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Contre la raison? : l'opposition au rationalisme dans le discours de l'écologisme fondamentalisteFontaine, Mathieu January 2006 (has links) (PDF)
Le but du présent mémoire se divise essentiellement en deux objectifs. Le premier de ceux-ci consiste à repérer, dans le discours de l'écologisme fondamentaliste, l'opposition au rationalisme moderne. Ce premier objectif est cependant secondaire puisque son utilité réside dans l'atteinte du second objectif. Ce dernier consiste effectivement, quant à lui, à établir une critique de cette opposition qui aura été rendue manifeste au lecteur avec l'atteinte du premier objectif. Nous nous limiterons, pour ce faire, à employer les grilles d'analyse du rationalisme fournies par des auteurs du courant écologiste fondamentaliste afin de les confronter à celles fournies par des auteurs qui se penchent plutôt directement sur la critique du rationalisme, c'est-à-dire qui n'ont pas l'écologisme comme point de départ. Le lecteur comprendra que le travail qui suit s'appuie sur une démarche analytique pour parvenir à son but. Quatre sujets généraux sont abordés par cette démarche : la critique du rationalisme, les impacts environnementaux du rationalisme selon le discours écologiste fondamentaliste, la légitimation rationnelle à l'intérieur du discours écologiste fondamentaliste et le recours à la pensée mythique dans le discours écologiste fondamentaliste. L'hypothèse principale de ce mémoire est que l'opposition au rationalisme dans l'écologisme fondamentaliste ne tient pas la route puisque ce discours s'appuie essentiellement sur une approche rationaliste de la réalité, même dans ses exemples les plus radicaux.
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Synthetic Studies of PyrrolophenanthridinesChen, Xie-ying 12 June 2006 (has links)
The pyrrolophenanthridine class of alkaloids which have been isolated from various species of Amaryllidaceae.In intramolecular radicalcyclization, we used three methods to synthesize pyrrolophenanthridine.
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A New Approach to Indolizidine Skeleton (1)Formal Synthesis of Dendroprimine (2)Synthetic Study Toward IpalbidineCheng, Li-Ming 06 July 2001 (has links)
none
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Studies on Lewis acid-promoted radical cyclization reactions /Gu, Shen. January 2002 (has links)
Thesis (Ph. D.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 168-177).
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Mechanistic Studies of Radical-mediated Polyolefin ModificationsWu, WEI 12 January 2009 (has links)
The free radical addition of saturated polymers and small molecules to unsaturated monomers is used to prepare functional derivatives under solvent-free, reactive extrusion conditions. Of particular interest are the dynamics and yields of conventional peroxide-initiated grafting of vinyltrialkoxysilanes to polyethylene, as well as the mechanisms through which bicumene initiates the process at high temperatures. Knowledge of these commercial processes is applied toward the development of new graft modification technology, including radical initiated polymer addition to alkynes, and a new variation of precipitation polymerization chemistry.
The thermolysis of bicumene at temperatures ranging from 220°C to 270°C was used to initiate C-H bond addition from alkanes to vinylsilanes in a high-temperature analogue of conventional grafting practice. The initiation mechanism is shown to involve direct hydrogen atom abstraction by intermediate cumyl radicals, as well as autooxidation processes involving cumyl radicals and available oxygen.
Conventional peroxide initiated graft modifications of polyethylene with vinylsilanes are examined from the standpoint of reaction dynamics and yields. The influence of peroxide loading and monomer concentration on these reaction variables can be described using a simple quasi-steady state kinetic analysis, while the unusual insensitivity of reaction yields to temperature requires further investigation.
A new chemical modification of saturated polymers involving free radical addition to mono-substituted alkynes is presented and examined in terms of reaction yield, graft structure, and changes to molecular weight. Model compounds are used to characterize alkyne grafting products, and to probe the relationship between reagent properties, reaction yields, and product structures.
