydrogenation reaction in liquid phase. Therefore, commercial activated charcoal was submitted by means of different physical and/or chemical treatments. The solids obtained were used as support to the preparation of 5 wt.% Ru/C catalysts. The catalysts were prepared by incipient wetness impregnation method, through an aqueous solution of the precursor RuCl3.xH2O. After impregnation, some catalysts were submitted a direct reduction in H2 atmosphere at the temperature of 423 K, in order to evaluate the effects of such treatment of activation. The supports prepared were characterized by N2 adsorption (B.E.T. method), Boehm's titration, potenciometric titration and determination of the enthalpy of immersion in water techniques. The X-ray photoelectron spectroscopy technique was used to study the surface of supports and catalysts, whereas the electronic scanning microscopy allowed to determine the chemical composition and observe the morphology of the catalysts. The performance of the Ru/C catalysts was evaluated in the benzene hydrogenation reaction, using a Parr reactor of type "slurry". The reaction was conducted under total pressure of 5,0 MPa of H2 at a temperature of 373 K, with the presence of water in reactional medium. The results obtained indicate that the catalytic performance of the system Ru/C is influenced for determined functional groups present on the surface of activated charcoal. The carbonyl groups decrease the activity and selectivity of the reaction, while an increase of the carboxylic groups leads to more active catalysts and the highest yield of cyclohexene.
Mestrado
Sistemas de Processos Quimicos e Informatica
Mestre em Engenharia Química
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Suppino, Raphael Soeiro 1984. "Hidrogenação parcial do benzeno com catalisadores de Ru/A12O3 e Ru/CeO2 = efeitos do metodo de impregnação e da adição de solventes ao meio reacional em fase liquida." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266945.
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Orientador: Antonio Jose Gomez CoboDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: A reação de hidrogenação parcial do benzeno em fase líquida tem sido estudada com vistas à obtenção do cicloexeno. Este produto de alto valor agregado pode ser utilizado para a obtenção de poliamidas, como o nylon, através de uma rota industrialmente simples e ecologicamente correta. Esta reação possui ainda uma importante aplicação na proteção ambiental, face às severas restrições à presença de compostos aromáticos nos combustíveis. O presente trabalho tem por objetivo estudar o desempenho de catalisadores de Ru/Al2O3 e Ru/CeO2 preparados através dos métodos de impregnação incipiente e impregnação úmida. Objetiva-se ainda estudar os efeitos da adição de solventes orgânicos ao meio reacional, e a utilização dos solventes na separação dos produtos da reação. Os catalisadores estudados foram preparados a partir de soluções aquosas de RuCl3.xH2O. No caso da impregnação incipiente, os sólidos foram secos a 358 K por 24 h e reduzidos sob fluxo de H2 a 573 K por 3 h. No caso da impregnação úmida, os catalisadores foram reduzidos com formaldeído a 353 K, durante a impregnação. Os suportes Al2O3 e CeO2 foram caracterizados através de titulação potenciométrica e a adsorção de N2 (método de B.E.T.) foi empregada para determinar a área específica dos sólidos. As técnicas de MEV+EDX e XPS permitiram avaliar a composição dos sólidos, enquanto que a formação da fase ativa dos catalisadores foi estudada através de TPR. O desempenho dos catalisadores foi avaliado na reação de hidrogenação parcial do benzeno em fase líquida, conduzida à pressão constante de 5 MPa de H2 e a 373 K num reator Parr do tipo slurry. A destilação extrativa dos produtos de reação foi estudada com o software Aspen Plus®. Os resultados obtidos indicam que os catalisadores de Ru/Al2O3, preparados por impregnação úmida, apresentam os melhores desempenhos catalíticos nesta reação. O rendimento de cicloexeno aumenta com a adição de solvente ao meio reacional, segundo a ordem: monoetanolamina > monoetilenoglicol > n-metil-2-pirrolidona > acetato de etila. Nas condições deste estudo o monoetilenoglicol foi o único solvente capaz de separar todos os produtos de reação com eficiência suficiente para um processo industrial
Abstract: The reaction of partial hydrogenation of benzene in liquid phase has been studied with the purpose of obtaining cyclohexene. This product of high aggregated value can be used to obtain polyamides such as nylon, through a route industrially simple and environmentally friendly. This reaction also has an important application in environmental protection, given the severe restrictions on the presence of aromatics in fuels. In this context, this work aims to study the performance of Ru/Al2O3 and Ru/CeO2 catalysts prepared by the methods of incipient impregnation and wet impregnation. Another object of the present work is to study the effects of adding organic solvents to the reaction medium, and the use of these solvents for the separation of reaction products. The catalysts were prepared from aqueous solutions of RuCl3. xH2O. In the case of incipient impregnation, the solids were dried at 358 K for 24 h and reduced under H2 flow at 573 K for 3 h. In the case of wet impregnation, the catalysts were reduced with formaldehyde at 353 K during the impregnation step. The supports Al2O3 and CeO2 were characterized by potentiometric titration and N2 adsorption (B.E.T. method) was used to determine the specific area of the solids. The techniques of SEM + EDX and XPS allowed the evaluation of the composition of solids, whereas the formation of the active phase of catalysts was studied by TPR. The performance of the catalysts was evaluated in the liquidphase partial hydrogenation of benzene carried out at H2 constant pressure of 5 MPa and 373 K in a slurry Parr reactor. The extractive distillation of the reaction products was studied with the software Aspen Plus ®. The results indicate that the catalysts Ru/Al2O3, prepared by wet impregnation, led to the best performances observed for this reaction. The yield of cyclohexene increases with the addition of solvent to the reaction medium, following the order: monoethanolamine > monoethylene glycol > n-methyl-2-pyrrolidone > ethyl acetate. In this study, monoethylene glycol was the only solvent able to efficiently separate all reaction products to obtain cyclohexene in an industrial process
Mestrado
Sistemas de Processos Quimicos e Informatica
Mestre em Engenharia Química
18
Al-Khulaifi, Nabeel. "Benzene exposure from automobiles fuelled with petrol." Thesis, University of Newcastle upon Tyne, 2002. http://hdl.handle.net/10443/3099.
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Benzene is a leukaemogenic and mutagenic agent, which may pose a risk to the general public even at low levels of exposure. Since petrol fuel contains a high concentration (1-5%) of benzene, there is the potential for exposure to man during car journeys. The main aim of this study was to develop and validate a sensitive method to detect urinary t,t-muconic acid (uMA) following low level environmental exposures to benzene. Subjects potentially exposed to benzene were divided into petrol (n= 9) and diesel groups (n= 7). The control group (n=14) consisted of individuals who were not exposed to benzene inside the car. The uMA method developed during this study involved butanol extraction instead of the traditional solid phase extraction followed by DV (259nm) detection. The method was reasonably precise (CV=1.5%) with >80% recovery from urIne. Air samples were collected on charcoal tubes and analysed for benzene, toluene, ethylbenzene, and xylenes by GCMS following extraction with purified carbon disulphide. The benzene concentration of ambient air samples taken from inside the cabins of petrol fuelled cars (7.5 ppb) was about triple that found from diesel-fuelled cars (2.6 ppb)(P=O.Ol). The uMA of volunteers exposed to petrol increased (p<0.01) post-sample in compared to pre-exposure level (0.66mgMA/gCr and 0.38mgMA/gCr, respectively). There was no increase in uMA for volunteers exposed to diesel. The uMA level of samples collected from individuals 2h-7h after exposure to petrol showed a significant association with the air benzene (p=0.012) and toluene (p=0.042) concentrations taken inside the car cabins. Half of the 24h-profiles of individuals exposed to petrol had at least one urine with 1 mgMA/gCr or higher, while all of the profiles of controls were below 1 mgMA/gCr. The technique developed in this study for the determination uMA showed promise as a tool for monitoring levels of benzene arising from low-level environmental exposures to petrol.
