Дисертації з теми "Azo compounds"
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1
Iannarelli, Paul M. "Routes to novel azo compounds." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/3492.
Анотація:
Routes to novel heterocyclic azo compounds and components of use as potential inkjet dyes were investigated. A new route to fluorenones from biphenyl acid chlorides using FVP (Flash Vacuum Pyrolysis) has been discovered. Fluorenone and 4-methylfluoren-9-one were prepared by FVP of 2-phenylbenzoyl chloride and 2-methylbiphenyl-2-carbonyl chloride respectively. Xanthen-9-one and thioxanthen-9-one were also prepared by FVP from the corresponding acid chlorides. 9-Phenanthrol could also be prepared via the FVP of biphenylacetyl choride and the application of this method to a heterocylic thiophene system afforded naphtho[1,2-b]thiophen-4-ol. Naphtho[2,1-b]thiophen-4-ol and naphtho[1,2-b]furan- 4-ol could be obtained in low yields by the FVP of (2-thiophen-3-ylphenyl)acetic acid methyl ester and (2-furan-2-ylphenyl) acetic acid methyl ester over a tungsten trioxide catalyst. Coupling of these systems with the diazonium salt of Acid Yellow 9 afforded the corresponding azo compounds. New heterocyclic dyes were also prepared from the condensation of heterocyclic hydrazines with 4,9-disulfophenanthrenequinone. Pyridine, pyridazine, phthalazine, isoquinoline and 2-quinoline disulfophenanthrene quinone metallised 2:1 nickel complexed magenta dyes were prepared. Industrial tests by standard methods revealed the pyridazine dye has a particularly impressive balance of light and ozone fastness over similar magenta dyes. The reaction of an arylnitro compound with 2-aminopyridine appeared to be an attractive and high yielding route to 2-(phenylazo)pyridine. However, application of this reaction to substituted and naphthalene systems failed. This afforded byproducts due to nucleophilic substitution of groups such as methoxy and the relatively uncommon nucleophilic substitution of hydrogen with none of the required azo products obtained. Therefore it appeared that the reaction of a nitro and amine was not a robust and versatile route to heterocyclic azo compounds. An alternate route to heterocyclic azo compounds involved the use of the Mills reaction by the condensation o-anisidine, p-chloroaniline, 2-aminophenol, 3- aminophenol, naphthylamine, 8-amnioquinoline and 2-acetylamino-5-aminobenzenesulfonic acid with 2-nitrosopyridine afforded the heterocyclic azo products in moderate to high yields. The Mills reaction does appear to be the favored route to heterocyclic azo compounds. Several factors were identified which affect the process of bisazo coupling of chromotropic acid and products obtained. Reaction at the ipso position of monoPACAs (2-phenylazochromotropic acid) leading to increased yields of the ipso substitution monoPACA by-product as opposed to the expected bisazo coupling position was a major problem. Studies indicated reactivity at the ipso position was greatly reduced by the presence of electron withdrawing groups around the phenyl ring of the monoPACA. Further study indicated reaction at the bisazo coupling position increased with the strength of the diazonium salt used in bisazo coupling. Therefore the electronic nature of the monoPACA starting material and the diazonium salt used in bisazo coupling greatly affected the products obtained. Reaction pH studies also revealed attack at the bisazo coupling position increases with pH and at lower pH (5.0 – 8.0) attack at the ipso position dominated. Reactivity of the monoPACA starting material also increased with pH. The influence of steric effects upon bisazo coupling revealed, in the cases where ortho sulfonic acid groups were present in the monoPACA, a reduction in attack at the ipso position. Hence the reaction appeared to be directed towards the required bisazo coupling position.
2
Newington, Ian M. "Azo-anions in organic synthesis." Thesis, University of Oxford, 1985. http://ora.ox.ac.uk/objects/uuid:690ab891-be13-4582-a029-47974d20adac.
Анотація:
Novel synthetic applications of ambident azo-anions derived from hindered hydrazones have been investigated. Reaction with electrophiles occurred predominantly at carbon as the N-addition pathway was sterically retarded. Trityl, diphenyl-4-pyridylmethyl (DPP) benzhydryl, and t-butyldiphenylmethyl (BDP) hydrazones of various aldehydes and ketones were prepared in good yields from the corresponding hydrazines and carbonyls in aqueous methanol. The lithium salts derived from trityl and DPP hydrazones, by treatment with methyl lithium at -55°C, reacted with aldehydes and ketones to generate azo-alkoxides. These could be diverted to alcohols,by sequential protonation and spontaneous homolysis (about -20°C) in the presence of ethanethiol, or to alkenes,by treatment with phosphorus trichloride at -78 G followed by azo-homolysis. The reactions enabled efficient reductive cross-coupling of aldehydes and ketones. The mechanism of the alkene forming reaction was investigated. Anions of benzhydryl hydrazones were found to react inefficiently by a G-addition pathway giving mainly N-addition products. Anions of BDP hydrazones conveniently gave excellent yields of azo-alkanes upon treatment with alkyl halides,but no products were obtained on reaction with carbonyl electrophiles. The azo-alkanes could be isolated and purified and acted as key intermediates for several synthetically useful transformations. Homolysis in refluxing benzene with thiophenol gave alkanes in good yields. Phenylselenenyl-, bromo-, and chloro-alkanes,and β-alkylstyrenes were generated when thiol was replaced by diphenyl diselenide, N-bromosuccinimide, N-chlorosuccinimide and β-nitrostyrene respectively. Treatment of the azo-alkanes with trifluoroacetic acid generated benzophenone alkylhydrazones. These were dissolved in ethanol with concentrated hydrochloric acid, thereafter hydrolysis yielded alkylhydrazines or treatment with hydrogen (1 atm., 50°C, 20h) over 10% Pd/C generated primary amines by a novel use of carbonyls as α-aminocarbanion equivalents.
3
MacDonald, Ranald John. "Novel routes to heterocyclic Azo compounds." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5787.
Анотація:
The potential use of electron-deficient heterocyclic azo compounds as inkjet dyes was explored. 2-Nitrosopyridine could be used to form a series of azo compounds via the Mills’ reaction with electron-rich aromatic amines. Conditions for this process were optimised by varying solvent and pH. In the presence of ethers, 2-nitrosopyridine is quickly reduced to azoxypyridine. This reaction follows first order kinetics; diethyl and diisopropyl ether react at similar rates, whereas cyclic ethers such as THF are far slower. Organic bases such as Hunigs base were also found to promote formation of azoxypyridine. The mechanism of this reduction was studied. The electrochemistry of 2-nitrosopyridine and azoxypyridine was also explored. Using the optimised conditions for the Mills’ reaction, 2-nitrosopyridine not only reacts with electron-rich amines but also electron-deficient examples. The series was also expanded to include other heterocycles as well as pyridine via the corresponding heterocyclic nitroso compound. Other nitroso compounds prepared were 1- nitrosoisoquinoline, 2-nitrosopyrazine, 4-nitrosopyrimidine and 2-nitrosopyrimidine. The absorption maxima of azo compounds prepared from these precursors were found to correlate with the values for the corresponding azobenzenes. 2-Nitrosopyridine and 2-nitrosopyrimidine react with diamines to give monoazo products. These in turn could be diazotised and coupled with various components to give either bisazo or trisazo compounds. These dyes were tested for their ozone and light fastness properties. The bisazo examples were found to have good ozone fastness but poor light fastness. The pyrimidine examples only showed a slight improvement in ozone and light fastness compared to their pyridine analogue. 2,3-Phthalocyanines are important components in cyan dyes. New routes to precursors of these compounds were explored using flash vacuum pyrolysis (FVP).
4
江鳳思 and Fung-sze Kong. "The chemistry of Osmium carbonyl clusters containing organomercurials and azo-compounds." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31238695.
5
Kong, Fung-sze. "The chemistry of Osmium carbonyl clusters containing organomercurials and azo-compounds /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21021545.
6
Clarke, Ronald James. "Kinetic and equilibrium studies of cyclodextrin-azo dye inclusion complexes /." Title page, contents and abstract only, 1985. http://web4.library.adelaide.edu.au/theses/09PH/09phc5992.pdf.
Анотація:
Thesis (Ph. D.)--University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1985.Offprints of two author's journal articles inserted at end of the v. Includes bibliographical references (leaves 10-12).
7
McNair, Craig. "Synthetic approaches to substituted Ca4B-type azo compounds." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366902.
8
Shahkar, G. R. "Thermal decomposition of azo compounds in the gas phase." Thesis, Swansea University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638804.
9
West, Lee Charles. "A study of bibracchial lariat ether complexes and linked cyclodextrin dimer complexes." Title page, contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09PH/09phw5182.pdf.
Анотація:
Includes errata attached to first leaf. Includes bibliographical references. The complexation of a range of monovalent and divalent metal ions by the bibracchial lariat ethers has been investigated. Also investigates the complexation of metal ions and the anionic azo dye Brilliant Yellow by the diazacrown linked cyclodextrin dimers.
10
Hywel, Meilir. "Laser control of the photoisomerisation of azo-compounds : a theoretical study." Thesis, Bangor University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520068.
11
Haria, Mehul. "Design, synthesis, and optical characterization of a novel, biocompatible azo-polymer." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101850.
Анотація:
The goal of this thesis was to create a novel stable water-soluble azo polymer with photoswitchable properties, which was to be used as a scaffold in directing neuron growth. The new polymer, PDR2, was synthesized and extensively characterized to understand its physical and chemical properties, as well as to ascertain the structure. Characterization techniques included nuclear magnetic resonance, thermogravimetric analysis, differential scanning calorimetry, absorption spectroscopy, and ellipsometry. The photoresponsive properties of the polymer were then studied by examining quantum yields and birefringence, and the variation of these properties with humidity was examined, after being deposited onto thin films using layer-by-layer self-assembly. Quantum yields were found to increase with humidity up to a maximum determined to be at approximately 30% relative humidity, and were then found to decrease with increasing humidity. This was thought to be due to a combination of factors including plasticization and the formation of water clusters. Birefringence experiments revealed that the thin films did not produce a stable birefringence state. Many factors, including low azo content in the polymer, interaction with polymer side groups, and the mobility of polyelectrolyte multilayers were thought to contribute to these results.
12
Ye, Jianchang. "Roles of graphite in the reduction of azo-aromatic compounds with elemental iron." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 137 p, 2006. http://proquest.umi.com/pqdweb?did=1172118261&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.
13
Akwi, Faith Mary. "Scalable chemistry involving diazonium salts." Thesis, Nelson Mandela Metropolitan University, 2016. http://hdl.handle.net/10948/6909.
