Segui questo link per vedere altri tipi di pubblicazioni sul tema: Cyclohexane.
Tesi sul tema "Cyclohexane"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-50 saggi (tesi di laurea o di dottorato) per l'attività di ricerca sul tema "Cyclohexane".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi le tesi di molte aree scientifiche e compila una bibliografia corretta.
1
Sutton, Peter William. "Ketene cycloadditions to cyclohexa-3,5-diene-cis-1,2-diol acetals : preparation of polyhydroxylated cyclohexane derivatives". Thesis, University of Exeter, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294477.
Testo completo
2
Lima, Liliane Schier de. "Oxidação aerobica de cicloexano e cicloexeno usando carvão ativado como catalisador". [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249522.
Testo completoAbstract (sommario):
Orientador: Ulf Friedrich SchuchardtDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica
Made available in DSpace on 2018-08-06T15:18:09Z (GMT). No. of bitstreams: 1 Lima_LilianeSchierde_M.pdf: 699085 bytes, checksum: 864f8f983b1935cceb9fe8d839e3fcf4 (MD5) Previous issue date: 2006
Resumo: O interesse nas reações de oxidação do cicloexano e cicloexeno tem sido foco de muitas pesquisas nos últimos anos, objetivando a busca de reações com maiores rendimentos e seletividades. A rota sintética comercialmente utilizada oxida o cicloexano a cicloexanol e cicloexanona com rendimentos muito baixos (em torno de 4 %), fomentando ainda mais a busca por rotas alternativas de oxidação. O presente trabalho estudou a oxidação direta de cicloexano e cicloexeno a 140ºC e pressões de até 50 bar usando carvões ativados de origem mineral e vegetal como catalisadores. O carvão ativado, por se tratar de um material com uma alta área superficial e de característica hidrofóbica, é compatível com reações de hidrocarbonetos e, então, foi utilizado como catalisador para estas oxidações. As oxidações diretas do cicloexano, nas condições em que foram realizadas, apresentaram resultados de conversão abaixo de 1% e, em alguns casos, com resultados irreprodutíveis. Para as reações de oxidação do cicloexeno, além de algumas mudanças nas condições das reações, foram utilizados como catalisadores carvão ativado impregnados com Pd. As reações apresentaram boas conversões, que variaram de 5 a 90%. Os carvões minerais previamente tratados com ácido clorídrico conduziram a melhores resultados nas oxidações catalíticas do cicloexeno, porém um comportamento inverso foi observado para os carvões vegetais. O Pd impregnado favoreceu a formação da bifenila, alcançando 100% de seletividade para este produto quando usou-se um carvão comercial contendo 5% de Pd.
Abstract: The concerning about cyclohexane and cyclohexene oxidation reactions has been subject of many researches lately, in order to find yielder and more selective reactions. The more common synthetic path at the industry, oxidate the cyclohexane to cyclohexanol and cyclohexanone with very low yield (almost 4%), what stimulates the researches looking for alternatives oxidations paths. The present work has studied the straight oxidation from the cyclohexane and cyclohexene in a temperature of 140°C and pressures until 50 bars using activated carbon, mineral and vegetal origins, as a catalyser. Due the activated carbon is a material with very high surface area and it has also hydrophobic characteristics, it is compatible with hydrocarbons reactions, and then it has been used here as catalyser to this oxidations. The straight cyclohexane oxidations, in that conditions, has showed conversion results lower than 1% and, in some cases, with non reproducible results. To the cyclohexene oxidation reactions, besides some changes in the reactions conditions, it has been used as a catalyser, activated carbon impregnated with Pd. Those reactions showed better conversions, between 5% and 90%. The mineral carbons, previously treated with chloride acid, lead to better results in the catalytic oxidation of the cyclohexene, although an inverse behavior has been observed to the vegetal carbons. The Pd impregnation has helped the biphenyl production, reaching 100% selectivity to this product when using a carbon containing 5% of Pd.
Mestrado
Quimica Organica
Mestre em Química
3
Mitropetros, Konstantinos. "Shock induced bubble explosions in liquid cyclohexane". [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=974965936.
Testo completo
4
Graham, Isla Patricia. "Chemoenzymatic approches to cyclohexane based natural products". Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485199.
Testo completoAbstract (sommario):
Chapter 1 provides an overview of cis-dihydrodiols. The biological aspects of enzymatic hydroxylation are discussed, followed by the important stereochemical aspects of cis-diol metabolites. A selection of chemoenzymatic approaches to important natural products from cis-dihydrodiols is given. Chapter 2 introduces the Amaryllidaceae and Sceletium alkaloids, giving an insight into their biological sigIJificance. Previous approaches to important members of both alkaloid classes are given. Synthesis of a ke~ intermediate for the synthesis of mesembranol is described. The development of successful conditions to effect a Suzuki reaction of cis-dihydrodiols forms a key component of the synthetic strategy. Following on from this, Diels-Alder reactions of substrates derived from cisdihydrodiols, studies towards a resolving agent and biotransformation studies are discussed. Chapter 3 is devoted to synthesis of cis-3a-aryloctahydroindole nuclei, common to many Amaryllidaceae alkaloids. Previous approaches followed by our synthetic endeavours to gain access to this nucleus from cis-dihydrodiols are outlined. Chapter 4 begins with an introduction to 2-deoxystreptamine, an important aminocyclitol. Previous approaches to 2-deoxystreptamine are discussed. An important intermediate in several synthe~es is identified, followed by approaches to it from cis-dihydrodiols. The second half of the chapter is concerned with synthesis of valeinamine. Synthesis of a 3,4-trans-diol from iodobenzene-cis-diol is outlined. Chapter 5 contains full experimental details, including spectral and analytical data, for the compounds synthesised during this work.
5
Durie, Alastair J. "Multivicinal fluorine substitution of the cyclohexane ring". Thesis, University of St Andrews, 2014. http://hdl.handle.net/10023/8080.
Testo completoAbstract (sommario):
Highly polar organic fluorinated motifs are of interest in materials chemistry, for example, in liquid crystal applications. Cyclohexane is an important and widely used structural motif within organic chemistry. Work has been carried out to prepare single stereoisomers of multivicinal fluorinated cyclohexanes, a class of compounds that has not been previously produced. A synthesis of the all-syn-1,2,3,4-tetrafluorocyclohexane, in 9 steps from cyclohexa-1,3-diene will be presented. The ¹⁹F NMR spectra of the all-syn-1,2,3,4-tetrafluorocyclohexane shows interesting dynamic conformational effects. This is a small polar organic molecule, which was crystalline at room temperature. The structure of the compound was confirmed by single crystal X-ray diffraction studies. The synthesis of the all-syn-1,2,4,5-tetrafluorocyclohexane from cyclohexa-1,4-diene is also presented. The synthesis of a single diastereoisomer of 1,2,3,4,5,6-hexafluorocyclohexane, derived from benzene in 5 steps, is presented. As with the tetrafluoro compounds, the ¹⁹F NMR spectra of this compound shows dynamic conformational effects. The structure of the compound was confirmed by single crystal X-ray diffraction studies. The 1,2,4,5-tetrafluorocyclohexane motif was elaborated to contain a phenyl group, producing “rod-like” molecules. This motif was synthesised in view of potential applications for liquid crystalline materials.
6
Mpuhlu, Batsho. "Vapour phase dehydrogenation of cyclohexane on microstructured reactors". Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/8661.
Testo completoAbstract (sommario):
The work that is described in this thesis forms part of the research and development projects at InnoVenton: NMMU Institute of Chemical Technology in collaboration with Sasol Technologies. The broader view of the project was testing on the so-called “Small Production Platforms” (SPP’s). In particular the main aim of this study was to investigate the effect of micro-structuring on the heterogeneous catalysed, vapour-phase oxidative dehydrogenation of cyclohexane in the presence of air. Ground work studies were done to provide a proper comparison of the micro-structured reactor with a traditional fixed-bed reactor. These included evaluation of a proper vanadium pyrophosphate catalyst for the reaction, testing of reaction parameters for the oxidative dehydrogenation reaction on a fixed-bed reactor and lastly comparing the performance of the micro-structured reactor to that of the fixed-bed reactor Various vanadium pyrophosphate catalysts that were tested for activity included: bulk (VO)2P2O7, bulk (VO)2P2O7 promoted with Fe, (VO)2P2O7 supported on -Al2O3 and Fe promoted (VO)2P2O7 supported on -Al2O3. These catalysts showed significant differences in TOF, however it was not conclusive from the results whether these differences may be traced to increased activity for dehydrogenation for different catalysts since all reactions were run under conditions of oxygen deficiency. It is, however, clear that Fe promotion significantly increase activity, irrespective of the relative degrees of oxidative dehydrogenation and normal dehydrogenation. The Fe promoted catalyst was further tested for long term stability in-view of using it as the catalyst in the micro-structured reactor. These studies showed the catalyst to have a high degree of stability with minimal structural changes under the reaction conditions used. Various response surface models describing the variation in each of the cyclohexane conversion, cyclohexene selectivity, and benzene selectivity, respectively when changing reaction condition, were derived by means of multiple regression. To obtain some idea of the degree and nature of the normal dehydrogenation reaction, the amount of deficit oxygen was estimated from the measured results for cyclohexane conversion and cyclohexene and benzene selectivities. These estimated values were also modelled as described above. The regression models were used to interpret specific trends in the responses for the oxidative dehydrogenation of cyclohexane and account for the oxygen deficit in the system. The performance of a fixed bed tubular reactor (FBR) and micro-structured sandwich reactor (MSSR) were compared over an Fe promoted vanadium pyrophosphate. Reactor performance was evaluated by varying specific reaction conditions (temperature and space velocity). Subsequently the turn-over frequencies, conversion and selectivities from the two reactors were compared. The conversion achieved in the micro-structured reactor was observed to be significantly higher than that achieved in the fixed-bed reactor at all reaction parameters. This is despite the fact that the total amount of catalyst in the micro-structured reactor is approximately 5 times less than that used in the fixed bed reactor. In addition, the contact time (1/MHSV) in the micro-structured reactor is also significantly shorter than in the fixed-bed reactor.