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Kankam, Kofi. "Alkylation of Benzene on Immobilized Phosphotungstic Acid." Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/etd/3847.
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Linear alkylbenzenes (LAB) are key intermediates in the synthesis of linear alkylbenzene sulfonate surfactants that are used in the manufacture of detergents. Production of LAB with traditional Lewis acids as catalysts, such as hydrofluoric acid, results in the formation of large amounts of toxic wastes and corrosion of industrial equipment. Phosphotungstic acid (PTA) has gained much attention in recent years as a solid catalyst for various alkylation reactions. This research work aims to develop a novel material based on PTA-containing silica gel, which can effectively catalyze LAB synthesis. Sol-gel synthesis of silica gel in the presence of PTA and tetraethyl orthosilicate as precursors produced a mesoporous aterial containing covalently embedded PTA clusters. Obtained superacidic catalyst demonstrated high catalytic activity in liquid-phase alkylation of benzene by various alkenes. Covalent embedding of catalytically active HPA clusters prevents their leaching from the catalyst surface, which enabled its excellent catalytic properties.
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Burnam, Sarah R. "The effect of ethanol cosolvency on benzene /." Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1456296021&sid=9&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Bennett, Kathryn C. (Kathryn Condreay). "Desorption/Diffusion of Benzene After Simulated Ground Water Remediation." Thesis, University of North Texas, 1989. https://digital.library.unt.edu/ark:/67531/metadc500458/.
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A study was undertaken to examine the desorption/ iffusion of benzene after simulated ground water remediation in aquifer material of differing carbon content using column experiments and comparing the results to batch experiments and adsorption empirical relationships. It was hypothesized that the organic carbon of the aquifer material will affect desorption/diffusion. Results from the column experiment indicated no significant difference in the increase benzene concentrations after remediation between aquifer materials of differing carbon content, however, a significant increase in benzene concentration was observed for all aquifer material. Fair agreement of retardation factors was observed between empirical relationships and batch and column experiments. However, the desorption phase of the batch experiment showed hysteresis and seemed to differ from the column experiment.
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Horton, Anthony Michael. "Non-industrial personal benzene exposure in a mediterranean climate /." Access via Murdoch University Digital Theses Project, 2007. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20070830.143310.
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Rautenbach, Daniel. "The development of an electrochemical process for the production of para-substituted di-hydroxy benzenes." Thesis, Nelson Mandela Metropolitan University, 2005. http://hdl.handle.net/10948/159.
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The project was concerned with the investigation of the electrochemical oxidation of various phenols, and to develop a viable reaction system for the production of the respective hydroquinones. Current production routes utilizing phenol as starting material have the limitations of using large amounts of acids, having to be stopped at low conversions and producing a mixture of the hydroquinones and catechols. Of the possible routes to the respective hydroquinones from the various phenols, the electrochemical oxidation of these phenols offers commercial and environmental advantages and hence formed the theme of the investigation. The synthetic possibilities proved to be more prevalent in a system when the electrochemical oxidation of these phenols was performed in an aqueous medium utilizing an organic co-solvent. Results obtained during this investigation made it possible to make certain predications about the mechanism taking place. This was found to depend on the anode material used for the oxidation. The results showed that the process developed for the electrochemical oxidation of these phenols, yields mainly the para-isomers of the respective hydroquinones and benzoquinones in good yields and selectivities, with fair current efficiencies and good mass balances at high conversions. For example: * Phenol (batch) 8 F: 345% current efficiency, 70% hydroquinone, 6% catechol, 9% benzoquinone, 9% phenol and 94 mass balance. * 2-Tert-butylphenol (flow) 10 F: 37% current efficiency, 65% hydroquinone, 33% benzoquinone, 2% phenol and 100% mass balance. * 2,6-Di-tert-butylphenol (flow) 11 F: 23% current efficiency, 92 % hydroquinone, 6% benzoquinone, 1% phenol and 99% mass balance. The developed electrochemical oxidation system offers the following advantages over previous and current methods: simplified isolation and extraction procedures, smaller amounts of acid usage, reasonably selective synthesis of the para-isomer and a less corrosive system all at high conversions.
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Guti??rrez, Jos?? Antonio School of Microbiology & Immunology UNSW. "Mechanisms Conferring a Rhodococcus species with High Resistance to Benzene." Awarded by:University of New South Wales. School of Microbiology & Immunology, 1999. http://handle.unsw.edu.au/1959.4/19233.
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The Gram-positive bacterium, Rhodococcus sp. 33, was selected for further study to identify the characteristics conferring it with high tolerance to concentrations of benzene. Since most organic solvents, like benzene, are lipophilic, they tend to accumulate within lipid membranes where they express toxicity. The mechanisms conferring this Rhodococcus with resistance to benzene were hypothesised to be located within the subcellular region of this bacterium - cell wall, membrane, and cell-bound polymer. Therefore, this investigation was instigated to identify these mechanisms. To accomplish this, the development of methodologies to isolate highly purified cell wall and membrane fractions, from the organism, were required. To corroborate this investigation, a total of 6 benzene-sensitive mutants were prepared from Rhodococcus sp. 33 and their characteristics compared to those of the parent wild-type strain. 1-D PAGE analysis of proteins revealed various benzene-induced wall, membrane, and cytoplasmic proteins in the w-t. A protein band, with an approximate molecular weight of 58 kDa, was identified to be absent in the most sensitive mutant isolated (mutant M2b). Interestingly, much of this research showed that the benzene-catabolising enzymes played an insignificant role in tolerating the benzene. Gas chromatography and mass spectrometry of whole cell-derived fatty acids revealed that benzene induced an increase in the ratios of saturated/unsaturated fatty acids. Moreover, protein determinations revealed that benzene induced an increase in the concentration of total membrane protein. These increases are suggestive as possible mechanisms to decrease the fluidity of the cell membrane. This was further supported by the observed increase in the generalised polarisation (GP) of laurdan fluorescence in the membranes during growth of the organism with benzene, which is correlated with a decrease in membrane fluidity. The organism was also found to synthesise hexadecenoic acid, 16:1w6c (11 - 13% of total fatty acids), an uncommon fatty acid and previously unreported in other Rhodococcus spp. Analysis of the organism's cell-bound extracellular polymer revealed it to be composed of polysaccharide with biosurfactant-like properties. Its function is proposed to act as a surfactant layer outside the cell, concentrating the benzene within its matrix and reducing benzene's contact with the cell membrane.
