Ce sujet entre dans le cadre de l'étude d'un procédé d'oxydation avancé innovant dans le domaine de la dépollution des eaux, à savoir l'ionisation par faisceau d'électrons. Le radical hydroxyle (•OH) et l'électron hydraté (e−aq) sont les deux espèces majoritaires issues de l'ionisation de solutions aqueuses par un faisceau d'électrons d'intense énergie. Il a été démontré que la génération des radicaux supplémentaires tels que le radical sulfate (SO4•−) et le radical hydroxyle par les réactions radicalaires entre l'ion persulfate, le peroxyde d'hydrogène et l'électron hydraté respectivement, améliore l'efficacité de ce procédé pour la dégradation de polluants organiques en solution aqueuse. Dans le présent travail, la dégradation et la minéralisation de benzènesulfonate et naphthalènesulfonate de sodium, et d'acide gallique ont été obtenues par irradiation par faisceau d'électrons seul et couplé avec un oxydant (S2O8−−, H2O2). En absence d'oxydant une dose absorbée de 1,5 kGy a été suffisante pour l'élimination totale de ces composés. La présence d'oxydant permet généralement de réduire les doses d'irradiation nécessaires. Par ailleurs, l'augmentation de la concentration en oxydant ou de la dose appliquée a un effet bénéfique vis-à-vis de l'élimination du carbone organique. Cependant, le couplage S2O8−−/faisceau d'électrons est plus adapté que le couplage H2O2/faisceau d'électrons même en présence de constituants inorganiques. Les résultats obtenus soulignent l'importance du rôle du dioxygène dissous lors de l'étape de la minéralisation en vue de favoriser la formation des radicaux organiques (ROO•). Pour chaque une des molécules étudiées, des sous-produits d'oxydation... / This research belongs to the study of the ionization of aqueous solutions by electron beam (E.B.) as an advanced oxidation process for water treatment. The hydroxyl radical (•OH) and hydrated electron(eaq¯) are the two major active species produced from the ionization of aqueous solutions by high energy electron beam. It has been shown that the generation of additional radicals such as the sulphate radical (SO4•¯) and hydroxyl radical from the reaction of persulfate ion (S2O8¯) or hydrogen peroxide (H2O2) with the hydrated electron, improved the efficiency of this process towards the degradation and mineralization of organic pollutants in aquaeous solution. In the présent work, the degradation and mineralization of naphthalenesulfonate, benzenesulfonate and gallic acid were studied by electron beam irradiation alone and coupled with oxidants (S2O8¯, H2O2).In the absence of oxidant, an absorbed dose of 1,5 kGy leads to total elimnation of these pollutants. The presence of added oxidants usually reduces the radiation dose required. In addition, increasing oxidant concentration or applied dose had a beneficial effect towards the organic carbon removal. It was found that coupling E.B./S2O8¯ has more suitable than E.B./ H2O2 even in the presence of inorganic constituents. The results also highlighted the importance of dissolved oxygen in the system when mineralization is aimed. For each of the molecules studied, oxidation by-products resulting from hydroxylation and aromatic ring opening were identified.