7
Morin, Cynthia. "Étude de l'adsorption du cyclohexane et du cyclohexanone sur une surface polycristalline de carbure de molybdène, ß-Mo¦2C". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0016/MQ49040.pdf.
Testo completo
8
Trower, M. K. "The oxidation of cyclohexane by a Xanthobacter species". Thesis, Nottingham Trent University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356463.
Testo completo
9
Carcenac, Yvan. "Synthèse et étude de dérivés fluorés du cyclohexane". Versailles-St Quentin en Yvelines, 2005. http://www.theses.fr/2005VERS0042.
Testo completoAbstract (sommario):
La thèse présentée est une étude des équilibres conformationnels de cyc10hexanes 1,4¬disubstitués de stéréoisomérie cis, porteurs d'un groupement fluoré (CF3, C2Fs, CFH2, CF2H, OCF3 et SCF3) et d'un groupement alkyle ou aryle. Dans une première partie est abordée la synthèse des cyc10hexanes fluorés: Les composés porteurs des substituants trifluorométhyle, entafluoroéthyle et trifluorométhylthio ont été obtenus par utilisation de réactifs perfluorés. Les composés substitués par des groupements fluorométhyle, difluorométhyle et trifluorométhoxy ont été synthétisés par réactions de fluorations. La mise au point des différentes synthèses est décrite. Dans une seconde partie, les équilibres conformationnels de ces composés sont étudiés par RMN 19F à température variable. L'énergie nécessaire au passage des substituants de la position équatoriale à la position axiale nous permet d'évaluer les interactions stériques et électroniques des différents groupements avec leur environnement. Les effets des substituants sur les déplacements chimiques en RMN BC sont également commentésThe aim of this thesis was to study conformational equilibria of cis 1,4-disubstituted cyc1ohexanes, bearing a fluorinated group (CP3, C2Ps, CPH2, CP2H, OCP3 and SCP3) and an aIkyI or aryl group. Ln the first part of this manuscript, the synthe sis of fluorinated cyc10hexanes is described : compounds bearing trifluoromethyIe, pentafluoroethyIe or trifluoromethylthio. Substituents were obtained by the use of perfluorinated reagents, while compounds possessing a fluoromethyIe, difluoromethyle or trifluoromethoxy group were synthesized by fluorination reactions. The deveIopment ofthose various approches is described. Ln a second part, conformational analysis of these compounds was studied by 19p NMR at various temperature. The energy necessary for the passage of the substituents from the equatorial position to the axial position allowed us to evaluate the steric and electronic interactions of the different groups with their environment. The effects of the substituents on the chemical shifts in BC NMR are also commented
10
Razafitianamaharavo, Angelina. "Étude structurale du film de cyclohexane physisorbé sur graphite : Étude thermodynamique et structurale du film mixte (krypton-cyclohexane) physisorbe sur graphite". Nancy 1, 1989. http://www.theses.fr/1989NAN10080.
Testo completoAbstract (sommario):
La caractérisation structurale du cyclohexane adsorbe sur graphite a été effectuée entre 77**(O)K et 260**(O)K par diffraction de neutrons et de rayons X. Elle a permis de proposer un diagramme de phases 2D rendant compte de trois structures solides qui sont par ordre de densité croissante, commensurable, hexagonale incommensurable et rectangulaire centrée
11
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.
Testo completo
12
Cooper, James Arthur. "Novel cyclohexane-based receptors for anion binding and transport". Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.683940.
Testo completoAbstract (sommario):
This thesis describes a series of novel anionophores and details their synthesis, anion binding and anion transport capabilities. These novel anionophores are based on a cyclohexane scaffold CA, Figure 1), and are simpler to synthesise than the cholapod and decal ins CB and C in Figure 1 respectively) previously reported by the Davis group. Association constants for chloride were evaluated for the new cyclohexane-based receptors in DMSO-d6/0.S% H20 and, where solubility permitted, in water-saturated chloroform. For the novel cyclohexane systems A, higher association constants were obtained where R = Me as opposed to R = H as well as for those receptors possessing electron-deficient aromatics. However the association constants of these novel systems were found to be somewhat lower than those seen previously with cholapods and decalins. Anion transport by these new cyclohexanes was evaluated by the lucigenin method, with the majority of receptors displaying measurable anion transport activity. As with anion binding, higher levels of transport were obtained where R = Me as opposed to R = H and where aromatics were electron-deficient. Certain cyclohexane-based receptors were found to have similar or improved rates of transport when compared to previously reported receptors from the Davis group, including one which is the most active anion transporter reported by the Davis group. Some progress has also been made towards altering the identity of the hydrogen bond donors on the scaffold, further modifying appended alkyl units and a novel squaramide macrocycle.
13
Birtwistle, D. H. "Stereoselective routes to 1,2-disubstituted cyclohexanes". Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233426.
Testo completo
14
Aksnes, Dagfinn W., e Kjersti Førland. "Diffusion of cyclohexane and cyclopentane confined in mesoporous MCM-41". Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-196392.
Testo completo
15
Aksnes, Dagfinn W., e Kjersti Førland. "Diffusion of cyclohexane and cyclopentane confined in mesoporous MCM-41". Diffusion fundamentals 2 (2005) 81, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A14417.
Testo completo
16
Carr, C. A. "N.M.R. studies of mobile equilibria". Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379998.
Testo completo
17
Bacon, John. "Conformational analysis of cyclohexandiols and related compounds". Thesis, University of South Wales, 1987. https://pure.southwales.ac.uk/en/studentthesis/conformational-analysis-of-cyclohexandiols-and-related-compounds(d78175ac-be32-45a5-907a-892feb68c54d).html.
Testo completoAbstract (sommario):
The conformational equilibria in disubstituted cyclohexanes containing polar groups lead to a diversity of conformational forms. In solution, the conformational preference is shown to be highly dependent upon the nature of the solvent. In the cyclohexandiol series, the formation of intramolecular and intermolecular hydrogen bonds determines the conformational preference with regard to the molecule as a whole and with respect to the rotamer conformation of the hydroxyl groups. Polar solvents capable of hydrogen bonding to the hydroxyl group have been shown to influence the position of equilibrium between the alternative chair conformations. In cyclohexanol, the equilibrium is always shifted towards the equatorial conformation. 13C nmr, 1H nmr, solution i.r. and matrix isolation i.r. techniques have been used to determine the conformational structures in the cyclohexandiol series and the nature of the solvent interactions. Two types of solvent interaction have been identified, a hydrogen bonded interaction and a non-bonded dipole interaction. A Computer Graphic Simulation has been used to' quantify the conformational energy differences and to rationalize the experimental results in terms of the Van der Waals repulsion energy. The experimental results give strong evidence that in cis cyclohexan-1,3-diol, two types of internal hydrogen bond exist in the diaxial conformation. The Computer Graphic simulation supports this reasoning on thermodynamic grounds.
18
Alessi, Frédéric. "Synthèse d'analogues de l'acide 3-désoxy-D-érythro-2-hexulosonique, inducteur d'enzymes pectinolytiques chez la bactérie Erwinia chrysanthemi". Lyon 1, 1997. http://www.theses.fr/1997LYO10022.