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Duffey, John. "Chemical and enzyme catalysed hydroxylation pathways in the synthesis of arene oxides and quinoline alkaloids." Thesis, Queen's University Belfast, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295411.
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Ульєв, Л. М., С. А. Болдирєв, and М. А. Васильєв. "Діагностика процесу дистиляції бензолу." Thesis, Видавництво СумДУ, 2010. http://essuir.sumdu.edu.ua/handle/123456789/13662.
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Bertea, Leopold E. "Catalytic vapour-phase nitration of benzene over zeolites /." [S.l.], 1993. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10258.
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Zaman, Kamruz Md. "BENZENE-1,3-DIAMIDOETHANETHIOL (BDETH2) AND ITS METAL COMPOUNDS." UKnowledge, 2008. http://uknowledge.uky.edu/gradschool_diss/644.
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There is a global need to find a permanent and readily implemented solution to the problem of heavy metal pollution in aqueous environments. A dithiol compound, benzene-1,3-diamidoethanethiol (BDETH2), also known as N,N'-bis(2-mercaptoethyl) isophthalamide or N,N'-bis(2-mercaptoethyl)-1,3-benzenedicarboxamide, capable of binding divalent metal ions, has been synthesized and characterized. A broad range of BDET-metal compounds, spanning the periodic chart, has been prepared and characterized by IR, MS, EA, Raman, XAFS and TGA. The characteristics of the BDET-M compounds were determined through secondary reactions. In an effort to derivatize BDET-M compounds through alkylalumination a new cyclic compound, 1,3- bis(4,5-dihydrothiazolo)benzene, has been synthesized by refluxing BDETH2 in the presence of AlMe3.
Mineral coating studies have been performed and it was found that coating with BDET prevents metal leaching. XPS studies indicated that covalent bonds exist between BDET and metals at the mineral surfaces.
BDETH2 is not water soluble and must be used as an ethanolic solution to precipitate metals from water. In an effort to find similar ligands that are water-soluble another dithiol compound, N,N'-bis(2-mercaptoethyl)oxalamide (MOA), and a monothiol compound, N-mercaptoethyl-furoylamide (MFA), have been synthesized. Each was found to precipitate Cd, Hg and Pb from water, to varying degrees. Some metal compounds of MOA, MFA and dithiothreitol (DTT), a watersoluble dithiol compound have been prepared and characterized. These compounds provide insight into the properties of the BDET-M compounds. For example, it was shown that insolubility in water is a common feature of thiol compounds and is not unique to BDET-M compounds.
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Trmcic, Jelena. "Electrophilic fluorination of ethers and deactivated benzene derivatives." Thesis, Durham University, 2005. http://etheses.dur.ac.uk/2769/.
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Chapter 1 - Chapter 1 provides a literature review of the relevant topics for this thesis in organofluorine chemistry: effect of fluorine as a substituent on the molecule, synthesis of C-F bond from C-H bond using electrophilic reagents with discussions of mechanisms. Chapter 2 ― Direct fluorination of electron-rich systems such as alkyl and cyclic saturated ethers using elemental fluorine results in the formation of unexpected products: fluorinated aldal acetáis. Selectfluor™ was also used to prepare these products in good yield, but also to gain information about mechanism. Chapter 3 - Same methodology for fluorination of deactivated benzene derivatives using elemental fluorine was applied and resulted in a selective substitution of hydrogen by fluorine and allowed the synthesis of a diverse collection of polyfunctional monofluorinated aromatic products. Chapter 4 - Fluorination of 1,3- and 1,4-disubstituted benzaldehyde derivatives was studied in the reactions with elemental fluorine and resulted usually in mixtures of two products. It is concluded that the distribution of the two competing products is dependent on the total electric effect of the substituent (σ-value) attached to the aromatic ring. Chapter 5 - Our research group has developed a microreactor for the purpose of selective fluorination of a wide range of compounds such as benzaldehydes and nitrobenzenes. Low inventories of fluorine gas, in contact with reagents, provide increased safety. Optimization was obtained by varying substrate flow rate, and often resulted in a good conversion and superior yields. Chapter 6-9- Experimental details of the work discussed in Chapters 2-5.
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Tuttle, William Duncan. "Electronic and photoelectron spectroscopy of substituted benzene molecules." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/54244/.
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Intramolecular vibrational redistribution (IVR) has long been investigated in para-fluorotoluene (pFT), with many comparisons made to para-difluorobenzene (pDFB). These comparisons have shown an increased IVR rate for pFT compared to pDFB at similar internal energies, and there are two factors which could influence this - the addition of the methyl group and the lowering of the symmetry of the molecule. This thesis looks to separate these two effects by introducing a comparison of pFT to para-chlorofluorobenzene, as well as an additional comparison of para-xylene (pXyl) to pDFB. Resonance-enhanced multiphoton ionisation (REMPI) spectra of these four molecules are presented, with zero-electron-kinetic-energy (ZEKE) photoelectron spectra recorded via many intermediate levels up to ~00+1200 cm-1 for both pFT and pXyl. These ZEKE spectra allow the assignment of many torsional, vibrational and vibration-torsion levels in these two molecules, with pXyl treated with the appropriate G72 molecular symmetry group for the first time. Several reassignments, as well as many new assignments, are presented for pFT and pXyl. Use of the REMPI and ZEKE techniques allows for the probing of any couplings between levels in the S1 state, as well as providing ground state cation information, and this is supplemented by comparison of REMPI activity between the four para-disubstituted benzene molecules. Proposed couplings, which appear to become more widespread at higher internal energies, are supported by density of states calculations, and a discussion of the influence of both the methyl group and the molecular symmetry on the couplings is presented.
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Khalade, Abdul. "Occupational exposure to benzene and risk of cancer." Thesis, University of Birmingham, 2010. http://etheses.bham.ac.uk//id/eprint/1076/.