Philosophiae Doctor - PhD / Recently, a great deal of interest has developed towards the isolation of bioactive compounds from marine sources due to their numerous health benefits. Furthermore, marine algae are valuable sources of structurally diverse metabolites with scientifically proven therapeutic claims. The cell walls are rich in sulfated polysaccharides such as fucoidans in brown algae, carrageenans in red algae and ulvans in green algae. These sulfated polysaccharides exhibit many beneficial biological activities such as anticoagulant, antiviral, antioxidative, anticancer and immunomodulating activities. They have great potential for further development as products in cosmeceutical, pharmaceutical and nutraceutical areas. Although the mechanism of action is still not clear, their biological activities could be mainly attributed to their major secondary metabolites namely; phlorotannins, terpenoids and fucoidans. There was use of comprehensive chromatographic separations and a full analysis of isolates using one or other of the spectroscopic techniques. Antioxidant and cytotoxicity tests were perfomed in details for Ecklonia maxima. Furthermore, structural and electronic features of the phlorotannins were compared in an attempt to provide an explanation for the differences in their radical scavenging properties. In this regard, two main radical scavenging mechanisms, hydrogen atom transfer (HAT) and electron transfer (ET), were assessed in order to determine the preferred mode of radical scavenging. Fully relaxed geometry optimizations of the neutral and the radical species were performed utilizing DFT/B3LYP and DFT/UB3LYP methods respectively. In further studies, the structural and functional properties of sulfated polysaccharides from the three brown and one red seaweeds were investigated. This was through detailed analysis of chemical composition of crude and purified polysaccharides using PMP - derivatization of hydrolysed sugars, anion exchange, molecular weight determination, ion chromatography , FT-IR, NMR to methylation analysis. The work reports isolation and characterization of compounds from four algae: Ecklonia maxima, phlorotannin derivatives, namely phloroglucinol (22), eckol (23), 7-phloroeckol (24), 2-phloroeckol (25) and a sterol, 24-ethylidine cholesterol (26); Splachinidium rugosum, 24-ethylidine cholesterol ( 26), 1, 3-Dicapryloyl-2-oleoylglycerol (27), E-3,7,11,15-tetramethylhexa dec-2-en-1-ol (phytol) (2 8); Macrocystis angustifolia, 24-ethylidine cholesterol (26); a red seaweed Aeodes orbitosa, and E -3, 7, 11, 15-tetramethylhexad ec-2-en-1-ol (28) and 17-(5-Ethyl-6-methylheptan-2-yl)-10,13-dimethyl-2,3,4,7, 8,9,11,12,14,15,16,17-dodecahydro-1 H-cyclopenta[a]phenanthren-3-ol (β-sitosterol) (29). Experimental findings and theoretical predictions of phlorotannins indicated that the radical scavenging activities followed the order 22< 23 < 25 < 24. Theoretical studies further indicated the ET mechanism is more significant than the HAT mechanism due to the high BDE values. Their polysaccharide structures were tentatively shown to have a backbone of (1-3) and (1-4) linkages with sulfate groups at O-2 and O-2, 3 positions. The only red algae studied contained, 2-O-methyl-D-galactose with (1-3) and (1-4)-glycosidic linkages possessing sulfate groups at positions 2 and 6.

Tésis para optar al grado de Magister en Comunicación Política / La presente investigación pone de manifiesto la importancia de construir una definición identitaria en los partidos políticos chilenos, en cuanto a su funcionamiento como movimientos sociales institucionalizados. Considerando un contexto, donde su legitimidad cada vez se ve más cuestionada. La problemática se centra específicamente en el discurso del Partido Radical Social Demócrata, analizándolo como expresión de su identidad.. Si bien la tesis parte de una premisa de crisis identitaria, es a través de los elementos que son constantes tanto en el discurso político histórico como en el actual, termina vislumbrando que esta crisis no es tal, si no que es parte de su pensamiento como partido de centro, que abraza principios específicos - libertad, igualdad y fraternidad- antes que una ideología.

In this thesis, we explored the use of a renewable resource to produce more sustainable polymeric materials. Limonene, a monocyclic terpene existing in many essential oils extracted from citrus rinds, was the renewable monomer investigated. The d-limonene ((+)-limonene) isomer is a major component (~90%) of orange oils from orange juicing and peel processing. Having been used as a flavour and fragrance additive in cosmetics, foods and beverages, as well as a green solvent, limonene is of particular interest in polymerization, because it contains double bonds, which provide the bifunctionality necessary for polymerization. Limonene is also an allylic monomer (CH2=CH-CH2Y), which presents challenges in free-radical homopolymerization and thus, copolymerization was investigated herein to overcome this difficulty. 2-Ethylhexyl acrylate (EHA) and n-butyl methacrylate (BMA) were used in two separate projects, as comonomers with limonene. Using bulk free-radical copolymerization at 80℃, with benzoyl peroxide (BPO) as the initiator, high molecular weight (>100,000) EHA/limonene and BMA/limonene copolymers were produced. Reactivity ratios, important parameters used in the prediction of copolymer composition, were estimated and shown to accurately predict the copolymer composition of subsequent experiments. These can now be used for the application of appropriate semi-batch policies to further enhance limonene incorporation into the copolymers.