Testo completoAbstract (sommario):
Le but de ce travail est l'etude de la reconnaissance entre la proteine represseur kdgr (proteine regulant la synthese des enzymes pectinolytiques chez la bacterie erwinia chrysanthemi) et le kdg (acide 3-desoxy-d-erythro-2-hexulosonique, inducteur de la biosynthese de ces enzymes). Afin de connaitre la plus petite unite structurale necessaire a cette reconnaissance nous avons synthetise plusieurs analogues du kdg. Deux syntheses precedemment mises au point dans notre equipe avaient permis l'acces au kdg totalement protege sauf en c-5 d'une part, et au kdg totalement protege sauf en c-4 d'autre part. A partir de la premiere molecule nous avons obtenus le 5-epi-kdg, le 5-o-benzoyl-5-epi-kdg et le 5-o-acetyl-5-epi-kdg, par triflation de l'hydroxyle libre ne c-5 puis substitution nucleophile par un anion carboxylate, le 5-desoxy-kdg, par triflation de l'hydroxyle en c-5 puis substitution nucleophile par un iodure et hydrogenolyse, le 5-o-benzoyl-kdg et le 5-o-mesitoyl-kdg, par esterification de l'hydroxyle en c-5. Le 4-o-methyl-kdg a ete synthetise par methylation du kdg totalement protege sauf en c-4, et le 4-desoxy-kdg, a ete obtenu par condensation de wittig entre le 2,3-o-isopropylidene-d-glyceraldehyde et le formylmethylenetriphenylphosphorane. Les pyranosides de methyle du 5-o-methyl-kdg ont ete obtenus par glycosylation de fisher. Enfin, un des analogues cyclohexanique du kdg a ete obtenu par une sequence dont l'etape cle est la cyclisation radicalaire 6-exo-dig d'un iodoalcyne trimethylsilyle. Les tests biochimiques effectues sur ces molecules ont montres que l'oh en c-5 ne participe pas a la reconnaissance, par contre les oh en c-2 et c-4 ainsi que l'oxygene intracyclique sont indispensables a cette reconnaissance.
19
Pinvidic, Jean-Jacques. "Calorimétrie adiabatique : construction et automatisation : application aux cristaux vitreux". Paris 11, 1988. http://www.theses.fr/1988PA112249.
Testo completo
20
Sadiki, Mustapha. "Etude des effets coopératifs entre les ions métalliques et les hydrocarbures à l'interface eau-air : Impact sur l'environnement". Brest, 2005. http://www.theses.fr/2005BRES2008.
Testo completoAbstract (sommario):
Dans cette thèse ont été étudiées, à l'interface air-eau, l'adsorption du benzène et du cyclohexane à partir d'une solution aqueuse d'une part, et la coadsorption du nitrate de plomb à partir de mélanges hydrocarbure-eau d'autre part. Deux techniques ont été utilisées : la tensiométrie pour les solutions concentrées et, pour les solutions diluées, la colonne à bulles : cette dernière a été montée au laboratoire à l'occasion de la thèse, et utilisée pour la première fois pour une étude originale. La présence d'hydrocarbure dans la couche d'adsorption induit la coadsorption du sel métallique. L'influence des concentrations et de la nature de l'hydrocarbure est discutée. Le phénomène de coadsorption mis en évidence au laboratoire existe potentiellement dans l'environnement, et pourrait expliquer le passage des métaux lourds depuis des nappes aqueuses jusqu'à l'atmosphère au travers d'un processus de pétillementBenzene and cyclohexane adsorption, at the air-water interface, from aqueous solutions, and lead nitrate coadsorption from hydrocarbon-water mixtures have been studied by two different methods. Tensiometry has been used for concentrated solutions. For diluted ones, a bubble column has been constructed, standardized and used for the first time in an original study. Hydrocarbon presence in the adsorption layer induces the coadsorption of lead salt. The role of concentrations and hydrocarbon nature is discussed. Coadsorption phenomenon may exist in environment and could explain the passing of heavy metal salts from aqueous sheets to atmosphere through a bubbling phenomenon
21
Frid, Henrik. "Simulation of Microbubbles during the Initial Stages of Breakdown in Cyclohexane". Thesis, KTH, Fysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-129399.
Testo completoAbstract (sommario):
The formation of a vapor microbubble has previously been suggested to be the initial mechanism in the process of dielectric failure of dielectric liquids. The bubble is generated by a rapid, highly localized heating of a volume close to a highly stressed electrode, caused by electric currents in the liquid at high voltages. In this paper, a numerical model is presented to investigate the dynamics of a single microbubble in a point-plane geometry in cyclohexane. A condition for the formation of a vapor bubble is discussed. Thereafter, a Computational Fluid Dynamics (CFD) model of two-phase flow with phase transition is used to study the dynamics of the bubble from generation to collapse, under a highly divergent electrostatic field in a subcooled liquid. The amount of subcooling in the simulations is 5 K, and it is found that convergence gets significantly weaker as the amount of subcooling increases. The bubble expansion is also simulated considering the electrohydrodynamic (EHD) processes in the liquid and vapor phases. Finally, it is shown how the electrostatic forces on the dielectric will cause a bubble to detach from the electrode. Index Terms —Dielectric failure, streamer initiation, bubble dynamics, electrohydrodynamics, computational fluid dynamics
22
Belkhir, Inès. "Rôle de tamis moléculaires dans l'oxydation du cyclohexane en acide adipique". Montpellier 2, 1997. http://www.theses.fr/1997MON20161.
Testo completoAbstract (sommario):
L'etude de la catalyse d'oxydation du cyclohexane en acide adipique a ete realisee en presence de tamis moleculaires contenant du cobalt ou du manganese. Differents types de materiaux ont ete prepares, soit par echange cationique, soit par depot d'oxydes ou par insertion du cation de transition dans le reseau zeolithique. L'utilisation de ces tamis moleculaires pour l'oxydation du cyclohexane en acide adipique dans l'acide acetique n'a toujours conduit qu'a une catalyse homogene provenant d'une faible dissolution du cation metallique dans le milieu reactionnel. Elle a permis de mettre en evidence un phenomene de conversion du catalyseur en inhibiteur qui n'avait, jusqu'a present, ete observee qu'en milieu peu polaire. L'encapsulation de perfluorophtalocyanines de cobalt dans des zeolithes a aussi ete effectuee. Dans ce cas, les solides obtenus sont stables dans le milieu reactionnel, mais ne catalysent pas l'oxydation du cyclohexane.
23
Haidara, Modibo. "Impulsions de Trichel dans le cyclohexane liquide et les gaz comprimés". Grenoble 1, 1988. http://www.theses.fr/1988GRE10160.
Testo completoAbstract (sommario):
Resultats d'etude de la conduction electrique de liquides non polaires tres purs (cyclohexane, n-propane) en geometrie pointe-plan, en fonction du rayon de courbure de la pointe et de la pression hydrostatique (p<->10**(7)pa)
24
Haidara, Modibo. "Impulsions de Trichel dans le cyclohexane liquide et les gaz comprimés". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37614184p.
Testo completo
25
Yeung, Bik Wah Anissa. "Methylenecyclohexane annulations : total syntheses of axane-type sesquiterpenoids". Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/27655.
Testo completoAbstract (sommario):
This thesis describes the preparation of 5-chloro-2-trimethyl-stannyl-1-pentene (111) and its conversion into 5-chloro-2-lithio-1-pentene (112). The latter reagent, which reacts smoothly with cyclohex-anone at -78°C to give 5-chloro-2-(1-hydroxycyclohexyl)-1-pentene (132), was found to be thermally unstable at temperatures higher than -63°C.
Reagent (112) was transformed into the Grignard reagent (144) and the organocopper-phosphine complex reagent (145). Conjugate addition of reagents (144) and/or (145) to cyclic enones under appropriate conditions followed by cyclization of the resultant products, effected useful methylenecyclohexane annulation sequences [(104) → (116)].
This methylenecyclohexane annulation method served as one of the two key steps in the syntheses of (±)-axamide-1 (174), (±)-axiso-nitrile-1 (173), and the corresponding C-10 epimers. Thus, copper(I)-catalyzed addition of the Grignard reagent (144) to 2-methyl-2-cyclo-penten-1-one (152), followed by cyclization of the resultant chloro ketone (159), gave the annulation product (170), which was converted into the enone (203). The other key step in the projected synthesis, which involved TiC1₄-catalyzed conjugate addition of the bis(trimethyl-silyl) ketene acetal (226) to the enone (203), provided a mixture of the keto acids (222) and (223). With appropriate functional group manipulations,
(222) was converted into (±)-axamide-1 (174) and (±)-axisonitrile (173), while (223) was converted into (±)-10-epi-axamide-1 (224) and (±)-10-epi-axisonitrile-1 (225). [Formula Omitted]Science, Faculty of
Chemistry, Department of
Graduate
26
Domínguez, Pérez Beatriz. "Rational design and synthesis of new nucleoside analogues bearing a cyclohexane core". Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/300747.
Testo completoAbstract (sommario):
L’ús d’anàlegs de nucleòsids en teràpia antivírica s’ha convertit en una opció important durant les tres últimes dècades. En els últims anys, l’atenció s’ha centrat en els carbanucleòsids, que són més resistents als processos hidrolítics i tenen una millor absorció i penetració a través de la membrana cel·lular com a resultat de la seva major lipofília. Els anàlegs de nucleòsids amb estructura ciclohexènica són una classe prometedora de compostos antiviral, en què la substitució de l’àtom d’oxigen de l’anell de furanosa per un doble enllaç indueix una flexibilitat anul·lar similar a la dels nucleòsids naturals. Recentment, s’ha descrit que ambdós enantiòmers de ciclohexenil G (DCG i LCG) presenten una potent i selectiva activitat contra el virus de l’herpes.