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This thesis assessed the risk of cancer in relation to exposure from benzene at work. The thesis is in three major sections. The first section consisted of a systematic review and meta-analysis to assess the risk of leukemia from occupational exposure to benzene. The systematic review confirmed leukemia to be important in relation to benzene exposure; 15 selected studies yielded 16 effect estimates with an overall statistically significant effect size (relative risk) of 1.40 (95% CI, 1.23-1.57). A dose response analysis was performed and provided evidence for a strong positive trend between leukemia risks and estimated exposure to benzene. The risk of all leukemia combined increased with a dose-response pattern with a summary effect size (ES) of 1.64 (95% CI 1.13-2.39) for low (<40 ppm-years), 1.90 (95% CI 1.26-2.89) for medium (40-99.9 ppm-years), and 2.62 (95% CI 1.57-4.39) for high exposure (>100 ppm-years). The risk of AML also increased from low (ES 1.94, 95% CI 0.95-3.95), medium (ES 2.32, 95% CI 0.91-5.94) to high exposure category (ES 3.20, 95% CI 1.09-9.45), but the trend was not statistically significant. The second section used the same method to assess other cancer risks by conducting a systematic review and further meta-analysis. The most common other cancer sites for which a possible occupational involvement from benzene has been suggested were lung, bladder, melanoma, stomach and kidney cancer. Consequently, a systematic review and meta-analysis was performed on each of these cancer sites. The results obtained did not show any clear evidence of risk for lung cancer (ES 0.99, 95% CI 0.96-1.03), bladder cancer (ES 1.00, 95% CI 0.96-1.03), or stomach cancer (ES 0.96, 95% CI 0.90-1.03). However increased risks were shown for melanoma (ES 1.25, 95% CI 1.09-1.44) and kidney cancer (ES 1.14, 95% CI 1.04-1.25). The systematic review and meta-analysis for melanoma was based on 7 available studies reporting 8 cohorts. It was not possible to conclude that benzene exposure is a cause of melanoma as many other chemicals were also used in the factories. There was no significant heterogeneity in the study-specific findings for melanoma (P=0.26). The systematic review and meta-analysis for kidney cancer was based on 22 available studies reporting 24 cohorts. There was also no significant heterogeneity in the study-specific findings for kidney cancer (P=0.41). Therefore, further research is needed to establish a strong link between exposure to benzene and risk of kidney cancer. The final section of the thesis examined the risk of leukemia, lung cancer and all cause mortality in workers exposed to benzene in a large cohort of workers employed at 233 factories during 1966/67 in England & Wales. The results however provided no clear evidence of a dose response effect for leukemia risks in relation to estimated cumulative exposure from benzene. The major limitations of the study related to the recording of limited work histories and the collection of incomplete or limited exposure assessments. The method used in recording the levels of exposure were not clear as different factories were measured by individual personnel at differing times over the years, and at differing areas within factory to factory. It was not possible, therefore, to gain a comprehensive and consistent exposure assessment throughout the factories. To obtain an accurate and viable outcome there needs to be a sound measurement of exposure technique implemented such as taking personal samples using a personal sampler for each individual and indicating specific areas where low, medium and high exposures are evident alongside adequate ventilation. Job exposure matrix also needs to be considered alongside socio-economic classification and ethnicity as this may show some effect on how different minorities may be better or worse adapted to certain chemical exposures.
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Koskinen, T. T., J. I. Moses, R. A. West, S. Guerlet, and A. Jouchoux. "The detection of benzene in Saturn's upper atmosphere." AMER GEOPHYSICAL UNION, 2016. http://hdl.handle.net/10150/621596.
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The stratosphere of Saturn contains a photochemical haze that appears thicker at the poles and may originate from chemistry driven by the aurora. Models suggest that the formation of hydrocarbon haze is initiated at high altitudes by the production of benzene, which is followed by the formation of heavier ring polycyclic aromatic hydrocarbons. Until now there have been no observations of hydrocarbons or photochemical haze in the production region to constrain these models. We report the first vertical profiles of benzene and constraints on haze opacity in the upper atmosphere of Saturn retrieved from Cassini Ultraviolet Imaging Spectrograph stellar occultations. We detect benzene at several different latitudes and find that the observed abundances of benzene can be produced by solar-driven ion chemistry that is enhanced at high latitudes in the northern hemisphere during spring. We also detect evidence for condensation and haze at high southern latitudes in the polar night.
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Tive, Emmanuel. "Synthetic Approaches to 1,2-bis (3,3,3-trifluoropropynyl) Benzene." Bowling Green State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1224544914.
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Dale, Sophie H. "The supramolecular chemistry of benzene- and pyridinepolycarboxylic acids." Thesis, Loughborough University, 2004. https://dspace.lboro.ac.uk/2134/34271.
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The term ‘supramolecular chemistry' was defined by Lehn as ‘chemistry beyond the molecule', the aggregation of molecular or ionic entities to yield extensive arrays. Supramolecular chemistry is essentially the designed chemistry of the intermolecular bond, encircling the traditionally distinct disciplines of organic, inorganic and physical chemistry. Metal-organic frameworks have been shown to facilitate selective gas sorption and selective binding of guest solvent molecules, with notable examples from the work of Yaghi et al. created from the coordination of benzenepolycarboxylates to metal centres. Authors including Herbstein have investigated the inclusion of solvent molecules in the solid-state structure of trimesic acid, preventing the interpenetration of this compound. Here, novel solvent inclusion compounds of hemimellitic acid, the 1,2,3-trisubstituted relative of trimesic acid, are presented in which the hydrogen bonded host network forms cavities in which solvent molecules reside.
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Silva, Giselli Luzia Ferreira da. "O papel do cloro na hidrogenação parcial do benzeno com catalisadores de rutenio." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266743.
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Orientador: Antonio Jose Gomez Cobo, Adler Gomes MouraDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: A hidrogenação parcial do benzeno é uma reação química de grande interesse científico e industrial, uma vez que o cicloexeno formado pode ser empregado na obtenção de diversos produtos, em razão da sua dupla ligação altamente reativa. O presente trabalho tem como objetivo principal estudar os efeitos do cloro em catalisadores de Ru/CeO2, destinados à hidrogenação parcial do benzeno. Com o intuito de verificar a influência da natureza do suporte, catalisadores de Ru/Al2O3 também foram estudados, como referência, uma vez que a alumina é um suporte não redutível. Para tal, catalisadores com uma fração mássica de metal de cerca de 5 % foram preparados através do método de impregnação a seco. Após a adição do precursor clorado RuCl3xH2O ao suporte, os catalisadores foram submetidos a tratamentos térmicos consecutivos de redução direta a 573K. Os sólidos obtidos foram caracterizados através das técnicas de adsorção de N2 (método B.E.T.), microscopia eletrônica de varredura com microssonda para análise espectrométrica de raios X (MEV + EDX), espectrometria de fotoelétrons excitados por raios X (XPS) e redução à temperatura programada (TPR). O desempenho dos catalisadores foi avaliado nas reações de hidrogenação do benzeno e de hidrogenação do cicloexeno, empregando-se um reator Parr do tipo "slurry". A reação foi conduzida à pressão de hidrogênio constante de 5 Mpa e à temperatura de 373 K, em meio reacional trifásico contendo água. Em alguns testes catalíticos realizados, soluções aquosas de TiCl3, NaCl, ZnCl2 ou HCl foram adicionadas ao meio reacional. Os resultados da caracterização revelam que o cloro, oriundo do precursor clorado, praticamente não é eliminado do catalisador Ru/CeO2, mesmo após os sucessivos tratamentos de redução. Na reação de hidrogenação do benzeno, o catalisador Ru/CeO2, reduzido duas vezes consecutivas, apresenta os maiores rendimentos de cicloexeno, tanto na ausência, quanto na presença de TiCl3 no meio reacional. Dentre os aditivos empregados no meio reacional, o TiCl3 conduz aos maiores rendimentos de cicloexeno
Abstract: The partial hydrogenation of the benzene is a chemical reaction of great scientific and industrial interest, since the produzed cyclohexeno can be used in the attainment of diverse products, in reason of its highly reactive double bond. The present work has as main objective to study the effect of chlorine in Ru/CeO2 catalysts, destined to the partial hydrogenation of the benzene. With intention to verify the influence of the nature of the support, Ru/Al2O3 catalysts have been also studied, as reference, since that alumina is a not reducible support. For such, catalysts with a mass metal fraction of about 5 % were prepared by the wet impregnation technique. After the addition of the chloride precursor RuCl3xH2O to the support, the catalysts were submitted to consecutive thermal treatments of direct reduction at 573K. The gotten solids have been characterized by N2 adsorption (method B.E.T.), electronic scanning microscopy with energy dispersive X-ray spectroscopy analysis (MEV+EDX), X-ray photolectron spectroscopy (XPS) and temperature-programmed reduction (TPR) techniques. The performance of the catalysts have been evaluated in the reactions of benzene hydrogenation and cyclohexeno hydrogenation, using a Parr reactor of the type "slurry". The reaction has been carried out at 5 Mpa constant hydrogen pressure and 373K temperature, in a three-phase reacional system with water. In some catalysts tests, aqueous solutions of TiCl3, NaCl, ZnCl2 or HCl have been added to the reacional system. The results of the characterization show that the chlorine, from the chloride precursor, is practically not eliminated of the Ru/CeO2 catalyst, after the successive treatments of reduction. In the benzene hydrogenation reaction, the Ru/CeO2 catalyst, reduced two consecutive times, presents the biggest yields of cyclohexeno, as in the absence, as in the presence of TiCl3 in the reacional system. Among additives used in the reacional system, the TiCl3 leads to the biggest yields of cicloexeno
Mestrado
Sistemas de Processos Quimicos e Informatica
Mestre em Engenharia Química
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VIEIRA, Kátia Cristina de Melo Tavares. "Efeitos da exposição à mistura comercial de gasolina/etanol sobre a função reprodutiva masculina em modelo experimental." Universidade do Oeste Paulista, 2018. http://bdtd.unoeste.br:8080/jspui/handle/jspui/1083.