A new method for the synthesis of naphthalenes has been recently discovered. The Atom Transfer Radical Cyclisation (ATRC) of diverse 2-allylphenyl2',2',2'-trichloroacetates in the presence of a Cu complex afford schloronaphthalenes in good yields using either microwave or thermolytic methods of activation. A mechanism for the benzannulation reaction is proposed and experiments presented in order to validate this hypothesis. The use of 1,3-bis(2,6-diisopropylphenyl)imidazolium copper(I) chloride [(IPr)CuCl)] along with other metal carbenes is compared to the already reported CuCl/ligand system. Since the scope and synthetic utility of this new benzannulation reaction is restricted due to the use of the MW reactor, a solvent in which the thermal reaction can take place is reported, proving its efficiency in the synthesis of a range of substituted naphthalenes. The potential and versatility of the benzannulation reaction has been investigated. Studies towards the synthesis of gilvocarcin M which contains a tetracyclicaromatic core are presented. Gilvocarcins have potential use as anti-cancer agents and represent a member of the C-aryl glycosides found in natural products. Gilvocarcin M is a challenging target because there are a sparse number of total syntheses reported in the literature. The ATRC reaction of (vinyl)phenyl trichloroacetate has also been investigated, affording the synthesis of functionalised coumarins. The mechanism of this reaction has also been investigated, establishing that, in some cases, aretro-Kharasch reaction is observed.

The use of H2O as an additive in SmI2-mediated reductive processes provides access to new transformations and previously inaccessible chemical space. The cyclisation of radicals derived from the selective mono-reduction of Meldrum’s acid derivatives was further investigated and the scope of the methodology expanded to cyclisation cascades. The first general methodology for the reduction of amide-type carbonyls under single electron transfer conditions was developed and applied to the mono-reduction of barbituric acid derivatives, providing an unprecedented direct access to the corresponding hemiaminals with a good degree of stereocontrol. The intermediate acyl-type radicals were in addition successfully exploited in stereoselective radical cyclisations. The hemiaminals derived from mono-reduction and cyclisation of barbituric acid derivatives have been exploited as N-acyliminium equivalents, affording hydrouracils with an excellent degree of regio- and stereoselectivity. Efforts towards the synthesis of the azulene framework of pseudolaric acid B using a model substrate are also described.

A field in bloom: photoredox catalysis has allowed chemists access to highly reactive intermediates via the photo-mediated excitation of transition metal complexes and organic dyes for the mild generation of free radicals. These complexes and dyes are designed based on Nature’s blueprints of light-harvesting biomolecules that transform solar energy (photons) into chemical energy during photosynthesis. Light-mediated chemical activation is regarded as one of the most sustainable forms of chemical activation being that the energy provided by the sun is considered renewable and largely underutilized and presents an attractive avenue for research and development of new transformations that are mild, efficient, and waste-limiting in organic synthesis. Radical chemistry and photochemistry are united in their inherent ability to undergo single (or photoinduced) electron transfers by one-electron reaction modes. Combining these unique fields, photoredox catalysis has emerged as a mild and efficient alternative to classic alkyl radical generation using hazardous initiators and organostannanes. Photoredox catalysis has been dominated by ruthenium- and iridium-based polypyridyl complexes. These complexes are limited by their inherent redox potentials, restricting their reactivity towards relatively activated bonds. Nonactivated bromoalkanes and arenes are considered challenging substrates to engage using redox chemistry and typically only accessible in the realm of organostannane chemistry. Described herein are the efforts towards the discovery of free radical based organic transformations derived from nonactivated bromoalkanes and arenes mediated by photochemical excitation of polynuclear gold(I) complexes as photoredox catalysts. This work represents some of the first uses of a photoredox catalyst in the reduction of substrates having such high reduction potentials and offers a practical and useful alternative to classic radical reactions mediated by initiators (peroxides, persulfates, and azo compounds) and toxic organostannanes (Bu3SnH). Using gold based photoredox catalysts, the research conducted has provided many methodological advancements for the mild and efficient formation of carbon-carbon bonds using nonactivated bromoalkanes and a large collection of radical acceptors. Establishing the use of these photoexcited polynuclear gold(I) complexes in the context of classic radical reactions in organic synthesis was important for their validation as useful photocatalysts. First, the Ueno-Stork cyclization of nonactivated bromoalkanes was used to demonstrate the powerful reducing capabilities of the excited-state gold(I) complexes. Next, a photo-mediated variant of the Appel reaction was described, where the transformation of an alcohol to a bromoalkane was achieved using carbontetrabromide and N,N-dimethylformamide through the intermediacy of a Vilsmeier-Haack reagent. In combination with the hydrodebromination chemistry developed with photoexcited polynuclear gold(I) complexes, a photo-mediated one-pot formal deoxygenation reaction of alcohols was described; a useful alternative to the organostannane mediated Barton-McCombie deoxygenation reaction. Finally, in the field of medicinal chemistry, the functionalization of heteroarenes is of high interest for the discovery of drug candidates and bioactive molecules. In this respect, one of the most useful reactions for the functionalization of heteroarenes by alkyl radicals is the Minisci reaction using silver salts, carboxylic acids, and persulfates. Detailed are the efforts for the development of a photo-mediated redox-neutral improvement of the Minisci reaction, needing only gold(I) photocatalyst and nonactivated bromoalkane in the presence of heteroarenes. Overall, the work described in this thesis represents the push for mild and efficient alternatives to the relatively harsh conditions and/or toxic reagents and byproducts associated with classic radical chemistry. These studies demonstrate the ability to control highly reactive alkyl radical intermediates with the goal of their broader application in synthetic organic chemistry. The use of photoexcited polynuclear gold(I) complexes as potent reductants compared to ruthenium- and iridium-based polypyridyl complexes is illustrated through the genesis of highly reactive alkyl radicals from nonactivated bromoalkanes.