D’altra banda, les tècniques de modelatge molecular han estat una de les pedres angulars en el disseny i optimització de compostos terapèutics. Concretament, les tècniques d'acoblament molecular (docking), que s'utilitzen per predir l'afinitat d'unió d'una molècula orgànica a una macromolècula, han demostrat ser una eina de molta utilitat. En el camp d’anàlegs de nucleòsids, aquestes tècniques permeten simular tant el seu procés d'activació, així com la posterior interacció amb la seva diana, la polimerasa viral corresponent.
Aquesta tesi es centra en el disseny racional i la síntesi d'una sèrie de nucleòsids carbocíclics de sis baules basats en l'esquelet de D- i L-Ciclohexenil G com a agents contra el virus de l’herpes. En particular, s'ha dut a terme un estudi de modelatge molecular de tot el procés d'activació d’una sèrie de nucleòsids ciclohexànics i biciclo[4.1.0]heptànics per mitjà de càlculs de docking. Com a resultat d’aquest estudi computacional, vam decidir desenvolupar un nova estratègia sintètica cap a la síntesi estereoselectiva d'anàlegs de nucleòsids amb estructura biciclo[4.1.0]heptànica. En concret, s’han sintetitzat quatre nous nucleòsids amb estructura biciclo[4.1.0]heptànica que contenen diferents bases púriques i pirimidíniques, a partir de la 1,4-ciclohexandiona comercial en 14-16 etapes i rendiments globals d’entre el 2% i el 10%. A més a més, s’ha descrit un nou procediment per la síntesi de (2R,3R,8R)-2,3-difenil-1,4-dioxaespiro[4.5]deca-6-en-8-ol, que és un intermedi de la síntesis d’aquests anàlegs de nucleòsids, juntament amb la síntesi enantioselectiva d’ambdós enantiòmers de la (4R)-hidroxi-2-ciclohexenona i els seus derivats sililats. Aquests procediments competeixen positivament amb les metodologies publicades. L'activitat biològica dels compostos sintetitzats contra diversos virus ha estat avaluada. Per desgràcia, no mostren activitat antivírica significativa. Per tal de racionalitzar aquesta manca d'activitat, la interacció dels fàrmacs candidats amb la seva diana ha estat avaluada. Com que no hi ha estructures cristal·logràfiques del procés de replicació, s’ha generat un model en 3D per mitjà del modelatge d’homologia. Aquesta metodologia permet la predicció d’estructures en 3D de macromolècules basades en estructures conegudes de proteines homólogues (plantilles). Els càlculs han revelat que l’activitat antivírica d’aquests compostos està restringida per la seva incorporació al DNA del virus.The application of nucleoside analogues in antiviral therapy has evolved into an important option over the last three decades. In recent years, attention has been focused on carbanucleosides, which are more resistant to hydrolytic processes and have better absorption and penetration through the cell membrane as a result of their higher lipophilicity. Cyclohexenyl nucleosides are a promising class of antiviral compounds, wherein replacement of the oxygen atom of the furanose ring by a double bond induces annular flexibility, similar to that of regular nucleosides. Recently, it has been described that both enantiomers of cyclohexenyl G (DCG and LCG) display potent and selective anti-herpes virus activity. On the other hand, molecular modelling techniques have been one of the cornerstones in the design and optimization of novel therapeutic agents. Specifically, molecular docking techniques, which are used to predict the binding affinity of an organic molecule to a macromolecule, have become a useful tool. In the field of nucleoside analogues, docking techniques may be applied to simulate both their activation process as well as their interaction with their target, the corresponding viral polymerase. The present thesis is focused on the rational design and synthesis of a series of six-membered carbocyclic nucleosides based on the skeleton of D- and L-Cyclohexenyl G as anti-herpes virus agents. In particular, a molecular modelling study on the whole activation process of a set of cyclohexene and bicyclo[4.1.0]heptane c nucleosides has been carried out by means of protein-ligand docking calculations. As a result of the computational study, we decided to develop a new synthetic strategy towards the stereoselective synthesis of nucleoside analogues with a bicyclo[4.1.0]heptane structure. Specifically, it has been synthesised four novel bicyclo[4.1.0]heptane nucleosides bearing different purine and pyrimidine bases, starting from 1,4-cyclohexanedione in 14-16 steps and overall yields between 2% and 10%. In addition, it has been described a new procedure to synthesise (2R,3R,8R)-2,3-diphenyl-1,4-dioxaspiro[4.5]decan-6-ene-8-ol, which is an intermediate for the synthesis of these nucleoside analogues, along with the enantioselective synthesis of both enantiomers of (4R)-hydroxy-2-cyclohexenone and their O-silyl derivatives. These procedures compete positively with the published methodologies. The biological activity of the synthesised analogues against several viruses has been evaluated, although none of them displayed significant activity. In order to rationalise this lack of activity, the interaction of the drug candidates with their target has been evaluated. As there is no crystallographic structure of the replication process, a 3D model has been generated by means of a homology modelling like approach. This methodology allows the prediction of 3D structures of macromolecules based on known structures of homologous proteins (templates). The theoretical calculations have revealed that the antiviral activity of these candidates is restricted by their incorporation into the viral DNA.
27
Forlines, Robert Alan. "Laser Initiated Chain Reactions: The Kinetics of the Chlorine/Cyclohexane/Oxygen Chain System". Wright State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=wright1182792546.
Testo completo
28
Rotella, David Paul. "The synthon concept in medicinal chemistry : synthesis and applications of cyclohexane diol diamines /". The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487263399027046.
Testo completo
29
Tang, Jie. "Mesure de l'anomalie critique de l'indice de réfraction du mélange binaire nitroéthane-cyclohexane". Thèse, Université du Québec à Trois-Rivières, 1993. http://depot-e.uqtr.ca/5304/1/000601258.pdf.
Testo completo
30
Cheney, Matthew A. "Synthesis, resolution, and diastereoselectivity of the chiral auxiliary trans-2-(9H-flouren-9-yl)cyclohexanol". To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2007. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
Testo completo
31
Cooper, Elaine. "Infrared studies of hydrocarbon adsorption on Ni{111}". Thesis, University of Aberdeen, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296514.
Testo completoAbstract (sommario):
Reflection-absorption infrared spectroscopy (RAIRS) has been used to probe the interaction of cyclohexane, partially deuterated cyclohexane C6HD11, toluene and ethylene with the Ni{111} surface. The coadsorption of cyclohexane and oxygen on the Ni{111} surface has also been studied in some detail; the effects of differing coverages of both pre- and post- dosed oxygen on cyclohexane adsorption has been investigated. As these experiments were the first to be completed using a new UHV system, an important element of this PhD project involved commissioning the UHV system, including the LEED and Auger apparatus, and setting up the RAIRS optical system. On the clean Ni{111} surface at 110 K adsorbed cyclohexane exhibits a site symmetry of C3v which persists through to the multilayer regime. Adsorbed molecules in the first layer exhibit a broadened and downshifted vCh stretching vibrational band, thought to arise from CH...M interactions and observed on many metal single crystal surfaces. The effect of coadsorbed oxygen on cyclohexane adsorption is strongly coverage dependent. At lower oxygen coverages, θO ≤ 0.25, a further downshifting of the softened vCH stretching vibration is observed, indicating the importance of charge transfer from the filled CHσ orbital to the metal in weakening the C-H bond. Adsorption of cyclohexane on the Ni{111}-(√3x√3)R30°-O surface, θO = 0.33, leads to total suppression of any C-H...M interaction, attributed to blocking of the bare metal sites by the adsorbed atoms. Post-dosing of oxygen on the cyclohexane adlayer leads to compression of existing islands of cyclohexane, involving molecular transfer from the first layer to the second. This is attributed to the difference in heats of adsorption of the two adsorbates.
32
Compain, Philippe. "Réarrangement thermique d'α-hydroxyimines scalémiques : approche synthétique du squelette 1-azaspiro[5,5]undécane : synthèse de γ-butyrolactones catalysée par des sels de palladium(II)". Lyon 1, 1997. http://www.theses.fr/1997LYO10120.
