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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Synthetic efforts towards new stable free radicals

McKinnon, Stephen David James 10 April 2008 (has links)
A series of new 1,5-dimethyl-6-0x0-verdazyl radicals were prepared bearing either a hydroquinone or the 3,5-di-tertiary-butyl phenol substituent in the 3 position of the verdazyl ring as precursors to verdazyl 1 semiquinone diradical anions or verdazyl 1 phenoxyl diradicals. All radical precursor tetrazanes were characterized by 'H / 13c NMR and FTIR spectroscopies, MS, and elemental analysis. Oxidation of the tetrazane precursors with NaI04 or A ~ + gave verdazyl radicals as microcrystalline solids. All verdazyl radicals were characterized by EPR, UV-visible, and FTIR spectroscopies, and high-resolution MS or elemental analysis. All attempts to oxidize the hydroquinone or phenol moieties were unsuccessful as was coordination chemistry with those verdazyls bearing a chelating ortho-hydroquinone. Several molecules were synthesized as building blocks towards tris(2,6- disubstituted-4-pyridy1)methyl radicals where the substituents were ether chloro- or methoxy- groups. All of these building blocks (aldehydes, ester, alcohol, and ketone) were characterized by 'H / 13c NMR and FTIR spectroscopies, MS, and elemental analysis. All attempts to insert a third ring onto bis(2,6-dichloro-4-pyridy1)ketone to give the radical precursor triarylmethanol have been unsuccessful. Supervisor: Dr. R. G. Hicks (Department of Chemistry)
2

Electronic spectroscopy of the alkoxy radicals

Gopalakrishnan, Sandhya, January 2003 (has links)
Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xxiv, 173 p.: ill. (some co.). Includes abstract and vita. Advisor: Terry A. Miller, Dept. of Chemistry. Includes bibliographical references (p. 171-173).
3

Pharmacokinetics and metabolism of the reactive oxygen scavenger, [alpha]-phenyl-N-tert-butyl nitrone (PBN) and the effects of 3-nitropropionic acid in the Sprague-Dawley rat /

Trudeau-Lame, Mary E. January 2002 (has links)
Thesis (M.S.)--Central Connecticut State University, 2002. / Thesis advisor: Michael A. La Fontaine. " ... in partial fulfillment of the requirements for the degree of Master in Natural Science-Chemistry." Includes bibliographical references (leaves 61-66). Also available via the World Wide Web.
4

The study of free radicals produced by photochemical means

Porter, George January 1949 (has links)
No description available.
5

Free radical methodology and approaches to the synthesis of roseophilin

Burrows, Jeremy N. January 1996 (has links)
The homolytic Brook rearrangement is discussed and homolytic fragmentations of epoxides and epoxysilane chemistry are reviewed. Thiyl radical induced isomerisation was performed on spiro alkenylepoxysilanes to generate novel alkenyl-α-trimethylsilylaldehydes rather than the products of radical Brook rearrangement. The trimethylsilylaldehydes were shown to isomerise on heating to silyldienol ethers and, via the addition of a Grignard reagent, to act as stereoselective vinyl cation equivalents. Attempts to extend the scope of the isomerisation to non-rigid systems met with failure. A review of the antibiotic Roseophilin is presented. Cycloaddition-fragmentation approaches to medium and large rings are reviewed as a prelude to our first route, the proposed Michael addition-retro-aldol fragmentation of the Diels-Alder adduct derived from isopropyl-cyclopentadiene and cyclodec- 2-yn-1-one. The novel ynone, synthesised via the intramolecular Friedel-Crafts acylation of 10-trimethylsilyl-9-decynoyl chloride, was found to isomerise readily to bicyclo[4.4.0]dec-1(6)-en-2-one therefore the model Diels-Alder reaction with cyclopentadiene was effected in one-pot from the cyclisation precursor. Details of the attempted fragmentation of tricyclo[10.2.1.0<sup>2,11</sup>]pentadeca-2(11),13-dien-3-one are then described but, due to inconclusive results, an alternative study was instigated. The use of free-radical macrocyclisations in the synthesis of large rings is reviewed with particular reference to the synthesis of natural products. Three strategies for the formation of a bicyclo[10.2.1]pentadecanone skeleton are reported, and subsequent model studies described. Cuprate additions to vinyl lactones and epoxides are discussed. The preferred strategy, involving a cycloalkyl tether between the radical donor and radical acceptor groups, was extended to a system which was derived from the addition of various cuprates to 2-oxabicyclo[3.3.0]oct-7-en-3-one The preparation of cuprates derived directly from 6-iodohexan-1-ol and 1-chloro-6-iodohexane is described. The trans- cuprate addition products were converted successfully to bicyclo[10.2.1]pentadec-12-en-3-one, and the cis- analogues, accessible through a novel regio- and stereoselective hydroboration-fragmentation reaction of 7- (6'-chlorohexyl)-2-oxabicyclo[3.3.0]oct-7-en-3-one, led to bicyclo[10.2.1]pentadec- 13-en-3-one. The successful cyclisations of model oximes, to form nitrones having the correct connectivity for the third ring of Roseophilin, are described. Cuprate additions to 6-(1'-methylethyl)-2-oxabicyclo[3.3.0]oct-7-en-3-one resulted in anti- attack; the cis- adducts were inaccessible via the above methodology but a few intermediates in the trans- series were prepared. Future routes and modifications to the methods developed are then discussed.
6