Анотація:
Herein an alternative approach aimed at reducing the cost of numbering up technique as a scale up strategy for chemical processes from the laboratory bench top to the industry is explored. The effect of increasing channel size on the reaction conversion of the synthesis of azo compounds is investigated. This was achieved via a systematic investigative understanding of the synthesis in microreactors where a proof of concept study was performed to determine the optimum reaction parameters in azo coupling reactions involving couplers with aminated or hydroxylated groups in Little Things Factory-MS microreactors (Channel diameter: 1.0 mm) It was found that at slightly alkaline conditions (pH 8.55) and at a temperature of 25 °C, excellent conversions were attained in the azo coupling reaction of the diazonium salt solution of 2,4-dimethylaniline to 2-naphthol. On the other hand, the azo coupling reaction of the diazonium salt solution of p-nitroaniline to diphenylamine was found to thrive at a pH of 5.71 and at a temperature of 25 °C. Using, these optimized reaction parameters, the in-situ and reactive quench of diazonium salts in LTF-MS microreactors was investigated where it was found that at a flow rate of 0.2 ml/min, 0.03 ml/min and 0.07 ml/min of diazotizable amine & HCl, sodium nitrite and coupler solutions respectively, a conversion of 98% is achieved in approximately 2.4 minutes. A library of azo compounds was thus generated under these reaction conditions from couplers with aminated or hydroxylated aromatic aromatic systems. The scaled up synthesis of these compounds in a homemade PTFE tubing (ID 1.5 mm) reactor system was thereafter investigated and comparable conversions were observed. Capitalizing on the benefits of a large surface area and the short molecular diffusion distances observed in microreactors, in-situ phase transfer catalyzed azo coupling reaction of diphenylamine to p-nitroaniline was also explored. In this investigation a rapid and easy optimization protocol that yielded a 99%, 22% and 33% conversion of diphenylamine, carbazole and triphenylamine respectively in approximately 2.4 minutes using Chemtrix microreactors was established. On increasing the microreactor channel internal diameter in the scaled up synthesis approach, it was found that a 0.5 mm increase in channel internal diameter does result in lower reaction conversions.
14
Kneller, Mark Byron. "Controlling peptide conformations : stabilizing helices /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/8531.
15
Choi, Ming Fai. "Design and synthesis of coordination polymer gels and high dichroic ratio azo dyes /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202002%20CHOI.
16
Simmonds, Michelle. "The reactions of some simple ester-substituted radicals in solution." Thesis, University of York, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387620.
17
Wallace, Trevor Haig. "Biological Treatment of a Synthetic Dye Water and an Industrial Textile Wastewater Containing Azo Dye Compounds." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/34115.
Анотація:
In this research, the ability of anaerobic and aerobic biological sludges to reduce and stabilize azo dye compounds was studied. Synthetic dye solutions and an industrial textile wastewater were both treated using anaerobic and aerobic biomass, separately and in sequential step-treatment processes. The primary objective was to reduce the wastewater color to an intensity that complies with the Virginia Pollutant Discharge Elimination System (VPDES) permit level. This level is set at 300 American Dye Manufactures Institute (ADMI) units. Further objectives were to achieve reductions in the total kjehdal nitrogen (TKN) and total organic carbon (TOC) in the wastewater. Anaerobic and aerobic treatment systems were both effective in reducing the wastewater color; however, anaerobic treatment generally produced the greatest color removal. Anaerobic/aerobic (ANA/AER) sequential step-treatment provided the best reductions in ADMI color, TKN and TOC. Anaerobic/aerobic/anaerobic/aerobic (ANA/AER/ANA/AER) sequential step-treatment did not yield greater reductions in ADMI color, TKN, or TOC as compared to ANA/AER sequential step-treatment.Master of Science
18
Czerniewski, Alexandre Adam. "Development and characterization of novel nitric oxide-releasing probes for magnetic resonance imaging." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112393.
Анотація:
While providing non-invasive tissue detection, magnetic resonance imaging (MRI) presently possesses limited sensitivity for protein target recognition. This limitation was addressed for the target beta-galactosidase (beta-gal) by constructing three beta-gal-specific MRI probes. The probes are based on a bipartite design in which a vasoactive moiety known as a diazeniumdiolate (NONOate) is bound to a specifier, specifically galactose. Upon galactose' interaction with beta-gal, the NONOate is cleaved from galactose, and actively generates nitric oxide (NO). The released NO leads to microvascular permeability changes in surrounding tissues affecting localized T1 measurements. These changes serve as a quantitative index of beta-gal detection. The three beta-gal-specific NO-releasing probes constructed include GALPYRNONO, GALPIPNONO and a 'bi-functional' probe, which is similar to the first two but with glucose additionally incorporated so that the third probe may easily cross cellular membranes. Synthesis and characterization of this novel class of MRI probes are described in this work.Keywords: non-invasive detection, magnetic resonance imaging (MRI), nitric oxide (NO), diazeniumdiolates (NONOates), NO-releasing compounds, novel MRI probes, molecular targets, protein targets, specifier, vasoactive, vasodilation, microvascular permeability, tissue localization, bipartite systems, bifunctional probes, blood-brain barrier, cell membrane trafficking, saccharide-bound NONOates, sugar diazeniumdiolates, glycosylated diazeniumdiolates, galactose, beta-galactosidase, glucose, glucose transporters, thermal & photolytic degradation, half-life optimization, Griess test, rat serum, stability.
19
Ozkan, Yucel Umay G. "Co-treatment Of Hazardous Compounds In Anaerobic Sewage Sludge Digesters." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609952/index.pdf.
Анотація:
Xenobiotic compounds, which are exclusively man made, are produced in large quantities every year and released to the environment. Besides, anaerobic sludge digestion offers advantage in co-treatment of hazardous substances produced by the industry. The performance of the digesters can be monitored by modeling efforts. In this study, Anaerobic Digestion Model No.1 (ADM1) was calibrated, and validated for full-scale digester, lab-scale digester, and lab-scale digester seeded with totally different anaerobic biomass than that of full-scale digester. The model xenobiotic compound, a mono azo dye RO107, was co-treated with sewage sludge in an anaerobic digester. High removal efficiencies as 98% was found for azo dye at standard operating conditions of anaerobic digesters. The digester performance was not effected from azo dye or its reduction products. The dye reduction mechanism was modeled by biochemical mechanism due to unspecific enzymes and by chemical mechanism due to sulfide reduction. Some of the dye metabolites were suggested to be degraded by aerobic biotreatment. The anaerobic reduction metabolites of RO107 were identified as 2-(4-aminophenylsulfonyl) ethanol and 2,5-diamino-4-formamidobenzenesulfonic acid, and sulfanilic acid.
20
Palacios, Sara. "Decolourization of azo and anthraquinone dyes by mean of microorganisms growing on wood chips." Thesis, Växjö University, School of Technology and Design, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-5168.
Анотація:
Reactive Black 5 and Procion Red MX 5B, an azo and anthraquinone dye repectively were decoulorized by mean of microorganisms growing on wood chips. The process consisted of three reactors, two anaerobic reactors and one aerobic reactor. The anaerobic process was used in order to make it possible to break the nitrogen bond of the azo group, (-N=N-) and the aerobic one to increase the possibility for the degradation of possible intermediates. After pumping wastewater through the system it was shown that mixtures or Reactive Black 5 and Procion Red MX 5B were efficiently decolourised at 50 mg/l as well as 200 mg/l of each of the dyes.
21
Neves, Ubaldo Martins das. "Estudo e aplicações do fenômeno de absorção de dois fótons em moléculas azo-aromáticas." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-18022011-083247/.
Анотація:
Neste trabalho estudamos o processo de absorção de dois fótons em compostos azoaromáticos, abordando tanto aspectos fundamentais quanto aplicados. Moléculas azo-aromáticos têm recebido especial atenção nos últimos anos devido as suas potencias aplicações em dispositivos para armazenamento óptico de informação, modulação da luz e geração de relevos em superfície, processes estes associados ao mecanismo de foto isomerização. Os trabalhos apresentados nessa tese tiveram como principal foco explorar o fenômeno de absorção de dois fótons, utilizando a propriedade de foto-isomerização das moléculas azo-aromáticas. Nosso objetivo foi estudar as vantagens que podem ser obtidas pela utilização de pulsos intensos de luz, que interagem de maneira não linear com a matéria, para desenvolver aplicações utilizando compostos azo-aromáticos. Inicialmente, estudamos o processo de absorção de dois fótons em uma nova família de compostos azo-aromáticos, denominados Salen Dyes. Investigamos a influencia da presença de íons metálicos no processo de absorção de dois fótons dessas moléculas. Nossos resultados mostraram que, devido a ausência de conjugação entre as estruturas azo-aromáticas conectadas pelo metal, este tem pouca influência no processo não linear estudado. Pelo uso de um modelo de soma de estado para a seção de choque de absorção de dois fótons, fomos capazes de determinar os momentos de dipolo de transição destas moléculas. Em seguida, implementamos uma técnica para estudar o processo de armazenamento óptico, induzido através da orientação molecular dos compostos azo-aromáticos, via absorção de dois fótons. Observamos que de fato é possível se observar birrefringência induzida por dois fótons nestas moléculas, a qual esta confinada ao volume focal, conforme demonstrado pela obtenção de armazenamento tri-dimensional. Finalmente, exploramos o processo de controle coerente via formatação de pulsos ultra-curtos para manipular o processo de birrefringência induzida por dois fótons em compostos azo-aromáticos. Foi demonstrado que apenas a através da manipulação da fase do pulso ultra-curto, é possível modular a birrefringência induzida em filmes de compostos azo-aromáticos.Here we investigated fundamental and applied aspects of the two-photon absorption process in azoaromatic compounds. Azoaromatic molecules have been studied in the last few years due to their applications in optical storage devices, light modulators and surface relief gratings, processes related to the photo-isomerization mechanism. The main focus of the results presented in this thesis was to explore the two-photon absorption process, taking advantage of the intrinsic photo-isomerization of the azo-aromatic chromophores. Our main goal was to study the advantages of utilizing intense pulses, which promote nonlinear excitation, to develop application with azo-aromatic compounds. Initially, we studied the two-photon absorption process in a new class of azo-aromatic compounds, named Salen Dyes. We investigated the influence of metal ions, presented in the Salen Dyes structure, on the two-photon absorption spectrum. Our results revealed that the metals have practically no influence in the nonlinear optical properties due to the lack of conjugation between the azo-moieties in the Salen Dyes. Through a theoretical model based on a sum-over-states calculation, we were able to determine the transition dipole moment of these molecules. Subsquently, we implememnted a technique to study the two-photon induced birefringence, resulting from the molecular re-orientation, in azo-aromatic compounds. We observed that the two-photon induced birefringence is confined to the focal volume, s demonstrated in a three dimensional optical storage experiment. Finally, we used coherent control processes to manipulate the two-photon induced birefringence in azo-compounds. It was demonstrated that it is possible to modulate the optically induced birefringence by manipulating the phase of the ultra-short pulses, via pulse shaping techniques.