Testo completoAbstract (sommario):
L'histrionicotoxine est l'un des membres d'une famille d'alcaloides isoles a partir des secretions de grenouilles arboricoles colombiennes, les dendrobates histrionicus. Les proprietes biologiques uniques de l'histrionicotoxine, ainsi que de son analogue hydrogene la perhydrohistrionicotoxine, en font des outils de choix pour l'etude des recepteurs cholinergiques du systeme neuromusculaire. Dans le but de realiser une approche synthetique des histrionicotoxines, nous avons entame une etude sur le rearrangement thermique d'alpha-hydroxyimines scalemiques avec migration 1,2 d'un groupement allylique ou propargylique. Dans un premier temps, nous avons pu mettre en evidence un transfert de chiralite de type 1,2 en serie cyclohexanique et generer le carbone quaternaire azaspiranique des histrionicotoxines de facon enantiopure. La determination de la configuration absolue du nouveau centre stereogenique forme nous a permis de demontrer que la transposition etait suprafaciale. Dans un deuxieme temps, a partir des alpha-aminocyclohexanones enantiopures obtenues par rearrangement thermique, nous avons imagine une voie de synthese generale de la (-)-histrionicotoxine. Les differentes etudes menees ont permis de realiser une synthese formelle de la (-)-perhydrohistrionicotoxine. Enfin, lors de nos recherches d'une voie de synthese efficace d'alpha-hydroxyimines enantiopures, nous avons mis en evidence une nouvelle voie d'acces aux gamma-butyrolactones, catalysee par des sels de palladium (ii), a partir de 4-trimethylsilyl-3-alcyn-1-ols. Un mecanisme de cette cyclisation a egalement ete propose et confirme par une etude experimentale. La synthese rapide d'une spirolactone bioactive en serie steroide a permis de souligner l'interet synthetique de cette nouvelle methodologie.
33
Nasar, Kamel. "Synthèse de composés cyclohexyles optiquement actifs par réduction énantio- et dia-stéréosélective de noyaux aromatiques polysubstitués en catalyse hétérogène". Lyon 1, 1994. http://www.theses.fr/1994LYO10255.
Testo completoAbstract (sommario):
Un effort de recherche considerable est actuellement mis en uvre pour etablir des methodes generales de synthese de molecules biologiquement actives. La catalyse homogene, et plus recemment quelques systemes catalytiques heterogenes, ont prouve leur efficacite en hydrogenation de cetones ou d'olefines prochirales. Mais l'hydrogenation d'aromatiques substitues en derives cyclohexyles optiquement actifs n'a jusqu'ici jamais ete realisee par catalyse homogene ou heterogene. Nous avons aborde deux approches differentes pour traiter ce sujet: la reduction enantioselective par du rhodium colloidal stabilise par des amines chirales agissant comme inducteurs dans les systemes biphasiques ; la reduction diastereoselective utilisant le meme processus de catalyse par les colloides de rhodium ou par du rh/c avec ou sans additifs amines. Les reductions enantioselectives sur les derives de l'ortho-cresol ont conduit a des exces enantiomeriques (ee) de 3 a 6%. Ces ee bien que faibles sont neanmoins significatifs et constituent, a notre connaissance, les premiers exemples de reduction asymetrique de composes disubstitues par catalyse heterogene. Les resultats obtenus par reduction diastereoselective ont ete plus probants. En effet, un exces diastereoisomerique de plus de 60% a ete obtenu pour l'hydrogenation du 1-(2-methylbenzoyl)2-(methylester)-(s)-prolinamide catalysee par le rh/c dans l'ethanol en presence de la (-)-di-n-octylcyclohexyl-1-ethylamine, amine tres encombree. L'effet de differents parametres a ete etudie dans cette reaction
34
Zhang, Zichen. "Anticancer effects of hexamethylene bisacetamide on human colon carcinoma cells in vitro /". Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21021065.
Testo completo
35
Ajo, Henry. "Energetics of hydrocarbon adsorption on model catalysts /". Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/8486.
Testo completo
36
Lebedeva, Anastasia. "Nanomatériaux à base de ruthénium et de manganèse pour l'oxydation catalytique d'hydrocarbures dans l'eau". Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S099/document.
Testo completoAbstract (sommario):
L'activation de la liaison Csp3-H peu réactive et sa fonctionnalisation en liaison carbone-hétéroatome constituent un défi pour les chimistes de synthèse. Un exemple d'intérêt industriel est la réaction d'oxydation du cyclohexane, dont les produits finaux (cétone et alcool) sont des intermédiaire clés pour la production de polyamides tels que les Nylon-6 et 6,6. Parmi les possibilités d'activation, la catalyse représente une méthode de choix. Dans le cadre de cette thèse des suspensions aqueuses à base de nanoparticules ont été évaluées en termes de stabilité et de performances catalytiques. Dans un premier temps, des colloïdes de ruthénium ont été synthétisés à partir de RuCl3,3H2O et caractérisés par des analyses physico-chimiques (MET, SPX, SAXS, UV-visible, etc.). Des espèces actives de Ru+3 dont la structure est de type Ru(OH)3-xClx ont été obtenues. Après optimisation des conditions de réaction, des conversions élevées, associées à des sélectivités pertinentes vis-à-vis de la cétone (jusqu'à 98%), ont été obtenues. Des études cinétiques et mécanistiques ont montré que la voie radicalaire est prépondérante. De plus, ces colloïdes de Ru aisément recyclables ont également été testés avec succès en oxydation d'autres hydrocarbures saturés et insaturés. Dans un second temps, un catalyseur à base de dioxyde de manganèse, métal moins coûteux et abondant, a été synthétisé par un procédé redox original, à partir de KMnO4 et en présence d'un ammonium quaternaire à tête polaire hydroxylée (HEA16Cl), qui joue simultanément le rôle de réducteur et d'agent stabilisant. Ce système s'est révélé être une alternative pertinente aux procédés à base de métaux nobles. Les nanobâtonnets de MnO2 se sont ainsi montrés actifs en oxydation du cyclooctane avec une sélectivité totale en cétoneThe activation of the Csp3-H bond and its transformation into a carbon-heteroatom bond remains a great challenge for the organic chemistry. An example of industrial application is the oxidation reaction of cyclohexane, leading to the production of the corresponding ketone and alcohol, key intermediates of Nylon-6 and Nylon-6,6 polyamides. Among the strategies to activate this unreactive bond, catalysis affords a relevant and sustainable tool. In this work, aqueous suspensions of metal nanoparticles were evaluated in terms of their stability and catalytic performances. Firstly, ruthenium colloids were synthesized from RuCl3.3H2O and fully characterized by various physico-chemical analyses (TEM, XPS, SAXS, UV-visible, etc.). Ru+3 active species were obtained, with a Ru(OH)3-xClx structure. After optimization of the reaction conditions, high conversions, combined with pertinent selectivities towards the ketone (up to 98%), were achieved. The presence of radical species was proved through kinetic and mechanistic studies. Furthermore, these easily recyclable Ru colloids were also evaluated in the oxidation of several saturated and unsaturated hydrocarbons. Secondly, a catalyst based on manganese dioxide, a cheap and abundant metal, was synthesized by an original redox process, starting from KMnO4 and in the presence of a hydroxylated quaternary ammonium (HEA16Cl), which plays the role of a reducing and stabilizing agent. This system proved to be a relevant alternative to methodologies based on noble metals. The MnO2 nanorods showed a good activity in the cyclooctane oxidation with a 100% selectivity towards the ketone
37
Fischer, Johannes. "Reaktions- und sicherheitstechnische Untersuchung der partiellen Autoxidation von Cyclohexan in Mikrostrukturen". Doctoral thesis, Universitätsbibliothek Chemnitz, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-70031.