Les objectifs de ce travail portent sur le rôle de l'oxydation de biocarburants lignocellulosiques dans la cinétique de formation des oxydes d'azote. Le choix s’est porté sur le furane (F) et le tétrahydrofurane (THF). Cette thèse a permis d’acquérir une base de données expérimentales détaillée afin de tester des mécanismes cinétiques d'oxydation de ces biocarburants disponibles dans la littérature ainsi que d’évaluer leur aptitude à prévoir la formation de CH initiateur du NO précoce. Six flammes laminaires prémélangées à basse pression (5.3 kPa) ont été étudiées à deux richesses (1,0 et 1,2). Trois combustibles ont été considérés: (i) le méthane pur utilisé comme référence, (ii) un mélange F (50%)/méthane (50%), et (iii) un mélange THF (50%)/méthane (50%) pour évaluer l'impact de ces biocarburants sur la formation de NO. Les profils de fraction molaire des espèces sont été déterminés par chromatographie en phase gaz couplée à des détecteurs FID/TCD/MS. Les profils de fraction molaire du NO et du radical CH ont été mesurés par Fluorescence Induite par Laser (LIF). Les résultats expérimentaux montrent que la différence de structure moléculaire de ces éthers cycliques induit des différences significatives dans la formation des espèces intermédiaires issues de leur oxydation. Ainsi, l'oxydation de F favorise la formation de CH et donc la production de NO par rapport aux flammes de méthane et de THF. Les profils expérimentaux ont été comparés aux profils simulés par deux modèles cinétiques, indiquant que ces mécanismes nécessitent d’être optimisés sur la formation de CH avant d’envisager l’introduction d’un sous-mécanisme relatif à la chimie de l’azote. / The objective of this work is to investigate the role of oxidation of lignocellulosic biofuels in the formation of nitrogen oxides (NOx) in flames. The biofuels chosen are furan (F) and tetrahydrofuran (THF). This thesis enabled to acquire a detailed experimental database in order to test the kinetic mechanisms available in literature of the oxidation of these biofuels as well as to evaluate their ability to predict the formation of CH, the key species on the prompt-NO mechanism. Six premixed low-pressure laminar flames (5.3 kPa) were studied under two equivalent ratio conditions (1,0 et 1,2). Three fuels are considered: (i) pure methane, which is used as a reference flame, (ii) a F (50%)/methane (50%) mixture, and (iii) THF (50%)/methane (50%) in order to evaluate the impact of these biofuels on NOx formation. The structure of these flames was characterized by establishing the mole fraction profiles of stable intermediates and products using gas chromatography coupled with FID/TCD/MS detectors. The mole fraction profiles of NO and CH radical were detected by Laser Induced Fluorescence (LIF). The experimental results show that the different molecular structures of these cyclic ethers leads to significant differences in the formation of intermediate species and pollutants. Thus, F oxidation promotes the CH formation and then the NO with respect to methane and THF. The experimental profiles were compared with the simulated profiles using two detailed kinetic models. The preliminary modeling study indicates that the studied mechanisms require some improvements on the prediction of CH formation before to consider the introduction of a sub-mechanism on nitrogen Chemistry.