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Leaks at gas stations cause major problems for the environment, especially with regard to contamination of groundwater and soils. The major problems of oil derivative contamination are attributed to monoaromatic hydrocarbons (BTEX - benzene, toluene and xylene), which are the most soluble and mobile constituents of the gasoline fraction, being the first to reach the water table. In the most recent survey carried out by the State Company of Environmental Sanitation Technology of the State of São Paulo (CETESB), it was identified that more than 85% of the contamination cases in the region of West Paulista are related to waste from fuel stations. The present study evaluated the toxicological potential of exposure of adult male rats to the commercial gasoline / ethanol blend (75/25 by volume), with emphasis on the possible impacts on reproductive morphophysiology. Adult male Wistar rats were allocated into 4 experimental groups (n = 8 / group). The animals received commercial gasoline diluted in corn oil via gavage at doses of 0 (control group- C), 16 (group A - GA), 160 (group B - GB) or 800 mg / kg / day (group C - GC). The reproductive organs were collected and weighed. The sperm parameters evaluated were motility, plasma membrane integrity and acrosomal, mitochondrial activity and morphology. In addition, the epididymis and right testis were collected for sperm counts. Histopathological analysis of the testis and epididymis, spermatogenesis and cell counts. For the machine learning test, different pattern recognition algorithms were used: Artificial Neural Network (ANN), Bayes Classifier (BAY), K-Nearest Neighbors (KNN), Support Vector Machine (SVM) and Optimum Path Forest OPF). The results were compared by ANOVA with Tukey's posterior test, and the Kruskall-Wallis test with Dunn's a posteriori, considering p <0.05. The sperm parameters were reduced in a dose-dependent manner. Mitochondrial activity and acrosomal integrity were decreased in the GC and GB groups in relation to the control group. There was an increase of isolated heads in the GC and GB groups in relation to the control group. Plasma membrane integrity was reduced in GC in relation to the control group. A decrease in the number of mobile spermatozoa with progressive trajectory was observed in the GC and GB groups, in relation to the control group. The daily sperm production was reduced in GC and GB in relation to the control group. In addition, this parameter was lower in GC than in GB. There was a significant delay in transit time in the tail of the epididymis in the GC and GB groups in relation to the control group. The number of Sertoli cells decreased in the GB and GC groups when compared to the CG and GB groups. Histopathological analysis, spermatogenesis and germ cell counts showed no significant difference between the groups. There was presence of pattern with the subdivision of two classes (control group and exposed groups), with better classification with the SVM test and 90% accuracy for control group. Thus, it was concluded that the exposure of rats to different doses of the commercial gasoline / ethanol mixture can alter spermatogenesis and sperm quality, with a recognizable classification pattern of machine learning algorithms.
Vazamentos em postos de combustíveis provocam grandes problemas ao meio ambiente, principalmente no que diz respeito à contaminação de águas subterrâneas e solos. Os maiores problemas da contaminação por derivados de petróleo são atribuídos aos hidrocarbonetos monoaromáticos (BTEX - benzeno, tolueno e xileno), que são os constituintes mais solúveis e mais móveis da fração da gasolina, sendo os primeiros a atingir o lençol freático. No mais recente levantamento realizado pela Companhia Estadual de Tecnologia de Saneamento Ambiental do Estado de São Paulo (CETESB), identificou-se que mais de 85% dos casos de contaminação na região do Oeste Paulista estão relacionados a resíduos de postos de combustíveis. O presente estudo avaliou o potencial toxicológico da exposição de ratos machos adultos à mistura comercial de gasolina/etanol (75/25 em volume), com ênfase nos possíveis impactos sobre a morfofisiologia reprodutiva. Ratos machos Wistar adultos foram alocados em 4 grupos experimentais (n=8/grupo). Os animais receberam gasolina comercial diluída em óleo de milho, via gavagem, nas doses de 0 (grupo controle - C), 16 (grupo A - GA), 160 (grupo B - GB) ou 800 mg/kg/dia (grupo C - GC). Os órgãos reprodutivos foram coletados e pesados. Os parâmetros espermáticos avaliados foram motilidade, integridade da membrana plasmática e acrossomal, atividade mitocondrial e morfologia. Além disso, o epidídimo e testículo direito foram coletados para contagens espermáticas. Também foram realizadas análise histopatológica do testículo e epidídimo, contagens dos estágios da espermatogênese e de células. Para o teste de aprendizado de máquina foram utilizados diferentes algoritmos de reconhecimento de padrões: Artificial Neural Network (ANN), Bayes Classifier (BAY), K-Nearest Neighbors (K-NN), Support Vector Machine (SVM) e Optimum Path Forest (OPF). Os resultados foram comparados por ANOVA com o teste “a posteriori” de Tukey, e o teste de Kruskall-Wallis, com “a posteriori” de Dunn, considerando p<0,05. Os parâmetros espermáticos foram reduzidos de maneira dose-dependente. A atividade mitocondrial e integridade acrossomal foram diminuídas nos grupos GC e GB em relação ao grupo controle. Houve um aumento de cabeças isoladas nos grupos GC e GB em relação ao grupo controle. A integridade de membrana plasmática foi reduzida em GC em relação ao grupo controle. Foi observada uma redução no número de espermatozoides móveis com trajetória progressiva nos grupos GC e GB, em relação ao grupo controle. A produção diária espermática foi reduzida em GC e GB em relação ao grupo controle. Além disso, este parâmetro foi menor em GC em relação a GB. Houve um atraso significativo no tempo de trânsito na cauda do epidídimo nos grupos GC e GB em relação ao grupo controle. O número de células de Sertoli sofreu redução nos grupos GC e GB quando comparado aos grupos controle e GA. A análise histopatológica, contagem dos estágios da espermatogênese e de celulas germinativas não apresentaram diferença significativa entre os grupos. Houve presença de padrão com a subdivisão de duas classes (grupo controle e grupos expostos), com melhor classificação com o teste SVM e 90% de acurácia para o grupo controle. Assim, concluiu-se que a exposição de ratos a diferentes doses da mistura comercial de gasolina/etanol pode alterar a espermatogênese e a qualidade espermática, com reconhecível padrão de classificação de algoritmos de aprendizado de máquina.