Testo completoAbstract (sommario):
In dieser Arbeit wird die partielle Autoxidation von Cyclohexan zu Cyclohexanol und Cyclohexanon mit Luftsauerstoff in einem Kapillarrohrreaktor untersucht. Gegenüber dem konventionellen Verfahren wurde die Temperatur auf 180-250°C und der Druck auf 20-80 bar angehoben. Auf diese Weise konnte eine Steigerung der Raum-Zeit-Ausbeute um etwa den Faktor 200 (von 25 kg/m³*h auf ca. 6000 kg/m³*h) erreicht werden. Die Umsätze sind dabei denen der industriellen Anlage vergleichbar. Die Selektivität der partiellen Oxidation zu den Wertprodukten cyclohexanol, Cyclohexanon und Cyclohexylhydroperoxid liegt im Kapillarrohrreaktor mit 80-90 % etwas unter den in der industriellen Anlage erreichbaren Selektivität von ca. 90-95 %. Die Reaktion im Kapillarrohrreaktor wurde auch aus sicherheitstechnischer Perspektive untersucht. Cyclohexan ist in die Explosionsgruppe IIA eingeordnet. Um das System in konservativer Weise zu betrachten, wurde als Stoffsystem Ethen (Referenzgas der Explosionsgruppe IIB) im Gemisch mit Sauerstoff bzw. Lachgas ausgewählt. Es wurde ein Versuchsaufbau konstruiert, mit dem ex möglich war stabile Detonationen zu erzeugen, diese in die Mikrostruktur einzuleiten und deren Ausbreitung und ggf. Austritt aus der Mikrostruktur zu beobachten. Im Versuchsprogramm wurde der Anfangsdruck im Bereich von 0,1 bis 10 bar und der Rohrdruchmesser der eingesetzten Kapillarrohr im Bereich von 0,13 - 1 mm variiert. Es zeigt sich, dass sich stabile Detonationen von stöchiometrischen Ethen/Sauerstoff-Gemischen bei einem Anfangsdruck von 1 bar abs gerade noch durch eine Kapillare mit einem Innendurchmesser von 0,13 mm ausbreiten können. Es wurde aus den Messdaten und theoretischen Betrachtungen eine Kennzahl für die Bewertung von Mikrostrukturierten Bauteilen entwickelt und diskutiert: der maximale sichere RohrdurchmesserIn this thesis a process is described for the uncatalyzed selective oxidation of cyclohexane with air at high-p, T-conditions in a micro capillary reactor. At 533 K a spacetime-yield of about 6000 kg/(m3 ? h) is reached, which corresponds to a size of 2 m x 2 m x 2 m(8 m3) of the microstructured reactor assuming a capacity of 100000 t/a compared to 500 m3 total reactor volume realized with a cascade of bubble columns of each about 100 m3. Unfortunately, selectivity drops at this temperature below 80 % which is significantly lower than the selectivity in the conventional process. With the help of the Hatta number, mass transfer limitations can be excluded for the micro capillary reactor, whereas the bubble column reactor is weakly limited by the gas/liquid mass transfer of the molecular oxygen. Thus, process intensification by enhancing mass transfer using a microstructured reactor for cyclohexane oxidation with air is quite low. Furthermore a method and its corresponding results are presented for the determination of maximum safe capillary diameters, which may be used to describe the extended range of safe operation conditions for gas phase oxidation reactions in microstructured reactor devices. Sections of stainless steel micro capillaries of different inner diameters are mounted between a primary and a secondary chamber. An explosion is ignited in the primary chamber, where also a deflagration to detonation transition occurs. The propagation of the detonation through the stainless steel micro capillaries is monitored by pressure transducers located between the sections of the micro capillaries. This setup is used in order to determine explosion velocities inside the capillaries, maximum safe initial pressures and corresponding maximum safe capillary diameters. Initial investigations are performed with an ideal stoichiometric mixture necessary for complete combustion of ethene with oxygen respectively ethene and nitrous oxide at room temperature. The measured maximum safe capillary diameters obey an indirect proportionality to the initial pressures. The maximum safe capillary diameter can be estimated on the basis of the lambda/3-rule
38
Flores, Ferrándiz Jesús. "Chiral Aminocarbamates Derived from trans-Cyclohexane-1,2-Diamines as Organocatalysts in Conjugate Addition Reactions". Doctoral thesis, Universidad de Alicante, 2017. http://hdl.handle.net/10045/73589.
Testo completoAbstract (sommario):
The thesis has been divided in two chapters: Chapter I describes the preparation of primary-amine monocarbamates from enantiopure trans-cyclohexane-1,2-diamines and their use as chiral organocatalysts in the enantioselective Michael addition reaction of aldehydes and ketones to maleimides, to synthesize enantiomerically enriched substituted succinimides. In the conjugate addition reaction of aldehydes to maleimides in conventional volatile organic solvents, it has been found that these organocatalysts are able to generate both enantiomers of the corresponding succinimide using only one enantiomeric form of the catalyst, just by changing the polarity of the solvent. Theoretical calculations justify the mechanism through which this inversion of enantioinduction occurred. In addition, these organocatalysts were used in the enantioselective Michael addition reaction of aldehydes to maleimides, using Deep Eutectic Solvents (DES) as recyclable and environmentally sustainable reaction medium, yielding the corresponding succinimides with excellent yields and high enantioselectivities (up to 94%). The succinimides can be extracted from the DES, which retains the chiral organocatalyst, allowing to reuse both solvent and catalyst. Moreover, the conjugate addition of ketones to maleimides using conventional solvents, allows obtaining the corresponding succinimides with excellent yields but with moderate enantioselectivities (up to 66%). Chapter II shows the results obtained in the enantioselective Michael addition reaction of aldehydes and ketones to nitroalkenes, using the former trans-cyclohexane-1,2-diamine-derived aminocarbamates as chiral organocatalysts, obtaining enantioenriched γ-nitrocarbonyl compounds. In the conjugate addition of isobutyraldehyde to nitroalkenes, the corresponding γ-nitroaldehydes were obtained with enantioselectivities up to 84%. In addition, the enantioselective conjugate addition reaction of ketones to nitroalkenes allowed to obtain interesting γ-nitroketones with high enantioselectivities (up to 96%). Theoretical calculations justify the mechanism involved during this enantioselective process.
39
Manaa, Chadlia. "Influence du désordre sur les propriétés opto-électroniques de films minces de cyclohexane déposés par polymérisation plasma". Thesis, Amiens, 2015. http://www.theses.fr/2015AMIE0001/document.
Testo completoAbstract (sommario):
Dans ce travail avons mis en évidence l’influence de la puissance radio-fréquence (RF) sur les différentes propriétés microstructurales, optiques, électriques, paramagnétiques ainsi que la morphologie des films minces polymérisés par PECVD capacitive, en utilisant la vapeur du cyclohexane comme précurseur.A faible puissance RF les surfaces de nos films sont poreuses et fortement hydrogénées. Elles possèdent un caractère hydrophile. L’augmentation de la puissance RF (à partir de 120 W) engendre une microstructure moins hydrogénée des couches et favorise les réarrangements atomiques entre les atomes de carbone et notamment, la formation de liaisons de type C=C (C-sp²). Dans cette gamme de puissance nous avons réussi à augmenter le caractère conducteur de nos films polymérisés. Ces résultats sont en bon accord avec les mesures optiques qui montrent qu'à forte puissance RF les films obtenus sont plus durs (augmentation de n avec la puissance) et leur gap optique est de plus en plus faible. Cette diminution du gap optique a été interprétée en termes de distorsions, de graphitisation et de réorganisation des sites C-sp2 pour former des amas plus grands et mieux organisés. Il apparaît, en combinant ces mesures avec celles obtenues sur la microstructure (Raman et Infrarouge), que l’augmentation de la conductivité électrique et la diminution du gap optique correspondent à une augmentation du nombre des doubles liaisons C=C, c’est-à-dire, une « graphitisation » du film favorisant ainsi le caractère conducteur.Néanmoins, la conductivité électrique reste faible, ce qui est expliqué par les mesures de résonance paramagnétique électronique (RPE), qui montrent qu’il existe des défauts au sein des sites C-sp2 et que la densité de spins augmente avec la puissance RF, indiquant que la densité de défauts augmente dans les films minces déposés à forte puissance RF. De plus le rétrécissement des raies RPE lorsque la puissance RF augmente, indique la diminution de l’interaction d’échange entre les spins suite à leur délocalisation dans les structures des liaisonsIn this work we have shown the influence of the radio frequency (RF) power on the microstructural, optical, electrical, electronic and morphological properties of thin films polymerized by capacitive PECVD using cyclohexane as precursor gas.At low RF power, the surfaces of our films are porous and highly hydrogenated. They have a hydrophilic character. The increase in the RF power (above 120 W) generates less hydrogenated microstructure and promotes atomic rearrangements between the carbon atoms, including the formation of C = C (C-sp²) bonds. In this RF power range we observed an increase of the conductor character of our polymerized films. These results are in good agreement with optical measurements, show that high RF power induces harder deposited films (increase of n with RF power) and a decrease in the optical gap. This decrease in the optical gap was interpreted in terms of distortions, graphitization and reorganization of the C-sp2 sites, which form larger and better organized clusters. It appears, by combining these measurements with those obtained on the microstructure (Raman and FTIR), that the increase in the electrical conductivity and the decrease of the optical gap is associated with the increase in the number of C = C double bonds, that is to say a "graphitization" of the film, promoting the conductive nature.However, the electrical conductivity values are still a little low, which is explained by the electron paramagnetic resonance (EPR) measurements, which showed the presence of defects within the C-sp2 sites, and that the spin density increases with RF power, suggesting an increase in the defect density in the thin films deposited at high RF power. Furthermore, the narrowing of the EPR lines when the RF power increases indicates a decrease in the exchange interaction between spins as a result of delocalization phenomena in the bond structures
40
Gueudré, Laurent. "Diffusion du cyclohexane dans la Silicalite-1 : Origine et caractérisation de la résistance de surface". Lyon, Ecole normale supérieure, 2010. http://www.theses.fr/2010ENSL0580.