22
Lai, Joshua. "Synthesis and characterization of Prussian red derived microparticles for the heterogeneous photo-fenton oxidation of azo-type textile dyes as pollutants." HKBU Institutional Repository, 2020. https://repository.hkbu.edu.hk/etd_oa/886.
Анотація:
Inorganic colloidal synthesis, without a doubt, lies at the foundation of many contemporary areas of nanoscience and nanotechnology. At the advent of the 21st century, much progress has been made in the size, shape / morphological control and surface engineering of metal oxides resulting in a diverse library of macroscopic crystal architectures with well-defined surface properties. In this thesis, we start by introducing the self-assembly of the iron(oxy-, hydro-)xide while briefly reviewing some fundamental concepts of solid-state chemistry. Specific information on the family of iron oxide and iron(oxy-, hydro-)xide, as relevant to crystalline phase control, has been highlighted to direct our discussion of the synthesis of diverse crystal morphologies. Furthermore, we briefly underline and discuss the kinetic and thermodynamic control of colloidal crystal morphologies through reasonably established knowledge of anisotropic growth rates in the perspective of iron oxides' facets or crystalline planes. Lastly, we review the state-of-the-art wet chemical synthetic approaches, while using different iron(oxy-, hydro-)xide crystals as examples, for the purpose of explaining our synthetic work of choice. The main work of this thesis is entirely focused on the "facile synthesis and fine morphological tuning of branched hematite (??-Fe2O3) crystals for photodegradation of azo-type dyes".. We would discuss the crucial parameters for fine morphological tuning in the context of controlling the anisotropic growth rates of branched ??-Fe2O3 crystals instead of phase transformation. In our work, we have significantly improved the synthesis of dendritic "feather-like" and "starfish-like" for their size reduced variants for use in photocatalysis.
23
Pereira, Fernanda Stuani [UNESP]. "Estudos de biopolímeros a base de quitina e quitosana quimicamente transformados para quelação de metais e para a captura e fixação de dióxido de carbono." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/139534.
Анотація:
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O presente trabalho descreve modificações estruturais feitas na cadeia lateral do polímero quitosana mediante a N-alquilação com diferentes aldeídos aromáticos, a qual originam bases de Schiff como produtos intermediários, seguido de uma redução com cianoborohidreto de sódio (NaBH3CN). Subsequentemente, reações de acoplamento entre o produto sintetizado N-benzil quitosana e diferentes sais de diazônio foram realizadas para produzir uma nova classe de compostos poli-azóicos a partir deste polímero. Diferentes materiais foram sintetizados para investigar a influencia de diferentes substituintes na complexação de metais e futuros estudos de eficiência biológica. Pela técnica de ressonância magnética nuclear de próton em solução, o grau de substituição dos poli-azo-compostos foi de 46 a 66%. Os compostos foram caracterizados por FT-IR e RMN de 13C no estado sólido e RMN de 15N em solução, que confirmaram a síntese dos derivados poliméricos. Também foi realizado um estudo da interação destes materiais sintetizados com os íons metálicos Cu(II) e Zn(II). Para a caracterização dos complexos, utilizou-se as técnicas de titulação complexométrica, FAAS, MEV, EDS, difratometria de raios X, EPR e TG/DTG. Por titulação complexométrica e FAAS, a quitosana pura mostrou maior capacidade em complexar/adsorver os metais do que seus derivados. A capacidade de adsorver íons Cu(II) foi maior do que íons Zn(II) para todos os compostos. Por MEV e EDS, observou-se que além do cobre coordenado pelos sítios reativos dos materiais, o sal sulfato de cobre foi adsorvido pela superfície polimérica dos mesmos. Assim, foram realizadas reações de complexação utilizando o sal CuCl2.2H2O e os resultados mostraram que esse comportamento não ocorre para este sal. Para os complexos utilizando o sal sulfato de zinco, praticamente não se observa o sal adsorvido na superfície polimérica, devido à baixa capacidade de complexação por esse metal. A difratometria de raios X mostrou uma redução da cristalinidade dos complexos de cobre e zinco formados pela quitosana e o derivado Q1Benzil devido a maior capacidade desses materiais em quelar íons metálicos. Para os complexos de Cu(II) e Zn(II) formados a partir do composto Azo-Anisidina, o índice de cristalinidade aumenta, o que pode estar associado a formação de diferentes ligações de coordenação nesse composto. A formação dos complexos também foi confirmada por espectroscopia Raman. Os espectros de EPR dos complexos de Cu(II) formados a partir do sal CuCl2.2H2O mostram a presença de uma estrutura hiperfina bem resolvida, da mesma forma que foi observado para o complexo Quitosana-CuSO4, na qual a grande maioria dos centros de cobre são monoméricos e provavelmente ligados aos polímeros. As curvas de TG/DTG mostraram que os derivados poliméricos degradam a temperaturas menores que o polímero não modificado, e os complexos com sulfato de cobre apresentaram perfis TG/DTG diferentes dos complexos sintetizados a partir do sal cloreto de cobre. Por fim, tanto a quitosana quanto seus derivados Q1Benzil, Q2Benzil e Q2Benzil utilizando a quitosana de baixo peso molecular se mostraram efetivos na síntese de carbonatos através da captura e fixação de CO2 por estes materiais poliméricos.
The present work describes structural modifications in the side chain of the polymer chitosan by N-alkylation with different aromatic aldehydes, which originates Schiff base as an intermediate, followed by reduction with sodium cyanoborohydride (NaBH3CN). Subsequently, coupling reactions between the synthesized product N-benzyl chitosan and various diazonium salts were carried out to produce a new class of poly-azo compounds from this polymer. Different materials were synthesized to investigate the influence of different substituents on metal chelation and future studies of their biological efficience. From nuclear magnetic resonance technique, the degree of substitution of the poly-azo compounds was between 46 and 66%. The compounds were characterized by FT-IR, 13C NMR in solid state and 15N NMR in solution, which confirmed the synthesis of the polymeric derivatives. The interaction of the synthesized materials with the metal ions Cu(II) and Zn(II) was also studied. For the characterization of such metal complexes, the techniques complexometric titration, FAAS, SEM, EDS, X-ray diffraction, EPR and TG/DTG were employed in this work. By complexometric titration and FAAS, pure chitosan showed greater capacity for complex/adsorb metals than its derivatives. The capacity of adsorbing Cu(II) ions was greater than Zn(II) ions for all compounds. The synthesized complexes were studied by various spectroscopic techniques. By SEM and EDS, it was observed that in addition of copper coordination, copper sulphate salt was adsorbed by the polymer surface. Thus, complexation reactions were carried out using the salt CuCl2.2H2O and the results showed that this behavior does not occur for this salt. For complexes using zinc sulfate salt, hardly observes this salt adsorbed on the polymeric surface due to the low capacity for complexing this metal. The X-ray diffraction showed a reduction of the crystallinity of copper and zinc complexes formed by chitosan and Q1Benzil derivative due to the greater ability of these materials to chelate metal ions. For the complexes of Cu(II) and Zn(II) formed from Azo-Anisidine compound, the crystallinity index increases, which can be associated with formation of different coordination bonds with the compound. The formation of the complex was also confirmed by Raman spectroscopy. EPR spectra of Cu(II) formed from the CuCl2.2H2O salt showed the presence of well resolved hyperfine structure in the same way as it was observed for chitosan-CuSO4, in which the majority of copper centers are monomeric and probably bound to the polymer. The TG/DTG curves showed that polymeric derivatives are less stable than the unmodified polymer, and complexes with copper sulfate had TG/DTG curves different from the complexes synthesized from copper chloride salt. Finally, chitosan and the derivatives Q1Benzil , Q2Benzil and Q2Benzil from low molecular weight chitosan were effective in the synthesis of carbonates through the capture and sequestration of CO2 by these polymeric materials.
FAPESP: 2012/13901-3
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Brown, Erin. "Modulation of intracellular GSH in THP-1 cells during oxidative stress induced by AAPH." Thesis, University of Canterbury. School of Biological Sciences, 2006. http://hdl.handle.net/10092/2629.
Анотація:
The human monocyte-derived THP-1 cell line was incubated with 10mM AAPH in Earle’s Balanced Salt Solution at 37°C for up to 24 hours. Protein hydroperoxide formation occurred after an 8 hour lag phase which corresponded to glutathione loss observed in the cells. SDS-Page analysis confirmed protein degradation occurred after 6 hours. Cell viability measured by the MTT reduction assay also dropped after 8 hours. Reduction of intracellular glutathione levels using BSO caused reduction of the lag phase seen in protein hydroperoxide formation. Cell viability of BSO-treated cells was lower than control cells, indicating the initiation of apoptotic events. Flow cytometry analysis showed no difference between BSO-treated and control cells, indicating that GSH levels do not have an effect on the type of cell death observed in AAPH-induced oxidative damage on THP-1 cells. These results confirmed previous data in the lab suggesting THP-1 cells undergo AAPH-induced necrosis as a result of cellular damage, including the loss of GSH and the formation of protein hydroperoxides.
25
Mohamed, Elham Farouk. "Removal of organic compounds from water by adsorption and photocatalytic oxidation." Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0036/document.
Анотація:
Les effluents industriels sont constitués de molécules de natures très diverses, plus ou moins réfractaires aux classiques traitements biologiques. Les normes de rejets évoluant régulièrement vers des contraintes de plus en plus sévères, il semble aujourd'hui nécessaire de proposer des solutions complémentaires pour atteindre de hauts rendements d'épuration. Le premier procédé mis en oeuvre dans ce travail est l'adsorption sur charbon actif. Le caractère novateur de cette technique se situe dans l'utilisation de charbons actifs fabriqués à partir de boues de stations d'épuration d'eaux usées. La seconde méthode est un procédé hybride innovant combinant adsorption et photocatalyse avec TiO2. Les eaux industrielles ciblées sont les effluents colorés, représentés par la tartrazine, et les effluents phénolés représentés par le phénol, l'acide p-hydroxybenzoïque, le p-chlorophénol er le p-nitrophénol. Pour traiter par adsorption les eaux chargées en phénols, plusieurs charbons actifs commerciaux et six charbons de boues ont été utilisés. Il ressort de cette première étude que, malgré leurs faibles surfaces spécifiques, certains charbons de boues présentent des performances très satisfaisantes. Le procédé séquentiel combinant adsorption et photocatalyse a été réalisé avec plusieurs matériaux: un tissu Ahlstrom contenant du charbon et du TiO2, un charbon actif avec dépôt de TiO2 par MOCVD puis un mélange de charbon actif et TiO2 en poudre. Des résultats prometteurs ont été obtenus pour dégrader la tartrazine, en particulier avec le TiO2 déposé sur charbon actif montrant que la proximité de sites d'adsorption et photocatalytique améliore les performances de l'oxydationIn order to explore a new sequential process for water treatment its two steps, adsorption on activated carbon and in situ photocatalytic oxidative regeneration, were investigated successively. Several commercial activated carbons (AC) and sewage sludge based activated carbons (SBAC) were tested with several phenols and one dye as pollutants. Despite low BET surface SBAC exhibits convenient adsorption properties. Photocatalysis on TiO2 was carried out with several materials to achieve activated carbon adsorption- egeneration process: a multilayer tissue with fixed granular AC and TiO2 on a sheet, a composite with TiO2, CVD deposited on AC, and AC-TiO2 powder mixture for comparison. Promising results were obtained especially with TiO2 deposited on AC proving the vicinity of adsorption and photocatalytic sites to be beneficial
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ALCANTARA, RAQUEL R. "Síntese, caracterização, de nanomaterial zeolítico de cinzas de carvão organomodificado e aplicação como adsorvente na remediação de água contaminada por Rodamina B e Azul Direto 71." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/27960.