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com, Anthonyhorton@bigpond, and Anthony Horton. "Non-industrial personal benzene exposure in a mediterranean climate." Murdoch University, 2006. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20070830.143310.
Full textAbstract:
Benzene is a volatile organic air pollutant that is ubiquitous in the environment. It is frequently reported in urban airsheds, principally as a result of evaporative emissions from motor vehicles. Increasingly stringent fuel quality standards have resulted in lower mean benzene concentrations in many urban airsheds, however the concentrations reported indoors can be higher than those in urban airsheds. Mean indoor benzene concentrations can reach one order of magnitude higher than those reported in urban airsheds. Long term exposure to very high benzene concentrations can result in leukemia, however the health risks of long term non-industrial exposure in the general public are currently uncertain.
An important part of determining the risks of non-industrial benzene exposure is to first determine the influence of various activities on 24-hour personal benzene exposure. Previous research has identified commuting in a private motor vehicle and refuelling with low benzene fuel as statistically significant contributors to nonindustrial benzene exposure in the Northern Hemisphere, however none has quantified the increase in benzene exposure as a result of these activities over a 24-hour period in the Mediterranean climate. The results of the 1987 TEAM study in the South Bay section of California reported that automobile exhaust was a significant contributor to non-industrial benzene exposure based on exhaled breath concentrations (p<0.05) and commuting in a private vehicle (p=0.0003) and refuelling (0.05) were important contributors based on personal benzene exposure concentrations (Wallace et al., 1988).
The aims of this thesis were to identify the roles and importance of selected activities in personal exposure to benzene, to determine the increase in 24-hour personal benzene exposure attributable to these activities and quantify the risk posed by these activities in a Mediterranean climate. In particular, the aim of this thesis was to investigate whether commuting in a private motor vehicle and refuelling are significant contributors to non-industrial personal benzene exposure in a Mediterranean climate, or whether lifestyle and climate interact.
This research was composed of a personal exposure study, a source monitoring study and a risk assessment. A cross-sectional personal exposure study was conducted for two reasons. Firstly, to quantify the mean personal benzene concentrations to which a representative sample of the general public of Perth was exposed as a result of their daily activities and behaviours. Secondly, to quantify the frequency of commuting by private motor vehicle and refuelling with low benzene fuel in Perth. Fifty participants were recruited for the personal exposure study, and asked to wear a monitor for 24-hour period(including weekends) in summer and winter and record their activities and locations in a diary. Prior to the monitoring they were asked to complete a questionnaire seeking background information on their home, lifestyle and behaviours. The results of the research revealed that there was not a statistically significant difference between the personal benzene exposure concentrations in summer and winter. An analysis of the questionnaire and time activity diary data using a generalised linear mixed model revealed that the time spent commuting in a private motor vehicle (â= 0.281, p<0.0001) and refuelling with low benzene fuel (â = 0.194, p=0.033) were statistically significant contributors to non-industrial benzene exposure. Each hour spent commuting resulted in a mean increase in 24-hour personal exposure of 0.74 ìgm-3 (â= 0.729 ìg m-3, p< 0.0001). The mean increase in exposure per hour of commuting in a private motor vehicle was larger in winter (â= 0.8 ìg m-3, p=0.008) than summer (â= 0.67 ìg m-3, p=0.004). Refuelling increased personal exposure by 1.50 ìg m-3 (1.49, p<0.0001) in each 24-period when refuelling was reported.
Benzene source monitoring was conducted at selected locations in Perth for two reasons. Firstly, data quantifying non-industrial personal benzene exposure during refuelling and commuting in a private vehicle in Perth was needed, and secondly, to make an assessment of risk attributable to these activities.
Benzene source measurements were conducted in two carparks in the Central Business District (CBD), in the vicinity of the northbound and southbound lanes of the Kwinana Freeway, and at a petrol station. The 7- day arithmetic mean benzene concentrations in the carparks were 4.49 ìg m-3 and 1.23 ìg m-3. The 7-day mean benzene concentrations northbound on the Kwinana Freeway was 2.78 ìg m-3, and the mean benzene concentration southbound was 2.57 ìg m-3. Benzene emissions in the carpark and on the Kwinana Freeway were measured during vehicle idling, which is representative of vehicle speed during heavy vehicle traffic. Benzene emissions at the petrol station were monitored in the vicinity of the petrol bowser, which is representative of emissions during refuelling. The 24-hour mean benzene concentration at the petrol station bowser was 38.15 ìg m-3.
The results of this research revealed that refuelling and commuting in a private vehicle are the most significant contributors to non-industrial benzene exposure in Perth, and that the contribution of these two activities in Perth is far greater than in previous published research, on the basis of the results obtained from the generalised linear model. The results of this research quantified the increase in non-industrial benzene exposure from refuelling and commuting in a private motor vehicle in a Mediterranean climate for the first time, and quantified the lifetime excess cancer risk attributable to these activities in a Mediterranean climate for the first time. The lifetime excess cancer unit risks of these two activities in a Mediterranean climate were 7.4x10-5 or 7.4 per 100000 population for commuting and 15.03 x 10-4 or 15 per 10000 for refuelling.
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Tatarko, John L. "The Thermodynamics of Fluid-Phase Benzene via Molecular Simulation." Cleveland State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=csu1292004756.
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Vladisavljevic, Milos. "Electronic and Optical Properties of an Artificial Benzene Ring." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31724.
Full textAbstract:
In this thesis, we develop the methodology for exploring the electronic and optical
properties of an artificial benzene ring, both analytically as well as numerically
through direct diagonalization using the configuration interaction method. We
use the extended Hubbard Hamiltonian to model the interactions with different
numbers of electrons, with spin projection and total spin resolved as good quantum
numbers. The focus in this work is on the charged case and the emergence of an
artificial gauge field and how it can be detected optically. We also examine three
other cases of the artificial benzene ring, the single electron case, the charge neutral
or half filled case, and the quarter filled case. Ground state properties, excited
state spectra, and interactions with light are described.
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Sejnoha, Milena. "Vapour-liquid equilibria of benzene and cyclohexane with CO2." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66092.
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Cade, Ian Alexander. "Antenna modified ethynyl benzene ligands and their metal complexes." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417275.
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Al-Hazmi, Naeem. "One step hydroxylation of benzene to phenol using N2O." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/8299.