Testo completoAbstract (sommario):
L’objectif de ce travail est d’étudier plus en détail la résistance au transfert de matière à la surface des solides microporeux, en mesurant les cinétiques d’adsorption sur le système cyclohexane/Silicalite-1 par thermogravimétrie. Afin de réaliser cette thèse, un soin particulier a été accordé à la synthèse de cristaux de Silicalite-1 de différentes tailles afin de dissocier la résistance de surface de la résistance diffusionnelle intracristalline. Ces synthèses ont été réalisées de manière à obtenir des cristaux de géométrie quasi sphérique et possédant une répartition de taille homogène. Le montage expérimental utilisé lors de ces travaux nous a permis d’obtenir des courbes de cinétiques de prise et de perte de masse dans différentes conditions de température, de pression partielle et pour ces cristaux de tailles différentes. Celui-ci est principalement constitué d’un saturateur permettant de vaporiser un adsorbat liquide à une pression partielle déterminée et d’une thermobalance composée de deux fours, l’un servant de référence et l’autre accueillant les échantillons. Bien que cette méthode expérimentale soit simple de part son principe, son utilisation s’est montrée particulièrement délicate du fait des très faibles variations de masse mesurées. Les résultats ont ensuite été exploités à l'aide d’un modèle tenant compte de la variation de diffusivité intracristalline avec le taux de remplissage et d’une résistance de surface représentée par un modèle de film situé dans le cristal. Les résultats expérimentaux nous ont permis de définir deux types de résistance de surface distincts, que nous avons nommée "résistance native" et "résistance évolutive". La première est présente dès la synthèse des cristaux, tandis que l’autre est dépendante de l’historique et de la méthode de synthèse des échantillons. La résistance évolutive peut être fortement réduite en lavant la surface des cristaux avec des solutions d'acide fluorhydrique, ce qui n'est pas le cas pour la surface native. En étudiant l'influence de différentes conditions opératoires (température, concentration, comparaison adsorption/désorption), nous avons pu proposer un mécanisme pour le transfert de matière à la surface des cristaux : les molécules s’adsorberaient sur la surface des cristaux depuis la phase fluide en suivant une isotherme d’adsorption favorable. L’adsorbat serait ensuite libre de diffuser sur la surface, avant de pénétrer dans les poresThe aim of this work is to study cyclohexane transfer resistance at the surface of Silicalite-1 crystals. To do so, cyclohexane uptake curves were performed on Silicalite-1 crystals using a classical gravimetric technique. In order to dissociate surface and microporous resistances, the experiments were performed on a wide range of crystals sizes. First of all, Silicalite-1 crystals of different sizes were synthesized. The synthesis conditions were optimized so as to obtain crystals of different sizes, quasi spherical, homogeneous in size. Next, uptake curves were recorded in different operating conditions, such as temperature and partial pressure. The results were interpreted using a simplified model, taking into account both the variation of the effective intracristalline diffusion with the adsorbent loading and the surface resistance, represented by a solid film. The results show that two different types of resistances can be found on the crystals surfaces. The first resistance, called "native resistance" is present as soon as the crystal is synthesised, whereas the other one, called "evolving resistance" is generated during the sample storage or during the adsorption experiments. The evolving resistance can be strongly reduced by washing the crystal surface with fluorhydric acid, which is not the case for the native resistance. It is therefore probable that the evolving resistance is due to a partial blockage of the pores due to an amorphization of the first crystal layers. By studying the influence of the different operating conditions (temperature, fluid phase concentration, adsorption vs. Desorption), we were able to propose a mechanism for the native resistance. Fluid phase molecules are first strongly adsorbed on the surface, as the surface adsorption isotherm is very favourable. The adsorbate then diffuses on the surface until it eventually penetrates into the microporosity
41
SCHAFFHAUSER, VERONIQUE. "Etude de deux systemes autoorganises : polystyrene isotactique/cis-decaline et tetraoctanoate de cuivre(ii)/cyclohexane". Université Louis Pasteur (Strasbourg) (1971-2008), 1994. http://www.theses.fr/1994STR13172.
Testo completoAbstract (sommario):
On s'interesse a l'organisation moleculaire d'un systeme de polymere dont la phase gel est bien connue et d'un systeme de petites molecules, analogues a des surfactants, susceptible de former un gel. Pour le systeme polystyrene isotactique/cis-decaline, on etablit le diagramme de phases temperature-concentration, a partir d'experiences de calorimetrie differentielle a balayage, de diffraction de neutrons et de diffusion de neutrons aux petits angles. On montre l'existence, entre la phase gel (a basse temperature) et la phase cristalline (a haute temperature), de deux phases intermediaires en solvatation et en organisation: en allant du gel a l'etat cristallin anhydre la solvatation diminue, alors que l'organisation augmente. La conformation de la chaine de polystyrene est vermiforme pour le gel et repliee pour les autres phases. Le systeme de petites molecules tetraoctanoate de cuivre(ii)/cyclohexane est caracterise par rheologie. Bien qu'il ait une viscosite considerable, il ne peut etre decrit qu'en terme de pseudogel. Des experiences de diffusion de neutrons aux petits angles montrent l'existence de batonnets. Sous contrainte sinusoidale, on trouve une dynamique des chaines qui met en jeu des reactions de scission-recombinaison. Mais celle-ci ne correspond pas aux modeles existants. Le systeme est caracterise comme une nouvelle espece de polymere vivant
42
Abbasi, Mehdi [Verfasser], e Uwe [Akademischer Betreuer] Riedel. "Kinetic modelling of cyclohexane oxidation with the PAH precursor formation / Mehdi Abbasi ; Betreuer: Uwe Riedel". Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2019. http://d-nb.info/1204061203/34.
Testo completo
43
Grau, Fanny. "Nouvelle cycloisomérisation de diènes-1,6 catalysée par le triflimidure d'étain (IV) : applications à la synthèse de molécules odorantes". Nice, 2007. http://www.theses.fr/2007NICE4008.
Testo completoAbstract (sommario):
Les gem-diméthyles cyclohexanes substitués constituent des cibles de molécules odorantes. Le développement de méthodes de synthèse efficaces permettant l’accès à de nouvelles molécules dérivées de ces structures représente de ce fait un des challenges de la chimie des parfums. Dans ce contexte, la mise au point d’un système catalytique permettant la cycloisoémérisation de diènes-1,6 multi substitués de structures carbocycliques à six chaînons a constitué l’objectif de ce travail de thèse. L’utilisation de superacides de Lewis de type triflates et triflimidures métalliques a permis l mise au point d’un système catalytique faisant intervenir en particulier le triflimidure d’étain à 5% molaire dans le nitrométhane. La cyclisation, réalisée dans le liquide ionique a permis le recyclage du catalyseur. L’utilisation de ce système catalytique a été généralisée à la cycloisoémérisation de divers diènes-1,6 en cyclohexanes correspondants et permet aussi l’accès à des structures carbocycliques à sept chaînons et à des δ- et γ-lactones. La méthode a ensuite été appliquée à la synthèse de diverses structures de départ pour permettre l’obtention, par dérivation de nouvelles molécules d’intérêt potentiel pour la parfumerie. Une étude mécanistique faisant appel à des analyses par RMN a permis de proposer une chélation entre le triflimidure d’étain et le diène-1,6 conduisant, après passage par un intermédiaire carbocationique à la cyclisation. Enfin, l’incorporation partielle de deutérium a permis de proposer une dernière étape de protoanalyse extra moléculaire.
44
Tremblay, Luc. "Études par micro-imagerie RMN de la démixtion en milieu poreux du mélange binaire aniline-cyclohexane". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq26402.pdf.
Testo completo
45
Cone, Margaret Elizabeth. "Effects of Solvent Composition and Hydrogen Pressure on the Catalytic Conversion of 1,2,4,5-Tetrachlorobenzene to Cyclohexane". Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4655.
Testo completoAbstract (sommario):
Halogenated hydrophobic organic compounds (HHOCs) such as 1,2,4,5-tetrachlorobenzene (TeCB) present a threat to both human health and the environment. The common occurrence and recalcitrant nature of HHOCs as soil contaminants necessitate an effective soil remediation method. Wee and Cunningham (2008, 2011, 2013) proposed a clean-up technology called Remedial Extraction and Catalytic Hydrodehalogenation (REACH), which pairs solvent extraction of HHOC contaminants from soil with catalytic hydrodehalogenation to destroy contaminants. Wee and Cunningham (2008, 2011, 2013) utilized a palladium (Pd) catalyst to hydrodehalogenate TeCB to benzene. However, benzene is still a toxic contaminant. Prior research has demonstrated that Pd-catalyzed hydrodehalogenation (HDH) can be paired with Rh-catalyzed hydrogenation to transform TeCB to cyclohexane, which is a less toxic end product (Osborn 2011; Ticknor 2012). However, there remains a need to quantify the effects of different operating conditions on the catalytic reaction rates upon which the technology relies.
It was hypothesized that (1) an increased ratio of water to ethanol in water/ethanol solvents would increase the reaction rates of both Pd-catalyzed HDH and Rh-catalyzed hydrogenation, and (2) catalytic reaction rates would be constant above a hydrogen pressure threshold, but would decrease with decreasing hydrogen pressure beneath the threshold. Thus, the objective of this thesis was to contribute to the development of optimal operating parameters for the REACH technology by quantifying the effects of solvent composition and hydrogen pressure on the catalytic conversion of TeCB to cyclohexane in water/ethanol solvents in a batch reactor.