The discovery of cross-linked particles in the products of polypropylene graft modifications with triallyltrimesate has led to a variation of precipitation polymerization wherein C-H bond addition to an allyl monomer contributes to molecular weight growth, thereby incorporating a significant amount of saturated hydrocarbon into the solid phase. The relationships between reaction conditions and solid-phase composition and morphology are discussed. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2008-12-18 14:35:52.483
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TOWARDS WATER-SOLUBLE PEROXYL RADICAL CLOCKSDhanoa, Jassimranjeet 01 June 2010 (has links)
Peroxyesters undergo homolytic O-O bond cleavage under thermal and photolytic conditions, forming an alkoxyl and acyloxyl radical, the latter of which rapidly decarboxylates to form a carbon centered radical. While peroxyesters are generally decomposed under anaerobic conditions to serve as sources of carbon-centered radicals to initiate radical reactions, it has been shown that β,γ-unsaturated peroxyesters can decompose to yield a delocalized carbon-centered radical which can serve as a precursor to a powerful peroxyl radical clock. This competitive kinetic approach is attractive as it allows the facile determination of rate constants for formal H-atom reactions between peroxyl radicals and reductants (e.g. phenolic and aromatic amine antioxidants) without the need for specialized equipment. Furthermore, this approach allows for the determination of this kinetic data in a wide variety of solvents.
Herein, we present our work towards the development of a water-soluble peroxyl radical clock, such that the kinetics of reactions of peroxyl radicals with water-soluble reductants can be determined. To do so, we have designed β,γ-unsaturated peroxyesters analogous to those we have previously developed, but that bear either carboxylate or poly(ethylene glycol) moieties to improve solubility in aqueous media. In addition, we have carried out a preliminary investigation of the use of alkyl and acyl xanthates as precursors to peroxyl radical clocks. These radical precursors offer the advantage that they have a pronounced ultraviolet absorption that tails into the visible, permitting efficient photochemical generation of the same alkyl radicals, but at longer wavelengths than that which are currently employed. / Thesis (Master, Chemistry) -- Queen's University, 2010-05-31 09:53:50.676
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Formal radical cyclization onto aromatic rings, cascade intramolecular conjugate displacement and synthetic studies on marinopyrrolesChen, Zhenhua Unknown Date
No description available.
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Carbon-carbon bond formation mediated by phosphorous-centred radicalsGraham, Stephen R. January 2000 (has links)
No description available.
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Exploration of redox processes in radical chemistryHassani, Mourad January 2003 (has links)
No description available.
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Toward Development of Radical Materials for Charge Storage: Synthesis and Electrochemistry of Benzotriazinyl Radical DerivativesOakley, Nicholas Alfred 27 September 2013 (has links)
The benzotriazinyl radical is a highly stable organic radical that is known to
possess fast and reversible oxidation and reduction electrochemical processes. Such
properties make it an ideal candidate for use as an anodic or cathodic charge storage
material in a new class of high-power secondary batteries known as organic radical
batteries. Towards this application, several new benzotriazinyl radical derivatives were
synthesized and fully characterized using electronic absorption, EPR, and IR
spectroscopy as well as elemental analysis and mass spectrometry. The electrochemical
properties of the radicals were studied using cyclic voltammetry.
The introduction of electron donating groups onto the structure of the radical was
found to result in cathodic shifts in both of the electrochemical processes, without loss of
reversibility. It was also found that in some cases functional groups led to the
destabilization of the radical to a known chemical oxidation pathway that resulted in the
formation of closed-shell iminoquinone compounds. These materials demonstrated good
multi-electron accepting properties, undergoing two reversible one-electron reduction
processes.
Synthetic methodologies were developed for the preparation of two new classes
of benzotriazinyl biradicals. One class used an expansion of a known benzotriazinyl
radical synthesis to prepare a m-phenylene-bridged biradical, while the other class used
microwave-assisted synthesis to prepare biradicals bridged by electron accepting
aromatic diimides. Spectroscopic studies of both classes of biradical showed electronic
isolation of the two radicals within each molecule, consistent with computational
predictions. This resulted in minimal perturbation of the electrochemistry of these
compounds from that of typical benzotriazinyl radicals.
The solid state properties of a selection of benzotriazinyl radical derivatives were
studied. Structural information obtained through single crystal X-ray diffraction studies
showed significant intermolecular π-π and hydrogen bonding interactions. These solid
state interactions were found to provide pathways for magnetic exchange, as determined
using SQUID magnetometry. Additionally, preliminary conductivity studies indicated
semiconducting behaviour in the compounds that were studied, warranting further
studies.
Anionic polymerization of a vinyl-functionalized benzotriazinyl radical was
investigated as a method for the synthesis of a pendant benzotriazinyl polyradical with a
saturated backbone. The electrochemistry of the putative polymer was identical to the
monomer, maintaining reversibility of both the oxidation and reduction processes and
verifying that the polymer could be used as an anodic or cathodic charge storage material.
SQUID magnetometry was used to estimate a polymer spin content to be ~ 44 %. / Graduate / 0485
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