Full textAbstract:
There is an increasing commercial interest in finding alternative ways to produce phenol that overcome the disadvantages of the current cumene process used to synthesize phenol. The drivers for the change are both economic and environmental. A direct oxidation route for producing phenol from benzene is based on using N2O as an oxidizing agent in the gas phase in the presence of modified Fe-ZSM5 zeolite. One of the main objectives was to examine the effect of different Si/Al ratios, temperatures and iron content on the selective conversion of benzene to phenol with a desire to achieve high selectivity and minimise catalyst deactivation. Also one of the research objectives was to identify the active sites in the catalyst and design the catalyst which is able to delay coke formation. The methodology was to incorporate iron directly at extra-framework positions via liquid ion-exchange. In this project, a series of selective Fe-ZSM5 catalysts with different Si/Al ratios have been prepared and evaluated for selective formation of phenol. The catalyst samples were characterized (by Atomic Absorption Spectroscopy (AAS), Malvern mastersizer and Nitrogen adsorption using N2 at 77 K via Micromeritics to determine the elemental composition, average particle size, BET surface area and pore size distribution) and their catalytic activities compared. A quantitative comparison between the number of active sites using isopropylamine decomposition method shows that active sites increase as the Si/Al ratio increased and also as the iron content increased. (Continues...).
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Bagneris, Claire. "Protein engineering of benzene dioxygenase for altered substrate specificity." Thesis, King's College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326106.
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Benish, Timothy George 1971. "PAH radical scavenging in fuel-rich premized benzene flames." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85279.
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Harvey, Rebecca. "Dearomatising addition of tethered organolithiums to activated benzene derivatives." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/dearomatising-addition-of-tethered-organolithiums-to-activated-benzene-derivatives(03f09832-90da-4995-8b8e-a1f5fe7cf2ff).html.
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This thesis describes research carried out on the synthesis of lithiation precursors used to investigate the ability of oxazoline activated benzene derivatives to undergo dearomatising cyclisations. Chapter 1 illustrates previous work in the area of dearomatising additions, including intra- and inter-molecular dearomatisations. An overview of relevant work conducted within the Clayden group is also described. Chapter 2 narrates the synthesis of lithiation precursors that contain a (4R,5R)-4,5-diphenyloxazoline activating group on the aromatic ring. The attempts to lithiate and dearomatise these compounds are shown. Chapter 3 describes the synthesis of achiral oxazoline activated O-allylic pre-lithiation substrates, and their ability to undergo dearomatising cyclisations. Also described is the attempts to find a suitable protecting group for N-allylic dearomatising cyclisations. Chapter 4 outlines the investigations carried out for the stereoselective synthesis of (4R,5R)-4,5-diphenyloxazolines, which have been used for the activation towards dearomatising cyclisation. Chapter 5 is an overview of the thesis and outlines possible future work.Chapter 6 contains the experimental methods and data pertaining to Chapters 2 to 5.
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Rivas, Isabelle Marie. "Cometabolic transformation of thiophene with benzene as primary substrate /." Environment & Ressources DTU, Technical University of Denmark, 2001. http://www2.er.dtu.dk/publications/fulltext/2001/MR2001-103.pdf.
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Horton, Anthony. "Non-industrial personal benzene exposure in a mediterranean climate." Thesis, Horton, Anthony (2006) Non-industrial personal benzene exposure in a mediterranean climate. PhD thesis, Murdoch University, 2006. https://researchrepository.murdoch.edu.au/id/eprint/77/.
Full textAbstract:
Benzene is a volatile organic air pollutant that is ubiquitous in the environment. It is frequently reported in urban airsheds, principally as a result of evaporative emissions from motor vehicles. Increasingly stringent fuel quality standards have resulted in lower mean benzene concentrations in many urban airsheds, however the concentrations reported indoors can be higher than those in urban airsheds. Mean indoor benzene concentrations can reach one order of magnitude higher than those reported in urban airsheds. Long term exposure to very high benzene concentrations can result in leukemia, however the health risks of long term non-industrial exposure in the general public are currently uncertain.
An important part of determining the risks of non-industrial benzene exposure is to first determine the influence of various activities on 24-hour personal benzene exposure. Previous research has identified commuting in a private motor vehicle and refuelling with low benzene fuel as statistically significant contributors to nonindustrial benzene exposure in the Northern Hemisphere, however none has quantified the increase in benzene exposure as a result of these activities over a 24-hour period in the Mediterranean climate. The results of the 1987 TEAM study in the South Bay section of California reported that automobile exhaust was a significant contributor to non-industrial benzene exposure based on exhaled breath concentrations (p<0.05) and commuting in a private vehicle (p=0.0003) and refuelling (0.05) were important contributors based on personal benzene exposure concentrations (Wallace et al., 1988).
The aims of this thesis were to identify the roles and importance of selected activities in personal exposure to benzene, to determine the increase in 24-hour personal benzene exposure attributable to these activities and quantify the risk posed by these activities in a Mediterranean climate. In particular, the aim of this thesis was to investigate whether commuting in a private motor vehicle and refuelling are significant contributors to non-industrial personal benzene exposure in a Mediterranean climate, or whether lifestyle and climate interact.
This research was composed of a personal exposure study, a source monitoring study and a risk assessment. A cross-sectional personal exposure study was conducted for two reasons. Firstly, to quantify the mean personal benzene concentrations to which a representative sample of the general public of Perth was exposed as a result of their daily activities and behaviours. Secondly, to quantify the frequency of commuting by private motor vehicle and refuelling with low benzene fuel in Perth. Fifty participants were recruited for the personal exposure study, and asked to wear a monitor for 24-hour period (including weekends) in summer and winter and record their activities and locations in a diary. Prior to the monitoring they were asked to complete a questionnaire seeking background information on their home, lifestyle and behaviours. The results of the research revealed that there was not a statistically significant difference between the personal benzene exposure concentrations in summer and winter. An analysis of the questionnaire and time activity diary data using a generalised linear mixed model revealed that the time spent commuting in a private motor vehicle (beta= 0.281, p<0.0001) and refuelling with low benzene fuel (beta = 0.194, p=0.033) were statistically significant contributors to non-industrial benzene exposure. Each hour spent commuting resulted in a mean increase in 24-hour personal exposure of 0.74 mcg-3 (beta= 0.729 mcg m-3, p<0.0001). The mean increase in exposure per hour of commuting in a private motor vehicle was larger in winter (beta= 0.8 mcg m-3, p=0.008) than summer (beta= 0.67 mcg m-3, p=0.004). Refuelling increased personal exposure by 1.50 mcg m-3 (1.49, p<0.0001) in each 24-period when refuelling was reported.
Benzene source monitoring was conducted at selected locations in Perth for two reasons. Firstly, data quantifying non-industrial personal benzene exposure during refuelling and commuting in a private vehicle in Perth was needed, and secondly, to make an assessment of risk attributable to these activities.
Benzene source measurements were conducted in two carparks in the Central Business District (CBD), in the vicinity of the northbound and southbound lanes of the Kwinana Freeway, and at a petrol station. The 7- day arithmetic mean benzene concentrations in the carparks were 4.49 mcg m-3 and 1.23 mcg m-3. The 7-day mean benzene concentrations northbound on the Kwinana Freeway was 2.78 mcg m-3, and the mean benzene concentration southbound was 2.57 mcg m-3. Benzene emissions in the carpark and on the Kwinana Freeway were measured during vehicle idling, which is representative of vehicle speed during heavy vehicle traffic. Benzene emissions at the petrol station were monitored in the vicinity of the petrol bowser, which is representative of emissions during refuelling. The 24-hour mean benzene concentration at the petrol station bowser was 38.15 mcg m-3.