Magíster en Gestión y Políticas Públicas / Erradicar la pobreza es el primero de los Objetivos para el Desarrollo Sostenible; un compromiso mundial en la Era de la Información hacia la Sociedad del Conocimiento. Entonces ¿pueden las Tecnologías de la Información y la Comunicación (TIC) jugar un rol central en la reducción global de pobreza como herramientas disruptivas de las políticas públicas? Para guiar y dan propósito a la investigación se generan, a partir de esta, otras cuestiones: ¿Qué experiencias internacionales existen en el uso de TIC para la reducción de pobreza? ¿Cuáles de ellas promueven la construcción de capital social? Y de estas últimas ¿qué elementos son relevantes desde el constructivismo para generar innovación pública? Con el objetivo general de Identificar elementos relevantes de experiencias internacionales de combate a la pobreza mediante el uso de TIC para sustentar propuestas de líneas generales de acción y gestión pública innovadoras en la construcción de capital social desde el enfoque constructivista radical se realiza este estudio hermeneútico cualitativo exploratorio que analiza 53 experiencias internacionales a partir del constructo Pobreza entendida como insuficiencia en el acceso a oportunidades y privación de capacidades básicas; Capital Social como recurso para el desarrollo del bienestar; TIC como herramientas de ampliación de capacidades; Innovación Pública como modelo de función estatal desde el cual proyectar propuestas y Constructivismo Radical como plataforma filosófica para la auto transformación ontológica mediante la conversación. Los resultados arrojan que el acceso a servicios de telecomunicaciones es la intervención de mayor incidencia, y la mejor según el ranking del estudio- es la formación de radios comunitarias combinadas con otras TIC como medios para el empoderamiento. Destacan las experiencias provenientes del sector social en la generación de capital social, particularmente las de Asia Meridional por su integralidad, y en especial la Community Media Trust de la Deccan Development Society por su perspectiva constructivista radical. La complejidad para identificar causalidad entre reducción de pobreza y uso de TIC motiva la discusión entre expertos y tomadores de decisiones, sin que por el momento sea posible establecer correlaciones positivas o negativas al respecto. Esta investigación propone trascender causalidad para enfocarse en el potencial de las TIC mixtas con base en la radio comunitaria para reducir pobreza; prefiriendo el uso de la voz y la imagen como vías expresivas; priorizando colectivos (reales o virtuales) sobre individuos; incorporando dinámicas exitosas del sector social a las políticas públicas; anteponiendo desarrollo de habilidades socio-emocionales a cognitivas y privilegiando proyectos con perspectiva de género. Lo anterior en un marco de estrategias experimentales con uso de tecnologías sociales participativas incluida la gestión de saberes locales- y procesos iterativos que desde el constructivismo radical amplifiquen capacidades expandiendo conciencias; empoderen transformando ontológicamente, y habiliten a la auto-innovación personal y colectiva, generando autonomías para el bienestar. / Esta tesis forma parte del programa de becas de cooperación horizontal reciprocidad Chile-México de la Agencia de Cooperación Internacional de Chile (AGCI)

Abstract: Styrene and methyl methacrylate have been polymerized successfully through atom transfer radical polymerization (ATRP) in aqueous dispersed media (emulsion ATRP). The thesis is divided into four experimental parts. In the first part, a water-soluble initiator was prepared for emulsion ATRP and utilized under various conditions in the presence of two ligands N, N, N’, N’’, N’’-Pentamethyldiethylenetriamine and 2,2’-bipyridine to attain activation/deactivation only in the oil phase with Tween 20 as a non-ionic surfactant. The initiator was synthesized by the reaction of diethanolamine with α-Bromoisobutyryl bromide in anhydrous tetrahydrofuran. 1H NMR spectroscopy (500 MHz, deuterium oxide, or chloroform-d) was performed to confirm the successful synthesis of the initiator and polystyrenes. In the second and third parts, two commercial initiators were used, poly(ethylene glycol) methyl ether 2-bromoisobutyrate (Mn= 2000 g/mol), and 2-hydroxyethyl 2-bromoisobutyrate (Mn= 211.05 g/mol). BPY, tris(2-pyridylmethyl) amine and 4, 4’-dinonyl -2, 2’-dipyridyl were used as the ligands with various molar ratios. Polyoxyethylene (80) sorbitan monooleate, and polyoxyethylene (20) oleyl ether were used as non-ionic surfactants. In the fourth part, a macroinitiator was synthesized by the reaction of polyoxyethylene (20) stearyl ether with α-Bromoisobutyryl bromide. The formation of the macroinitiator as well as the successful synthesis of poly(ethylene glycol)-b-polystyrene, and poly(ethylene glycol)-b-poly(methyl methacrylate) block copolymers were confirmed by Fourier transform infrared and 1H NMR spectroscopies. The molecular weight of the resulting polymers, as well as the stability of the emulsion systems, were evaluated by gel permeation chromatography and dynamic light scattering, respectively.