Анотація:
Submitted by Marco Antonio Oliveira da Silva (maosilva@ipen.br) on 2017-10-27T12:15:25Z
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A síntese de zeólitas a partir de cinzas leves e pesadas de carvão mineral foi realizada por tratamento hidrotérmico alcalino, as quais foram nomeadas ZCL e ZCP, respectivamente. As zeólitas organomodificadas ZML e ZMP foram obtidas a partir da modificação superficial de ZCL e ZCP, respectivamente, utilizando o surfactante catiônico brometo de hexadeciltrimetilamônio. A partir das soluções remanescentes geradas na síntese de ZCL e ZCP foi possível sintetizar duas novas zeólitas. As características físicoquímicas dos nanomateriais zeolíticos sintetizados, bem como de suas respectivas matérias primas, tais como: capacidade de troca catiônica, massa específica, área específica, composição química, mineralógica e morfológica, entre outras, foram determinadas. Os adsorventes ZML e ZMP foram utilizados na remoção dos corantes Azul Direto 71 (DB71) e Rodamina B (RB) de soluções aquosas em sistema de batelada. Desta forma, quatro sistemas DB71/ZML, RB/ZML, DB71/ZMP e RB/ZMP foram investigados. Os modelos de pseudoprimeira ordem e pseudo-segunda ordem foram aplicados aos dados experimentais para o estudo da cinética de adsorção. O modelo de pseudosegunda ordem foi o que melhor descreveu o processo de adsorção de todos os sistemas corante/zeólita organomodificada. O equilíbrio da adsorção foi analisado a partir de quatro modelos de isoterma, sendo eles: Langmuir, Freundlich, Temkin e Dubinin-Radushkevich (D-R). Os resultados mostram que os modelos de Freundlich e Langmuir melhor descreveram os dados experimentais dos sistemas DB71/ZML e DB71/ZMP, respectivamente. Para os sistemas com RB, o modelo de D-R foi o que melhor se ajustou para ambos adsorventes ZML e ZMP. O planejamento fatorial 24 foi aplicado para a análise dos seguintes fatores que influenciam o processo de adsorção: concentração inicial do corante (Co), pH, dose de adsorvente (M) e temperatura (T). De acordo com as condições estudadas concluiu-se, com o intervalo de confiança igual a 95%, que para o sistema DB71/ZML, os fatores e suas interações que mais influenciam foram C0, M, pH, pH*M, pH*C0, M*C0, pH*M*C0, nessa ordem. No sistema DB71/ZMP, a ordem de influência foi: M, C0, pH, pH*M, pH*C0, M*C0, pH*M*C0. Para os sistemas RB/ZML e RB/ZMP, os resultados foram: M, C0, M*C0, pH, pH*M e M, C0, M*C0, respectivamente. O equilíbrio de adsorção foi atingido em cerca de 40 min para todas as amostras. As porcentagens de remoção do DB71 estavam na faixa de 50 80% e 20 50% para ZML e ZMP, respectivamente. A faixa de porcentagens de remoção do RB variou entre 60 80% e 30 50% para ZML e ZMP, respectivamente.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Carmazen, Paula Carpes Victorio. "Investigação de lesões em DNA induzidas por produtos de redução do corante C. I. Disperse Blue 291." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/9/9141/tde-25102007-151610/.
Анотація:
CI Disperse Blue 291 (CI DB 291) é um corante dinitrobromoaminoazobenzeno com atividade mutagênica para S. typhimurium, aumentada na presença de nitrorredutase, o-acetiltransferase e enzimas microssomais (S9). Neste estudo foram isolados e caracterizados quatro produtos da redução de DB 291 com ditionito de sódio (in vitro), sendo denominados 2- fenilbenzotriazóis não clorados (não-ClPBTAs). Os espectros de absorbância não apresentam o pico correspondente à ligação azo (?λ=613 nm), indicando a redução dessa ligação. Espectros de massas e 1H RMN mostram que os produtos são dois pares de tautômeros com m/z 465 [M+H]+ e m/z 449 [M+H]+. Esses produtos foram acetilados com piridina/anidrido acético e espectros de massas desses produtos indicam adição de grupamento acetil na molécula e formação de produtos com m/z 507 [M+H]+ e m/z 491 [M+H]+. Esses compostos foram reagidos com dGuo e obtivemos dois produtos com m/z 632 [M+H]+ e m/z 683 [M+H]+, sendo os possíveis adutos. A partir do composto não clorado com m/z 449 obtido após redução com ditionito de sódio, sintetizamos o análogo clorado (PBTA) após reação de cloração. Espectros de massa confirmam a formação do composto clorado com m/z 483 [M+H]+. Também incubamos o corante CI DB 291 com nitrorredutase/NADH. Análises por HPLC/ESI/MS indicam a formação de não-ClPBTA (m/z 449). Uma vez que não-ClPBTAs são mais mutagênicos para linhagens de S. typhimurium (com fração S9) que seus dinitrofenilazo corantes precursores, a conversão enzimática do corante para não-ClPBTAs pode ser uma via importante para sua bioativação.C.I. Disperse Blue 291 (C.I. DB 291) is a dinitrobromoaminoazobenzene dye with mutagenic activity to S. typhimurium, that is increased in the presence of nitroreductase, o-acetyltransferase and microsomal enzymes (S9). In this study were isolated and characterized four products of the reduction of DB 291 with sodium dithionite (in vitro), named non- chlorinated 2- phenylbenzotriazoles (non-ClPBTAs). The absorbance spectra do not present the peak corresponding to the band of azo bond (λ= 613 nm), indicating that the reduction of this bond occured. Mass spectra and 1H NMR show that the products are two pairs of tautomers with m/z 465 [M+H]+ and m/z 449 [M+H]+. These compounds were acetylated with pyridine/acetic anhydride and their mass spectra indicate the addition of an acetyl group to the molecules and formation of products with m/z 507 [M+H]+ e m/z 491 [M+H]+. After reaction of these compounds with dGuo we have got two products with m/z 632 [M+H]+ and m/z 683 [M+H]+, which are possible adducts. Starting from the non chlorinated compound with m/z 449, obtained through the dye reduction with sodium dithionite, we have synthesized the chlorinated analogous (PBTA) after chlorination reaction. Mass spectrum confirms formation of the chlorinated product with m/z 483 [M+H]+. The DB 291 dye was also incubated with nitroreductase NADH. HPLC/ESI/MS analyses indicate the formation of a non chlorinated PBTA (m/z 449). Since non- chlorinated PBTAs are more mutagenic to S. typhimurium strains (with S9 mix) than the parent phenylbenzotriazole dye, enzymatic conversion of this type of dye non chlorinated PBTAs may be an important way for its bioactivation.
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Gómez, Vallejo Vanessa. "Development of new strategies for the synthesis of radiotracers labeled with short-lived isotopes: application to 11C and 13N." Doctoral thesis, Universitat Ramon Llull, 2010. http://hdl.handle.net/10803/9301.
Анотація:
S'ha desenvolupat una nova estratègia per la síntesi ràpida i eficient de L-[metil-11C]metionina basada en el captive solvent method. La reacció de L-homocisteína (dissolució bàsica en aigua/etanol 1:1) amb [11C]CH3I en un loop de HPLC va permetre la formació del radiotraçador desitjat amb elevat rendiment radioquímic (38.4 ± 4.1%) en un temps curt (< 12 min). Tots el paràmetres analítics compleixen les especificacions requerides per la versió actual de la Farmacopea Espanyola, tot i que els valors d'activitat específica obtinguts van ser relativament baixos. Degut a això, es van estudiar i quantificar les principals fonts que contribueixen a la contaminació de carboni-12 durant les síntesis de [11C]CH3I efectuades segons el "wet" method. Es va observar que la principal font de contaminació de CO2 no radioactiu (contribució>90%) és el propi procés de bombardeig, probablement degut a la combustió (causada per les altes temperatures i pressions assolides durant la irradiació) dels compostos que contenen carboni i que es troben al gas irradiat (o a l'interior del blanc). Es van establir procediments generals per realitzar abans, durant i després de la radiosíntesi per prevenir la contaminació exterior i, d'aquesta manera, augmentar l'activitat específica dels radiotraçadors sintetitzats.En quant al marcatge amb nitrogen-13, s'ha desenvolupat un procés totalment automàtic per a la producció de [13N]NO2- a partir de [13N]NO3- generat en el ciclotró. El precursor radioactiu [13N]NO2- s'ha utilitzat per la radiosíntesi de compostos amb interès biològic com ara S-nitrosotiols (donadors de NO.), N-nitrosamines (molècules amb potencials efectes carcinogènics) i azo compostos (amb possible aplicació com a radiotraçadors per a la detecció in vivo de plaques de β-amiloide). En tots els casos es van obtenir excel·lents conversions radioquímiques (48.7% - 74.5% per S-[13N]nitrosotiols, 45.6% - 53.4% per N-[13N]nitrosamines i 40.0% - 58.3% per 13N-azo compostos) i bons rendiments radioquímics (33.8% - 60.6% per S-[13N]nitrosotiols, 34.0% - 37.8% per N-[13N]nitrosamines i 20.4% - 47.2% per 13N-azo compostos). A més a més, s'ha dissenyat i implementat un mòdul automàtic amb control remot pel marcatge de molècules amb 13N.