Complete conversion of TeCB to cyclohexane was achieved at all experimental conditions tested. The data were consistent with an apparent first-order kinetics model where Pd-catalyzed HDH and Rh-catalyzed hydrogenation occur in series. The effects of three water/ethanol solvent compositions (33:67, 50:50, 67:33) were investigated at 50 psi hydrogen pressure. HDH rate coefficients increased monotonically with an increasing fraction of water in the solvent. When the water fraction in the solvent was increased from 50% to 67%, a larger HDH rate coefficient increase was observed than when the water fraction was increased from 33% to 50%. In both cases, the observed increases were statistically significant at a 95% confidence level. For hydrogenation, rate coefficients at 33% and 50% water were approximately equal. The hydrogenation rate coefficient at 67% water was much greater than the rate coefficients at 50% and 33% water, but the increase was not statistically significant at a 95% confidence level. The observed time for complete conversion of TeCB to cyclohexane decreased with an increasing fraction of water in the solvent, from 12-18 hours with a 33% water solvent to 8-12 hours with a 50% water solvent, and to 1-1.5 hours with a 67% water solvent.
The effects of three hydrogen pressures (50 psi, 30 psi, 10 psi) were investigated with a 50:50 water/ethanol solvent. HDH rate coefficients increased monotonically with decreasing hydrogen pressure, though the trend was not statistically significant at a 95% confidence level until the pressure was decreased from 30 psi to 10 psi. This trend can be attributed to the displacement of TeCB by hydrogen on the catalyst surface at higher hydrogen pressures. For hydrogenation, the data suggest that rate coefficients are independent of hydrogen pressure in the pressure range of 10-50 psi, since no statistically significant hydrogen pressure effect was observed. Complete conversion of TeCB to cyclohexane was achieved at hydrogen pressures as low as 5 psi.
These findings suggest that a greater fraction of water in the solvent should be utilized in the REACH system when feasible to maximize catalytic reaction rates. These findings also suggest that the REACH system could be operated at hydrogen pressures as low as 5 psi, which would further improve the safety of the technology.
46
Child, Simon. "Synthesis, electrochemical and electrocatalytic properties of transition metal complexes based on cyclohexane-supported bis-imino pyridines". Thesis, University of East Anglia, 2017. https://ueaeprints.uea.ac.uk/66634/.
Testo completoAbstract (sommario):
This thesis concerns the design and synthesis of transition metal complexes based on cyclohexane-supported bis-imino pyridines for use as electrocatalysts for hydrogen evolution, towards the aim of renewable energy storage. To investigate the effect of secondary coordination interactions on electrochemistry and electrocatalytic response to protons, a series of transition metal complexes with the same fundamental bis-imino pyridine chelating groups, but with different ligand backbones of cyclohexane and cyclohexanol were synthesised. Two isomers of the cyclohexanol ligands were synthesised giving the hydroxyl groups positioned either distal or proximal to the metal centre, due to the conformational lock that occurs on metal coordination. Coordination of these ligands to metal salts of Zn, Mn, Co, Ni and Cu gives a range of geometries. Ligands with no hydroxyl group (10, L1) or a distal (trans) hydroxyl (5, L2) both give octahedral geometries, whereas a proximal (cis) alcohol (9, L3) gives trigonal prismatic geometry for Zn, Mn and Co, but square-pyramidal geometry for Cu. All of the complexes synthesised were shown to give rich electrochemistry, largely due to the redox non-innocent bis-imino pyridine ligands. The presence or absence and position of the hydroxyl group are shown to have a large effect on the cyclic voltammetry. This includes evidence for molecular motion involving the interconversion between different geometries: specifically trigonal prismatic and octahedral or square-based pyramidal. Electrocatalysis is focused on the series of cobalt complexes as these were shown to give the largest response to acetic acid. Catalytic parameters, η, and TOFmax, of the cobalt complexes follow a trend in increasing η and TOFmax from the propane backbone, to cyclohexane backbone, to the distal cyclohexanol, to the proximal cyclohexanol. However bulk electrolysis of CoL3N with acetic acid indicates that proton reduction to hydrogen is not the primary electrocatalytic process for this complex, and suggests reduction of solvent. Future studies must address the nature of this process, and unambiguously establish those of the other complexes.
47
Idrissa, Almoustapha. "Etude d'agrégats de molécules de benzène en matrice de cyclohexane solide par spectroscopie infrarouge de Fourier". Poitiers, 1995. http://www.theses.fr/1995POIT2305.
Testo completoAbstract (sommario):
L'objet de cette these est l'etude d'agregats de molecules de benzene formes en matrice de cyclohexane solide, par spectrometrie infrarouge. Dans les agregats moleculaires, a basse temperature, il y a decomposition des modes de vibrations internes de la molecule en plusieurs sous-niveaux, sous l'effet de l'interaction intermoleculaire, par un mecanisme de transfert resonnant de l'energie vibrationnelle (exciton de davydov). Notre etude consiste a observer l'evolution de la structure des bandes d'absorption infrarouge des agregats, lorsqu'ils evoluent de la molecule isolee vers le cristal de benzene. Nous avons suivi la variation du profil des bandes d'absorption de classe de symetrie a#2#u, e#1#u, b#1#u, et e#1#u situees respectivement a 672,6, 1482, 3057 et 3068 cm#-#1 au niveau de la molecule libre de benzene, en fonction de la concentration de benzene dans la matrice. Les resultats obtenus sont interpretes dans le concept de la theorie de l'exciton vibrationnel et de la theorie des groupes. Pour des concentrations de benzene tres faibles (0,2 a 0,5%), les spectres obtenus sont caracteristiques de molecules de benzene isolees en matrice. Pour les concentrations voisines de 1 et 2%, des molecules isolees, des dimeres et des agregats de faibles dimensions ont ete observes dans la matrice. A partir de 3%, nous avons obtenu des microcristaux (agregats ordonnes) de structure identique a celle du cristal de benzene. Ces resultats ont montre que la structure des agregats evoluent tres rapidement avec la concentration de benzene. L'ecart des niveaux d'energie du monomere et du dimere, a permis de determiner le parametre d'interaction resonnante le plus fort, de l'ordre de 2,63 cm#-#1. Le cyclohexane presente une transition de phase ordre-desordre a t#c = 186 k. Nous avons montre que cette transition de phase peut etre caracterisee par une etude en fonction de la temperature, de la structure excitonique des agregats ou du deplacement en frequence et de la largeur a mi-hauteur de la bande d'absorption de la molecule de benzene piegee en matrice
48
Ducourty, Bruno. "Activation et utilisation de catalyseurs Pt/Al2O3-Cl en hydroisomérisation du n-hexane et du cyclohexane". Caen, 2001. http://www.theses.fr/2001CAEN2005.
Testo completoAbstract (sommario):
Les alumines chlorées sont les catalyseurs les plus actifs pour l'hydroisomérisation des n-alcanes : elles sont utilisables dès 100-120°C, contre 150°C pour les zircones sulfatés et 250°C pour les zéolithes. Elles sont cependant moins étudiées vu leur extrême sensibilité aux poisons (H2O). Les alumines chlorés sont habituellement préparées à des températures qui peuvent atteindre 650°C. Nous avons utilisé une nouvelle méthode, l'imprégnation de l'alumine par le DCEA (dichloroéthylaluminium) à 50°C. Pour tester les propriétés catalytiques des solides otenus, on a choisi l'isomérisation d'unmélange n-hexane/cyclohexane à 150°C. Le solide imprégné possède déjà une activité catalytique non négligeale mais celle-ci baisse rapidement avec le temps de travail. Nous avons amélioré ses performances en prétraitant le solide par l'hydrogène. Soumis au flux de réactifs, le catalyseur prétraité commence par s'activer, puis subit une désactivation lente. Nous avons établi que le prétraitement par H2 à 400°C procurait à la fois l'activation la plus rapide et le meilleur niveau de conversion. L'activité dépend en outre du taux de chlore fixé lors de l'imprégnation. L'addition de CCl4 à la charge réactionnelle augmente aussi l'activité, tout en réduisant la période d'induction. On atteint des performances comparables é celles des alumines chlorées activées par HCl à 650°C. La quantité de HCl présent à la surface des catalyseurs imprégnés et prétraités a été mesurée par désorption en température programmée (T. P. D. ). L'acidité a aussi été caractérisée par spectroscopie IR-TF et par microcalorimétrie d'adsorption.
49
Driega, Alex B. (Alexander Brooke) Carleton University Dissertation Chemistry. "An analysis of factors contributing to isotropic [superscript] 13C shifts in 1,2- Dialkoxybenzene and Cyclohexane derivatives". Ottawa, 1992.
Cerca il testo completo
50
Tremblay, Luc. "Études par micro-imagerie RMN de la démixtion en milieu poreux du mélange binaire aniline-cyclohexane". Sherbrooke : Université de Sherbrooke, 1997.
Cerca il testo completo