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.

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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Thesis (Ph. D.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 168-177).

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

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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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