Se ha desarrollado una nueva estrategia para la síntesis rápida y eficiente de L-[metil-11C]metionina basada en el captive solvent method. La reacción de L-homocisteína (disolución básica en agua/etanol 1:1) con [11C]CH3I en un loop de HPLC permitió la formación del radiotrazador deseado con elevado rendimiento radioquímico (38.4 ± 4.1%) en un tiempo corto (< 12 min). Todos los parámetros analíticos cumplían las especificaciones requeridas por la versión actual de la Farmacopea Española, aunque los valores de actividad específica obtenidos fueron relativamente bajos. Por ello, se estudiaron y cuantificaron las principales fuentes que contribuyen a la contaminación de carbono-12 durante las síntesis de [11C]CH3I efectuadas según el "wet" method. Se observó que la principal fuente de contaminación de CO2 no radiactivo (contribución>90%) es el propio proceso de bombardeo, probablemente debido a la combustión (causada por las altas temperaturas y presiones alcanzadas durante la irradiación) de los compuestos que contienen carbono y que se encuentran presentes en el gas irradiado (o en el mismo cuerpo del blanco). Se establecieron procedimientos generales para realizar antes, durante y con posterioridad a la radiosíntesis para prevenir la contaminación exterior y, de esta manera, aumentar la actividad específica de los radiotrazadores sintetizados.
Respecto al marcaje con nitrógeno-13, se ha desarrollado un proceso totalmente automático para la producción de [13N]NO2- a partir del [13N]NO3- generado en el ciclotrón. El precursor radiactivo [13N]NO2- se ha utilizado para la radiosíntesis de compuestos con interés biológico tales como S-nitrosotioles (donadores de NO.), N-nitrosaminas (moléculas con potenciales efectos carcinogénicos) y azo compuestos (con posible aplicación como radiotrazadores para la detección in vivo de placas de β-amiloide). En todos los casos se obtuvieron excelentes conversiones radioquímicas (48.7% - 74.5% para S-[13N]nitrosotioles, 45.6% - 53.4% para N-[13N]nitrosaminas y 40.0% - 58.3% para 13N-azo compuestos) y buenos rendimientos radioquímicos (33.8% - 60.6% para S-[13N]nitrosotioles, 34.0% - 37.8% para N-[13N]nitrosaminas y 20.4% - 47.2% para 13N-azo compuestos). Además, se ha diseñado e implementado un módulo automático con control remoto para el marcaje de moléculas con 13N.
A new strategy for the fast and efficient synthesis of L-[methyl-11C]methionine based on the captive solvent method has been developed. The in loop reaction of a basic water/ethanol 1:1 solution of L-homocysteine with [11C]CH3I led to the formation of the desired radiotracer with high radiochemical yield (38.4 ± 4.1%) in short production time (< 12 min). All analytical parameters were within the specifications of the current version of the Spanish Pharmacopoeia, although specific radioactivity values were relatively low. Thus, the main sources of carbon-12 during the synthesis of [11C]CH3I by the "wet" method were studied and the contribution attributable to each individual source was quantified. The most relevant contamination of non-radioactive CO2 (contribution>90%) was shown to be generated during the bombardment process, probably due to the combustion (caused by high temperature and pressure during irradiation) of carbon carrier compounds present in the irradiated gas (or target body). General procedures to be performed before, during and after the radiosynthesis were established to prevent external contamination and to improve the specific radioactivity of 11C-labeled radiotracers synthesized from [11C]CH3I produced via the "wet" method.
Concerning 13N-labeling, a fully automatic process for the production of [13N]NO2- from cyclotron generated [13N]NO3- has been developed. The radioactive precursor [13N]NO2- has been used for the synthesis of biologically interesting 13N-labeled compounds such as S-nitrosothiols (well-known NO. donors), N-nitrosamines (molecules with potent carcinogenic effects) and azo compounds (with putative application as imaging probes for in vivo detection of β-amyloid plaques). In all cases, excellent radiochemical conversion (48.7% - 74.5% for S-[13N]nitrosothiols, 45.6% - 53.4% for N-[13N]nitrosamines and 40.0% - 58.3% for 13N-labeled azo compounds) and good radiochemical yields (33.8% - 60.6% for S-[13N]nitrosothiols, 34.0% - 37.8% for N-[13N]nitrosamines and 20.4% - 47.2% for 13N-labeled azo compounds) were achieved. An automatic remote controlled synthesis module for the preparation of 13N-labeled structures has been designed and implemented.
29
Moreira, Juliana. "Eletrogeração de peróxido de hidrogênio (H2O2) em eletrodos de difusão gasosa (EDG) modificados com quinonas (metil-p-benzoquinona, antraquinona-2-ácido carboxílico e ácido antraflávico) e azocomposto (Sudan Red 7B)." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/75/75135/tde-14032019-100953/.
Анотація:
Os processos oxidativos avançados (POA) são uma alternativa para complementar os processos clássicos de tratamento de efluentes que podem não ser eficientes para remoção de alguns tipos de poluentes como, por exemplo, os poluentes emergentes. Os POA se baseiam na geração de espécies altamente reativas (radicais hidroxila), a partir de peróxido de hidrogênio (H2O2), que oxidam os poluentes. O H2O2 pode ser eletrogerado in situ pela reação de redução de oxigênio (RRO) no meio reacional. O uso de eletrodos de difusão gasosa (EDG) altamente porosos proporciona o suprimento de oxigênio na interface eletrodo/solução podendo aumentar a velocidade da RRO. O uso de modificadores como quinonas e azocompostos imobilizados à matriz de carbono dos EDG podem aumentar a geração de H2O2. Portanto, os modificadores orgânicos Sudan Red 7B (SR7B), metil-p-benzoquinona (MPB), ácido antraflávico (AA) e antraquinona-2-ácido carboxílico (A2CA) foram adicionados em diferentes teores ao carbono Printex L6 (CP) e microcamadas porosas destes materiais foram estudados por voltametria cíclica e de varredura linear em eletrodo de disco-anel rotatório (RRDE). Os materiais contendo 0,5% de SR7B e 5,0% de MPB levaram a aumento na eficiência de geração de H2O2 para 86,2 e 85,5%, respectivamente, em relação ao CP puro que levou a 82,8%. EDG de CP modificados com 0,5% de SR7B foram construídos com telas metálicas em sua faces externas e a aplicação de densidades de corrente de 75, 100 e 150 mA cm-2 levou a uma maior eletrogeração de H2O2. Em densidades de corrente de 75 mA cm-2, o EDG modificado gerou 1020,1 mg L-1 de H2O2 com consumo energético de 118,0 kWh kg-1 de H2O2, constante cinética aparente de 37,3 mg L-1 min-1 e eficiência de corrente de 17,9%, enquanto o EDG de CP puro gerou menor concentração de H2O2; 717, 3 mg L-1, com maior consumo energético; 168,5 kWh kg-1, menor constante cinética aparente; 21,4 mg L-1 min-1, e menor eficiência de corrente; 12,6%. Portanto, o EDG modificado poderia ser empregado em sistemas que precisem de altas gerações de H2O2.The advanced oxidation processes (AOP) are an alternative to the classical processes of treatment of effluents that may not be effective for the removal of some types of pollutants such as emerging pollutants. The AOP are based on the highly reactive species (hydroxyl radicals) from hydrogen peroxide (H2O2), which oxidize pollutants. H2O2 can be electrogenerated in situ by the oxygen reduction reaction (ORR) in the reaction medium. The use of highly porous gas diffusion electrodes (GDE) provides the supply of oxygen at the electrode/solution interface, which can increase the RRO speed. The use of modifiers such as quinones and azocompounds immobilized on the carbon matrix of GDE may increase H2O2 generation. Therefore, the organic modifiers Sudan Red 7B (SR7B), methyl-p-benzoquinone (MPB), anthraflavic acid (AA) and anthraquinone-2-carboxylic acid (A2CA) were added in different contents to carbon Printex L6 (CP) and microporous layers of these materials were studied by cyclic voltammetry and linear sweep voltammetry on a rotating ring- disc electrode (RRDE). Materials with 0.5% of SR7B and 5.0% of MPB increased the current efficiency for electrogeneration of H2O2 to 86.2 and 85.5%, respectively, in relation to pure CP that leaded to 82.8%. GDE of CP modified with 0.5% of SR7B were constructed with metallic screens on their outer faces and an application of current densities of 75, 100 and 150 mA cm-2 led to a greater electrogeneration of H2O2. At current densities of 75 mA cm-2, the modified GDE generated 1020.1 mg L-1 of H2O2 with energy consumption of 118.0 kWh kg-1 of H2O2, apparent kinetic constant of 37.3 mg L-1 min-1 and current efficiency of 17.9%, while GDE of pure CP generated lower H2O2 concentration; 717, 3 mg L-1, with higher energy consumption; 168.5 kWh kg-1, lower apparent kinetic constant; 21.4 mg L-1 min-1, and lower current efficiency; 12.6%. Therefore, the modified GDE could be applied in systems that require high generations of H2O2.
30
Bandini, Elisa <1966>. "Biologically Active Compounds Via 2-Aza-1,3-Dienes." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/476/1/PhD_Thesis_BANDINI_ELISA.pdf.
31
Bandini, Elisa <1966>. "Biologically Active Compounds Via 2-Aza-1,3-Dienes." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/476/.
32
Lo, Kai-yip, and 羅啟業. "Synthesis of aza-bicyclic compounds via palladium-catalyzed cascade cyclization reactions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B47849691.
Анотація:
A palladium-catalyzed oxidative cascade cyclization reaction has been developed to prepare pyrrolizidine and indolizidine derivatives from simple aliphatic alkenyl amides 2.1ak in one step in moderate to good yields, using Pd(TFA)2 as the catalyst and molecular oxygen (1 atm) as a green oxidant. This cascade cyclization can also proceed for ring-containing unsaturated amides 2.1ln to afford azatricyclic systems.
Palladium(II)-catalyzed dehydrohalogenation cascade cyclization reactions have been developed to synthesize polycyclic pyrrolizidine derivatives from iodoalkenylanilides 4.1ai in satisfactory to excellent yields under mild conditions. This reaction produces two stereocenters in one step and only one single diastereomer was obtained in the cyclization of 4.1. The reaction is proposed to proceed through an organopalladium(IV) species, formed by oxidative addition after the aminopalladation. This organopalladium(IV) species then undergoes reductive elimination to give the cyclized product. This cyclization is a fast and efficient way to construct natural alkaloids that contain pyrrolizidine or indolizidine cores.published_or_final_version
Chemistry
Doctoral
Doctor of Philosophy
33
Domingo, Olwen Charlotte. "Triquinylamines & aza-cage compounds as neuronal calcium flux modulators / Olwen Domingo." Thesis, North-West University, 2008. http://hdl.handle.net/10394/4001.