The results of this research revealed that refuelling and commuting in a private vehicle are the most significant contributors to non-industrial benzene exposure in Perth, and that the contribution of these two activities in Perth is far greater than in previous published research, on the basis of the results obtained from the generalised linear model. The results of this research quantified the increase in non-industrial benzene exposure from refuelling and commuting in a private motor vehicle in a Mediterranean climate for the first time, and quantified the lifetime excess cancer risk attributable to these activities in a Mediterranean climate for the first time. The lifetime excess cancer unit risks of these two activities in a Mediterranean climate were 7.4 x 10-5 or 7.4 per 100000 population for commuting and 15.03 x 10-4 or 15 per 10000 for refuelling.
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Horton, Anthony. "Non-industrial personal benzene exposure in a mediterranean climate." Horton, Anthony (2006) Non-industrial personal benzene exposure in a mediterranean climate. PhD thesis, Murdoch University, 2006. http://researchrepository.murdoch.edu.au/77/.
Full textAbstract:
Benzene is a volatile organic air pollutant that is ubiquitous in the environment. It is frequently reported in urban airsheds, principally as a result of evaporative emissions from motor vehicles. Increasingly stringent fuel quality standards have resulted in lower mean benzene concentrations in many urban airsheds, however the concentrations reported indoors can be higher than those in urban airsheds. Mean indoor benzene concentrations can reach one order of magnitude higher than those reported in urban airsheds. Long term exposure to very high benzene concentrations can result in leukemia, however the health risks of long term non-industrial exposure in the general public are currently uncertain.
An important part of determining the risks of non-industrial benzene exposure is to first determine the influence of various activities on 24-hour personal benzene exposure. Previous research has identified commuting in a private motor vehicle and refuelling with low benzene fuel as statistically significant contributors to nonindustrial benzene exposure in the Northern Hemisphere, however none has quantified the increase in benzene exposure as a result of these activities over a 24-hour period in the Mediterranean climate. The results of the 1987 TEAM study in the South Bay section of California reported that automobile exhaust was a significant contributor to non-industrial benzene exposure based on exhaled breath concentrations (p<0.05) and commuting in a private vehicle (p=0.0003) and refuelling (0.05) were important contributors based on personal benzene exposure concentrations (Wallace et al., 1988).
The aims of this thesis were to identify the roles and importance of selected activities in personal exposure to benzene, to determine the increase in 24-hour personal benzene exposure attributable to these activities and quantify the risk posed by these activities in a Mediterranean climate. In particular, the aim of this thesis was to investigate whether commuting in a private motor vehicle and refuelling are significant contributors to non-industrial personal benzene exposure in a Mediterranean climate, or whether lifestyle and climate interact.
This research was composed of a personal exposure study, a source monitoring study and a risk assessment. A cross-sectional personal exposure study was conducted for two reasons. Firstly, to quantify the mean personal benzene concentrations to which a representative sample of the general public of Perth was exposed as a result of their daily activities and behaviours. Secondly, to quantify the frequency of commuting by private motor vehicle and refuelling with low benzene fuel in Perth. Fifty participants were recruited for the personal exposure study, and asked to wear a monitor for 24-hour period (including weekends) in summer and winter and record their activities and locations in a diary. Prior to the monitoring they were asked to complete a questionnaire seeking background information on their home, lifestyle and behaviours. The results of the research revealed that there was not a statistically significant difference between the personal benzene exposure concentrations in summer and winter. An analysis of the questionnaire and time activity diary data using a generalised linear mixed model revealed that the time spent commuting in a private motor vehicle (beta= 0.281, p<0.0001) and refuelling with low benzene fuel (beta = 0.194, p=0.033) were statistically significant contributors to non-industrial benzene exposure. Each hour spent commuting resulted in a mean increase in 24-hour personal exposure of 0.74 mcg-3 (beta= 0.729 mcg m-3, p<0.0001). The mean increase in exposure per hour of commuting in a private motor vehicle was larger in winter (beta= 0.8 mcg m-3, p=0.008) than summer (beta= 0.67 mcg m-3, p=0.004). Refuelling increased personal exposure by 1.50 mcg m-3 (1.49, p<0.0001) in each 24-period when refuelling was reported.
Benzene source monitoring was conducted at selected locations in Perth for two reasons. Firstly, data quantifying non-industrial personal benzene exposure during refuelling and commuting in a private vehicle in Perth was needed, and secondly, to make an assessment of risk attributable to these activities.
Benzene source measurements were conducted in two carparks in the Central Business District (CBD), in the vicinity of the northbound and southbound lanes of the Kwinana Freeway, and at a petrol station. The 7- day arithmetic mean benzene concentrations in the carparks were 4.49 mcg m-3 and 1.23 mcg m-3. The 7-day mean benzene concentrations northbound on the Kwinana Freeway was 2.78 mcg m-3, and the mean benzene concentration southbound was 2.57 mcg m-3. Benzene emissions in the carpark and on the Kwinana Freeway were measured during vehicle idling, which is representative of vehicle speed during heavy vehicle traffic. Benzene emissions at the petrol station were monitored in the vicinity of the petrol bowser, which is representative of emissions during refuelling. The 24-hour mean benzene concentration at the petrol station bowser was 38.15 mcg m-3.
The results of this research revealed that refuelling and commuting in a private vehicle are the most significant contributors to non-industrial benzene exposure in Perth, and that the contribution of these two activities in Perth is far greater than in previous published research, on the basis of the results obtained from the generalised linear model. The results of this research quantified the increase in non-industrial benzene exposure from refuelling and commuting in a private motor vehicle in a Mediterranean climate for the first time, and quantified the lifetime excess cancer risk attributable to these activities in a Mediterranean climate for the first time. The lifetime excess cancer unit risks of these two activities in a Mediterranean climate were 7.4 x 10-5 or 7.4 per 100000 population for commuting and 15.03 x 10-4 or 15 per 10000 for refuelling.
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Rabayda, Daniel P. "The Structure and Stability of Cationic Metal-Benzene Clusters." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5823.
Full textAbstract:
We have investigated the size-dependent stability and structure of benzene, aluminum-benzene, and vanadium-benzene clusters. Motivated by gas-phase experimental studies performed by an experimental collaborator, we have used first-principle electronic structure methods to identify the structure of Al+(Bz)n, V+(Bz)n, and Bzn clusters. Our studies reveal that cationic aluminum-benzene clusters have a magic number of 13, and that its high stability may be understood by analyzing the structure of the cluster. We also investigate the structure of vanadium-benzene clusters which have a magic number of 2. Here I examine the benzene-cation and benzene-benzene interactions that lead to these magic numbers, as well as their geometric shell structures and their formation/solvation.
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Ding, Fei. "Stereoselective dearomatization of benzene, alkylated benzenes and naphthalenes by dihapto-coordination /." 2004. http://wwwlib.umi.com/dissertations/fullcit/3118387.
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