Анотація:
The group of disorders that are generally characterised by changes in the normal function of neurons, also referred to as neurodegenerative conditions, are known to follow various underlying molecular pathways. With the pathogenesis of these molecular pathways gradually being elucidated, targets are being identified for the prevention of several diseases that involve the death of neurons. One of these molecular pathways involves the overload of neuronal cells with intracellular calcium ions. Since this may eventually lead to excitotoxicity, the block of calcium flux through the ion channels with the highest calcium ion permeability may thus serve as a major step towards the prevention of neurodegeneration.
In this study, the /V-methyl-D-aspartate receptor (NMDAR) ion channel and voltage-gated calcium channels served as primary targets for an inhibition of the flux of calcium ions into neuronal cells. The triquinylamines share structural similarities with existing NMDAR antagonists. These similarities include the three linearly fused cyclopentane rings that serve as lipophilic moiety, as well as the nitrogen atom that forms a hydrogen bond with amino acids in the binding site. In addition to these characteristics that might define them as NMDAR antagonists, the triquinylamines also share structural similarities to the pentacycloundecane cage compounds. In view of previous findings on the NMDAR and calcium channel blocking activity of several pentacycloundecyl amines, it was thus envisaged that the triquinylamines would present similar results. The main aim of this investigation was thus to perform structure-activity analyses between the pentacycloundecylamines and triquinane derivatives with regard to their respective NMDAR and calcium channel blocking activities.
Flash vacuum pyrolysis of the cage dione and subsequent hydrogenation yielded the saturated form of the triquinane dione. Reductive amination of this dione, using sodium borohydride, yielded the aza-triquinylamines. Aza-cage compounds were also obtained by reductive amination, but by using sodium cyanoborohydride as reducing agent instead. An additional compound, the lactol derivative of the triquinanes, was synthesised by reducing the triquinane dione with sodiumborohydride. Purification of reaction mixtures was done by means of either open column chromatography or by using a Versaflash system. Identification of the compounds was achieved by means of Nuclear Magnetic Resonance (NMR), Mass Spectrometry (MS) and Infrared (IR) techniques.
Confocal laser scanning microscopy, together with Fluo-5N and the SHSY-5Y cell line to measure calcium flux, unfortunately did not deliver reproducible results. The ratiometric dye, Fura-2/AM, in combination with a microplate reader with undifferentiated PC-12 rat phaeochromocytoma cells proved to be more effective and adequate in measuring the extent of calcium flux into the cells after KCI-stimulated depolarisation.
An interesting observation made with all the aza-bridgehead compounds as well as with NGP1-01, was their tendency to increase intracellular calcium levels at low concentrations. This was accompanied by calcium flux suppression at higher concentrations. This dualistic feature of these compounds can be attributed to activity on both the sigma receptors and calcium channels, as the PC-12 cells distinctly express both these pharmacological entities. Another surprising observation was the increased calcium influx in the presence of increasing lactol triquinane derivative concentrations. These results suggest that the lactol / hemiacetal might have the ability to antagonise ovreceptors and / or stimulate o2-receptors, as both these effects could lead to calcium level increases.
In order to determine a more specific site of action for these compounds, a competition radioligand binding study was performed. The potent phencyclidine binding site blocker, [3H]MK-801, served as reference compound in this study. The binding of [3H]MK-801 remained fairly constant in the presence of increasing concentrations of the test compounds, indicating that they exert their calcium modulating effect by binding to a site other than the phencyclidine binding site of the NMDA receptor ion channels.
This study confirms the potential of the polycyclic structures as lead compounds in the search for molecules that prevent neuronal death due to apoptosis. Their dualistic effects, as well as the possibility of sigma receptor activity provide new avenues for investigation in the search for biological lead compounds amongst the polycyclic compounds. This places an emphasis on the necessity of further studies on these potential therapeutic agents as neuroprotectors. With the new observations in biological activity for the triquinanes and pentacycloundecylamines in the current study, the possibility of a diversion in structure-activity relationship studies can also be expected in future investigations on this group of molecules.Thesis (M.Sc. (Pharmaceutical Chemistry))--North-West University, Potchefstroom Campus, 2009.
34
Olexová, Barbora. "Rozklady organických barviv metodami AOP." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-216782.
Анотація:
This diploma thesis is focused on the study of the influence of advanced oxidation processes on degradation of organic dyes. The field of AOP – very effective physically-chemical methods of wastewater treatment – includes application of strong oxidation agents, UV and ionizing radiation and electrical discharges. For this thesis, two of these methods were chosen – the application of oxidation agent (ozone) and UV radiation. Along with electrolysis, which is mentioned rather marginally in this thesis (it is the subject of the previous thesis), these phenomena are products of electrical discharge in water, where they participate in the processes of degradation in a different way. For all measurement series, two direct azo dyes were chosen as model substances – C.I. Direct Blue 106 and C.I. Direct Red 79. The ozonizer, in which either oxygen or synthetic or technical air were loaded as carrier gases, was used for degradation of dyes by ozone. The generated ozone was loaded into the bubbling vessel with dye solution of different initial concentration (10–130 mg.dm-3), which was followed by other bubbling vessel with KI solution for the next analytical determination of the amount of generated ozone. The other parameters changed were the gas flow (1–2 dm3.min-1), ozonizer output (minimal and maximal), type of dye, pH value of the solution (neutral or acid) and additional electrolyte (NaCl, Na2SO4 or any). The reactor for the study of the influence of UV radiation on degradation of dyes was an UV sterilizer into which the equivalent volume of dye solution was added. The possibilities of experimental settings were limited and only the type of dye, an additional electrolyte and pH value of the dye solution were adjusted (as in the case of ozone). Several series of samples were measured with various input conditions which more or less influenced the degradation of investigated dyes in this experiment. It was found that for both used methods the Direct Blue 106 dye was more degradable (with significantly better results for ozone than for UV radiation). The degradation of Direct Red 79 dye proceeded only by ozone treatment, in the case of the application of UV radiation no degradation occurred. By investigation of the influence of initial concentration of dye on its degradation, it was confirmed that with the initial concentration enhancement the final concentration rises as well, whereas in low concentrations (10–50 mg.dm-3) the initial concentration has no effect. The addition of an electrolyte had an accelerating effect on dye degradation in both methods (NaCl and also Na2SO4 showed similar results though the degradation proceeded in different ways). The addition of HCl accelerated the degradation only in the case of UV radiation; during the application of ozone the pH level of the system did not have any influence on the degradation. Oxygen and synthetic air had the strongest effect on ozone degradation (comparable results); in the case of technical air the final dye concentration was higher up to 30 %. The gas flow of 1.5 dm3.min-1 was stated as optimal with the ozonizer output 30 W (maximal). At minimal power the ozonizer produced very low amount of ozone.
35
Matzner, Robert Allan. "Characterization of aza-arene transport in saturated porous media." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/191179.
Анотація:
Several factors which affect the transport of pyridine, quinoline and acridine (aza-arenes) in saturated porous media were investigated in laboratory experiments in order to provide data for input into coupled models that may be applied to predicting the fate of these compounds in groundwater. The effect of pH and ligand type and concentration on acridine solubility was studied in a series of batch and pH-stat experiments. There was a decrease in acridine solubility below the compound's pKₐ due to acridine/ligand precipitate formation. The reaction stoichiometry and solute/sorbent interactions of aza-arene adsorbed to porous silica were determined from batch adsorption and Raman spectroscopy experiments. The neutral aza-arene was hydrogen bonded to surface sites above the compound's pKₐ and there was a cation/ClO₄⁻ complex interacting with surface sites through dipole-dipole interactions below the pKₐ of the compound. The effect of pH, temperature, ligand type, average linear velocity and initial aqueous phase solute concentration on the adsorption of aza-arenes to porous silica was investigated in a series of column experiments. The extent of adsorption followed the trend pyridine < quinoline < acridine due to greater overlap of the molecule with adsorption sites as the number of rings increases. The extent of adsorption was greater below the compound's pKₐ than above because the complex was able to optimize its orientation with the surface. The extent of adsorption of neutral acridine was enhanced when carbonate was used as a buffer relative to phosphate due to carbonate's more exothermic hydration enthalpy. The isotherms were non-linear above and below the pKₐ of acridine. The enthalpy of the adsorption reaction was less exothermic below the compound's pKₐ than above due to the stronger hydrogen bonds formed between the surface and the neutral molecule compared to the dipole-dipole interactions that bond the complex to the surface below the pKₐ. Non-equilibrium effects on the adsorption reaction were minor. Adsorption-desorption was on the order of seconds to minutes. Kinetic effects became more important as temperature decreased.
36
Gheura, Iuliana L. "Design, synthesis and evaluation of AZA-peptide epoxides as inhibitors of cysteine proteases." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/30571.
37
Daddario, Cassie M. "Synthesis and Optoelectronic Properties of Electron Accepting Azadipyrromethene-based Compounds." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1444768936.
38
Roberts, Craig A. "The application of tin compounds to biaryl bond formation and the AZA-[2,3]-Wittig rearrangement." Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267070.
39
Wu, Shu-Pao. "Iron-sulfur cluster biosynthesis. Iron-sulfur cluster transfer from holo ISU and ISA to apo ferredoxin." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1078866123.
Анотація:
Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xx, 161 p.; also includes graphics Includes bibliographical references (p. 153-161). Available online via OhioLINK's ETD Center
40
Delatour, Thierry. "Mise en évidence par spectrométries optiques de formes tautomères caractéristiques d'un pyridylazo diethylaminophénol." Nancy 1, 1987. http://www.theses.fr/1987NAN10159.
Анотація:
Étude des structures tautomériques du (bromo-5 pyridyl-2-azo)-2 diethylamino-5 phénol par spectrométrie ir, visible, d'émission visible et de diffusion raman de résonance. Attribution des transitions électroniques et vibrationnelles principales. Seules les structures quinoniques sont observées, la forme azo n'apparaissant pas en quantité détectable
41
Criton, Thomas. "Systèmes polyazotés énergétiques : stratégie de synthèse, caractérisation et réactivité." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1222.
Анотація:
Les hydrazines utilisées en propulsion sont aujourd’hui identifiées par la réglementation REACH comme des substances extrêmement préoccupantes (SVHC) et leur utilisation est par conséquent menacée. Les HEDM (High Energy Density Material) représentent une classe de composés à l’architecture polyazotée voire strictement azotée dont les performances énergétiques théoriques sont en rupture avec les technologies actuelles et dont la décomposition en N2 offrirait une réponse à cette règlementation. De plus, leur utilisation simplifierait la technologie des lanceurs et permettrait d’abaisser leur coût. Deux candidats potentiels ont donc été proposés par les tutelles du laboratoire en raison de leurs excellentes performances théoriques : la triaziridine (N3H3) et la tétrazétidine (N4H4). L’objectif général de cette thèse est de développer de nouvelles méthodologies de synthèse de composés polyazotés et d’étudier leur réactivité afin de valider l’accès aux structures originales telles que les cycles triaziridine et tétrazétidine. Une toute nouvelle méthodologie d’homologation par ajout d’azodicarboxylates permettant d’accéder à des systèmes polyazotés linéaires supérieurs (N3, N4, N5, N6…) a été mise au point. Des preuves structurales de ces enchainements azotés inédits ont été obtenues par DRX. La réactivité par activation régiosélective et par oxydation des systèmes synthétisés a ensuite été étudiée afin d’accéder aux structures polyazotées cycliquesHydrazines for propulsion have been identified by REACH regulation as Substances of Very High Concern (SVHC) and their use is therefore threatened. High Energy Density Materials (HEDM) represent a class of polynitrogen compounds with computed energetic performances breaking away from existing technologies. Besides solving toxicity issues thanks to their decomposition in molecular nitrogen, their use would highly simplify launcher’s technologies and decreases their cost. Two candidates have been proposed by the CNES and ArianeGroup to replace hydrazines: triaziridine (N3H3) and tetrazetidine (N4H4). The main goal of this thesis is to develop new methodologies for the synthesis of polynitrogen compounds and to investigate their reactivity to access to original structures such as triaziridine and tetrazetidine. Homologation of simple nitrogen-based compounds with azodicarboxylates enabled us to access new original superior polynitrogen molecules (N3, N4, N5, N6…). Structural evidences of these new polynitrogen backbones have been obtained by X-ray diffraction. Their reactivity by regioselective activation and by oxidation has been studied to access cyclic polynitrogen structures
42
Fadelalla, Ali Mohamad Mohamad. "Manganese(iii)acetate-based Free-radical Additions Of -dicarbonyl Compounds To Bicyclic Systems." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12608402/index.pdf.
Анотація:
Additions of carbon-centered radicals to alkenes are useful method for cyclic compounds formation. Manganese(III)-based oxidative free-radical cyclizations, where the radicals are generated and terminated oxidatively, are established as efficient methods for the construction of cyclic molecule.
Treatment of a mixture of dimedone, Mn(OAc)3, and Cu(OAc)2 in glacial acetic acid with homobenzonorbornadiene (80) (4h at 50 
C) gave furan derivative (107), dihydrofuran adduct (108), in addition to rearranged product (109) as a major product. The reaction run under the same reaction conditions without using Cu(II)acetate for 8h afforded dihydrofuran adduct (108) along with dihydrofuran (110), where no rearranged products could be formed. On the other hand, reflux of alkene 80 with a mixture of acetylacetone, Mn(OAc)3, and Cu(OAc)2 in glacial acetic acid (3h at 50 &
#61616
C) gave oxidative product (131) and rearranged product (132) (major). The reaction run under the same reaction conditions without using Cu(II)acetate for 7h produced, in addition to the oxidative product 131, a dihydrofuran derivative (133). In a second system, we examined the oxidation of benzobarrelene 82 with Mn(OAc)3, and Cu(OAc)2 in glacial acetic acid (1h at 50 &
#61616
C) in presence of dimedone resulted in the formation of five different products rearranged products (148, 149) and a dihydrofuran (109), besides, a mixture containing two major rearranged isomers (150/151). The same reaction was carried out under the same conditions in absence of Cu(II) for 9h and gave the isomeric mixture 150/151 exclusively, and the yield was reduced. The oxidative cyclization of acetylacetone with alkene 82 for 3h at 50 &
#61616
C, afforded in addition to the dihydrofuran (132), two rearranged products (169, 170) and a mixture consisting of two isomers (171/ 172). The isomeric mixture was converted to one product by treatment with methanolic ammonia providing hydroxyl derivative which was oxidized by MnO2 to afford product 174 in a good yield. Additionally, we investigated the behavior of nitrogen bridge in the bicyclic system on the course of the reaction. Oxidation of N-carbethoxy-7-aza-2,3-benzonorbornadiene 83 with dimedone in the presence of Cu(OAc)2 as well as in its absence in glacial acetic acid (2h at 50 &
#61616
C), rearranged product (189) was obtained as the sole product. Regarding the reaction of aza-derivative 83 with acetylacetone in the presence of Cu(OAc)2 (18 h at 50 &
#61616
C), rearranged product 195 was resulted as sole product. The reaction of 83 was also run with out Cu(OAc)2 for 22h and gave the rearranged product 195.
43
Huez, Philippe. "Synthèses et analyses conformationnelles de macrocycles aza-β³-peptidiques contenant des atomes d'azote chirogéniques". Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S072/document.
Анотація:
Le travail présenté dans ce mémoire est consacré à la synthèse de cycles pseudopeptidiques construits à partir d'aza-β³-aminoacides, et à la détermination des conformations adoptées par ces cycles. Le travail réalisé a permis de montrer que les cycles obtenus à 8, 16 et 24 liaisons adoptent des conformations privilégiées dans lesquelles la configuration relative des atomes d'azote chiraux est fixée en dépit du phénomène d'inversion pyramidale associé à la structure électronique de cet élément chimique, en réponse à des contraintes structurelles qui varient selon la taille du macrocycle. Ces cycles existent alors sous la seule forme de deux invertomères en équilibre. La constante de vitesse de cet équilibre, qui est indiscernable de la barrière d'inversion pyramidale des atomes d'azote, est maintenue à des valeurs étonnamment faibles par les contraintes conformationnelles. L'étude de ces macrocycles originaux dans le domaine de la chiralité a permis d'apporter en particulier des résultats nouveaux concernant l'influence de l'encombrement stérique des chaînes latérales sur la vitesse d'inversion pyramidale des atomes d'azote, mais aussi sur le transfert de chiralité d'éléments d'asymétrie exocycliques vers la séquence chirale du squelette, et enfin de montrer également l'intérêt des nouveaux cycles à 8 chaînons à travers l'étude de leur conformationThe work depicted here is devoted to the synthesis of pseudopeptides built from aza-β³-aminoacid units, and to their conformational analysis. The results show that the cycles with 8, 16, and 24 bonds each adopt a ground conformation where the relative configuration of the chiral nitrogen atom is fixed in response to specific structural constraints, and despite the nitrogen pyramidal inversion phenomenon. The cycles just undergo equilibrium between two invertomeric forms, and the energetic barrier associated with the macrocycle inversion reveals surprisingly slow considering the size of the compounds. The influence of steric crowding of the side chains on the inversion rate has been carefully studied, but also the transfer of chirality from exocylic elements towards chirotopic nitrogen atoms inside the backbone. A specific chapter is devoted to the 8-membered rings, that reveal the interest of these newly described compounds in the domain of nitrogen chirality
44
Cui, Chunming. "Aluminum (I, II, III) Compounds with Multidentate Ligands: Syntheses, Reactivity, and Structures." Doctoral thesis, [S.l. : s.n.], 2001. http://webdoc.sub.gwdg.de/diss/2001/cui/cui.pdf.
45
Mojica, Mike. "Investigation of new synthetic reactions: the synthesis of hydrazines via the Aza-Lossen rearrangement, the synthesis of carbamoyl azides from amines, and deprotection reactions using water at elevated temperatures." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51791.
Анотація:
This thesis explores three rare synthetic routes: the synthesis of hydrazines via the aza-Lossen rearrangement, the synthesis of carbamoyl azides from amines, and deprotection reactions using water at elevated temperatures. The aza-Lossen reaction was found to be ideal at “infinite dilution” conditions and could be performed with both aryl and alkyl example. Carbamoyl azides could be synthesized in high yields from both aryl and alkyl amines. The carbamoyl azide reaction was found to be much more efficient with Cs (+1) present. Lastly, water at elevated temperatures conditions was efficient at removing various amine and hydroxyl protecting groups.
46
Grosser, Fabiana Nogueira. "inibidores orgânicos de corrosão : estudos com compostos naturais obtidos de diversas espécies de mentas." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/129769.
Анотація:
O comportamento eletroquímico do aço carbono em soluções aquosas contendo KNO3 0,10 mol L-1 e soluções etanólicas contendo cloreto de tetraetilamônio 0,10 mol L-1 foi estudado na ausência e na presença de diferentes concentrações (0,50 mM a 50,0 mM) de acetato de linalila, mentol, limoneno e pulegona. Técnicas eletroquímicas como a potenciometria, varredura potenciodinâmica, cronoamperometria, curvas de Tafel e espectroscopia de impedância eletroquímica foram utilizadas a fim de compreender a interação entre os compostos orgânicos e a superfície do eletrodo. Medidas de perda de massa também foram realizadas, bem como a comprovação visual dos resultados mediante registros fotográficos. O acetato de linalila adsorve na superfície do aço carbono mesmo na presença de grande quantidade de água ou etanol. A energia livre de adsorção de Gibbs para este processo é de -26,0 kJ mol-1 em soluções aquosas e -26,7 kJ mol-1 em soluções etanólicas. Para o mentol, a energia livre de adsorção de Gibbs calculada foi de -26,7 kJ mol-1 em soluções aquosas e -24,2 kJ mol-1 em soluções etanólicas. Para o limoneno, esses valores foram -24,2 kJ mol-1 em meio aquoso e -26,0 kJ mol-1 em meio etanólico, e para a pulegona os valores foram de -25,7 kJ mol-1 e -24,6 kJ mol-1, em meio aquoso e etanólico, respectivamente. Foi detectado que as espécies adsorvidas na superfície do metal diminuíram os valores das densidades de corrente anódicas, bem como a perda de massa do metal. Esses efeitos permitem-nos classificar esses compostos orgânicos como inibidores naturais de corrosão para o aço carbono em soluções aquosas e etanólicas.The electrochemical behavior of low carbon steel in aqueous solutions containing KNO3 0.10 mol L-1 and ethanolic solutions containing tetraethylammonium chloride 0.10 mol L-1 was studied in the absence and presence of different concentrations (0.50 mM to 50.0 mM) of linalyl acetate, menthol, limonene and pulegone. Electrochemical techniques such as potentiometry, cyclic voltammetry, chronoamperometry, Tafel curves and electrochemical impedance spectroscopy were used to understand the interaction between the organic compound and the electrode surface. Weight loss measurements were also performed, as well as visual confirmation of the results by photographic records. Linalyl acetate adsorbed on low carbon steel surface even in the presence of a large amount of water or ethanol. The Gibbs free energy of adsorption for this process was -26.0 kJ mol-1 in aqueous solutions and -26.7 kJ mol-1 for ethanol solutions. For menthol, the Gibbs free energy of adsorption was calculated -26.7 kJ mol-1 in aqueous solutions and -24.2 kJ mol-1 for ethanol solutions. For limonene, these values were -24.2 kJ mol-1 in aqueous medium and -26.0 kJ mol-1 in ethanolic medium, and for pulegone the values were - 25.7 kJ mol-1 and -24.6 kJ mol-1 in aqueous and ethanolic medium, respectively. It was detected that the species adsorbed on the metal surface decreased the amounts of anodic current densities and the metal mass loss. These effects allow us to classify the organic compounds investigated as natural corrosion inhibitors for low carbon steel in aqueous and ethanolic solutions.
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Lorini, Alexandre. "Perfil metabolômico de folhas de cultivares de oliveiras nas diferentes estações do ano." Universidade Federal de Pelotas, 2018. http://guaiaca.ufpel.edu.br:8080/handle/prefix/4123.
Анотація:
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Considerada uma cultura milenar, a oliveira (Olea europaea L.) possui além de seu fruto, as folhas, que contêm quantidades apreciáveis de compostos bioativos, os quais estão relacionados com o sistema de defesa das plantas e com diversas ações no organismo humano. Os estresses abióticos funcionam como mecanismos de ativação das rotas de sínteses destes compostos, devido ao aumento do nível oxidativo nas plantas pela produção de radicais livres. Comumente cultivada na região do mediterrâneo, diversos programas de melhoramento foram responsáveis pela modificação e criação de novas cultivares de oliveira, para que estas pudessem ser cultivadas em toda a parte do mundo. Portanto, o objetivo deste estudo foi avaliar o perfil metabólico de folhas de cultivares de oliveira (Arbequina, Manzanilla e Picual) coletadas em nas diferentes estações do ano (outono, inverno, primavera e verão) em Pinheiro Machado/RS durante 2016/17. Foram realizadas por espectrofotometria a determinação de compostos fenólicos, flavonoides, taninos, carotenoides e clorofilas, enquanto que a identificação e quantificação de fenólicos individuais, foi realizada por cromatografia líquida de alta eficiência acoplada a espectrometria de massas. Também foram realizados ensaios de potencial antioxidante pelos métodos de DPPH, FRAP e ABTS. Como resultados foi possível observar que as folhas da cultivar Manzanilla apresentaram os maiores teores de compostos fenólicos e que as folhas coletadas no verão apresentaram uma quantidade desses compostos significativamente maior que as coletadas nas outras estações. Consequentemente, os potenciais antioxidantes dos extratos polares destas folhas apresentaram alta correlação com estes compostos, sendo observado maiores potenciais nos mesmos tratamentos em que o conteúdo de compostos fenólicos se sobressaiu. Compostos polares e apolares se comportaram de maneira diferente, gerando questionamentos sobre como as vias de síntese destes compostos interagem ou se são independentes. A relação entre a finalidade da cultivar (produção de azeite ou azeitonas de mesa) e os compostos bioativos nas folhas ainda precisa ser melhor estudada, devido aos maiores níveis de compostos fenólicos e taninos hidrolisáveis encontrados na Manzanilla neste trabalho. Por fim, foi possível concluir que a cultivar e a época de coleta possuem relação significativa com o perfil metabólico de folhas de oliveira.
Considered a millenary culture, the olive tree (Olea europaea L.) has besides its fruit, the leaves, which contain appreciable amounts of bioactive compounds, which are related to the system of defense of plants and with various actions in the human organism. The abiotic stresses act as mechanisms of activation of the routes of synthesis of these compounds, due to the increase of the oxidative level in the plants by the production of free radicals. Commonly cultivated in the Mediterranean region, several breeding programs were responsible for the modification and creation of new olive cultivars, so that they could be cultivated throughout the world. Therefore, the objective of this study was to evaluate the metabolic profile of leaves of olive cultivars (Arbequina, Manzanilla and Picual) collected in the different seasons of the year (autumn, winter, spring and summer) in Pinheiro Machado / RS during 2016/17. The determination of phenolic compounds, flavonoids, tannins, carotenoids and chlorophylls were performed by spectrophotometry, while the identification and quantification of individual phenolics was performed by high performance liquid chromatography coupled to mass spectrometry. Antioxidant potential tests were also carried out using DPPH, FRAP and ABTS methods. As results it was possible to observe that the leaves of the cultivar Manzanilla presented the highest contents of phenolic compounds and that the leaves collected in the summer presented a quantity of these compounds significantly higher than those collected in the other seasons. Consequently, the potential antioxidants of the polar extracts of these leaves showed high correlation with these compounds, being observed greater potentials in the same treatments in which the content of phenolic compounds excelled. Polar and nonpolar compounds behaved differently, raising questions about how the synthesis pathways of these compounds interact or whether they are independent. The relationship between the purpose of the cultivar (oil production or table olives) and the bioactive compounds in leaves still needs to be better studied, due to the higher levels of phenolic compounds and hydrolysable tannins found in Manzanilla in this work. Finally, it was possible to conclude that the cultivar and the collection season have a significant relationship with the metabolic profile of olive leaves.
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Dhakal, Ram Chandra. "New Approaches To Heterocycle Synthesis: A Greener Route To Structurally Complex Protonated Azomethine Imines, And Their Use In 1,3-Dipolar Cycloadditions." ScholarWorks @ UVM, 2017. http://scholarworks.uvm.edu/graddis/777.
Анотація:
1-Aza-2-azoniaallene salts are reactive intermediates that undergo [3+2] cycloaddition with many different types of multiple bonds. For the past several years, the Brewer group has studied the reactivity of these intermediates in intramolecular reactions, and have discovered that these cationic heteroallenes can react through a variety of other, mechanistically distinct, pathways to give different classes of nitrogen heterocycles. For example, prior work in the Brewer group revealed that 1-aza-2-azoniaallene salts could react in an intramolecular [4+2] cycloaddition reaction to give protonated azomethine imine salts containing a 1,2,3,4-tetrahydrocinnoline scaffold. Further study of the scope and limitations of this Diels-Alder-like reaction are described herein. These studies primarily focused on how varying the N-aryl ring and alkene substituents affected the reaction. We discovered that in several instances, the metal mediated reaction did not facilitate the cycloaddition very well, so we searched for alternative ways to facilitate the reaction. We discovered that a non-metallic Lewis acid (TMSOTf) provided very clean products with α-chloroazo compounds. I hypothesized that changing the leaving group adjacent to the azo might further improve the reaction. With this in mind, I developed a technique to prepare α-trifluoroacetoxyazo compounds by treating aryl hydrazones with trifluoroacetoxy dimethylsulfonium trifluoroacetate. This technique is compatible with all types of functional groups including nitro aryl compounds, which gave low yields of the corresponding chloroazo derivatives. Importantly, these α-trifluoroacetoxyazo compounds gave even better cycloaddition results when treated with TMSOTf, and this method is more practical, more environmentally friendly, and greener than the metal mediated technique. This process even returned sterically hindered products in high yield, and provide a dearomatized non-protonated azomethine imine salt, which further verified the proposed mechanism of the [4+2] cycloaddition. Azomethine imines are well known to undergo 1,3-dipolar cycloadditions with alkenes. We wondered if the protonated azomethine imine salts generated by the [4+2] cycloaddition could be used in a subsequent base-mediated [3+2] cycloaddition to generate structurally complex tetra- or pentacyclic products. We were pleased to find that the protonated azomethine imines indeed reacted smoothly with a variety of π-system in the presence of triethylamine to give the corresponding cycloadducts in high yields with moderate to high diastereoselectivities. In an attempt to understand the diastereoselectivity of these [3+2] cycloadditions better, I modeled them computationally.
49
Ebad-Allah, Jihaan Fath-Allah Abo-Elyazeed [Verfasser], and Christine A. [Akademischer Betreuer] Kuntscher. "Tuning the electron localization in transition-metal oxide compounds: Fe3O4 and TiOCl under extreme conditions / Jihaan Fath-Allah Abo-Elyazeed Ebad-Allah. Betreuer: Christine A. Kuntscher." Augsburg : Universität Augsburg, 2013. http://d-nb.info/1077703031/34.
50
Dias, Rafael Mafra de Paula. "Adições de aza-Michael em diazocetonas α,β-insaturadas e reações de inserção em ilídeos β-cetosulfoxônios." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/75/75133/tde-23032016-092522/.
Анотація:
O trabalho de tese é dividido em dois capítulos e visou explorar a química das diazocetonas α,β-insaturadas bem como dos ilídeos β-cetosulfoxônios. No primeiro capítulo é apresentado o emprego das diazocetonas α,β-insaturadas como novos aceptores em reações de aza-Michael. A adição conjugada de aminas primárias e secundárias foi explorada, assim como o uso de aminas quirais para avaliar a versão assimétrica da reação. Além da formação desses adutos, também foram investigadas estratégias para a construção de heterocíclicos nitrogenados a partir destes ou via protocolos \"one-pot\" (partindo das diazocetonas α,β-insaturadas) levando à formação de 2- e 3-pirrolidinonas. Por fim, foi avaliada a aplicação da metodologia desenvolvida na síntese do produto natural Barmumicina. O segundo capítulo se dispôs a investigar o emprego dos ilídeos β-cetosulfoxônios como substitutos de compostos diazocarbonílicos em reações de inserção. Num primeiro momento, avaliaram-se reações de inserção S-H intermolecular, visando a construção do fragmento β-cetotioéter. Alguns estudos competitivos e mecanísticos, bem como estratégias assimétricas também compõem o escopo. Num segundo momento, os ilídeos foram empregados em reações de inserção N-H intramolecular, no qual, a partir de sulfoxônios derivados de aminoácidos, vislumbrou-se a formação de 3-azetidinonas.This thesis is divided into two chapters which are related to the chemistry of α,β-unsaturated diazoketones and β-ketosulfoxonium ylides. The first chapter presents the utility of α,β-unsaturated diazoketones as new aza-Michael acceptors. Conjugate addition of primary and secondary amines was explored, as well as the use of chiral amines to evaluate the asymmetric version of the reaction. In addition to the formation of these adducts, it was also investigated some strategies for the synthesis of 2- and 3-pyrrolidinones via the \"one-pot\" protocols (starting directly from the α,β-unsaturated diazoketones). Finally, the synthesis of the natural product Barmumicyn was evaluated from this methodology. The second chapter aimed to investigate the use of β-ketosulfoxonium ylides as diazocarbonyl compounds substitutes in insertion reactions. At first, the intermolecular S-H insertion reaction was studied aiming the construction of the β-ketothioether fragment. Some competitive and mechanistic studies, as well as asymmetric versions are also part of the scope. Secondly, some ylides were also employed in intramolecular N-H insertion reactions (from sulfoxonium amino acid derivatives) aiming the formation of 3-azetidinones.