Determination of the philicity of the aryl radical

Kirsop, Peter James January 2007 (has links)
Radicals, like other functional groups, may be classed as nucleophiles or electrophiles depending upon their character. Much has been done in the past to determine the· nucleophilicity or electrophilicity of a wide ra~ge of radicals, but it .. does not appear that the philicity ofthe aryl radical has yet been determined. A competitive cyclisation of an aryl radical to one of two alkyl chains containing olefins ofdiffering electron density was undertaken to determine aryl radical philicity. Prior to cyclisation, synthesis of the precursors was required, starting from simple commercially available aromatic compounds. A wide range of allyloxy aromatic compounds with different substituents on the two olefins was synthesised. In the course of the required multi-step synthesis many previously unreported compounds were isolated and fully characterised, including crystal X-ray diffraction studies where crystals were obtained. To investigate the effects of different electron density in the aryl ring a further range of competitive cyclisation precursors were synthesised with an ester group para to the site where the aryl radical is formed. Studies into the synthesis of a competitive cyclisation precursor with olefin bearing side chains with no heteroatom were also undertaken. The procedure for the cyclisation reactions and subsequent work-up was optimised under both conventional and microwave methodology. Analysis of the products was performed using both quantitative and qualitative analytical techniques. Quantitative analysis was performed using gas chromatography, IH NMR spectroscopy with an internal standard and isolation of products. Qualitative analysis was performed using both ID and 2D NMR spectroscopy. Analysis of the results of the competitive cyclisation reactions show beyond reasonable doubt that the aryl radical is nucleophilic in character.
7

Free radicals in biological processes

Thornalley, Paul J. January 1982 (has links)
No description available.
8

Intramolecular rearrangements of amides and peroxides

Acott, Brenton. January 1966 (has links) (PDF)
[Typescript] Includes bibliography. Decomposition of alkyl hydroperoxides and peracetates -- Photolysis of N-chloro-amides: a. Reactions of primary amido radicals; b. Reactions of N-alkylacetamido radicals -- Reactions of lead tetra-acetate with primary amides: a. Scope; b. Mechanism -- Decomposition of alkyl hydroperoxides and peracetates -- Photolysis of N-chloro-amides -- Reactions of lead tetra-acetate with primary amides.
9

Polymerization and characterization of poly(ethyl methacrylate)

Bakioğlu, Levent. January 2003 (has links) (PDF)
Thesis (M.S.)--Middle East Technical University, 2003. / Keywords: Ethyl methacrylate, atom transfer radical polymerization, gamma irradiation, free radical polymerization, viscosity.
10

Intramolecular rearrangements of amides and peroxides / by Brenton Acott.

Acott, Brenton January 1966 (has links)
[Typescript] / Includes bibliography. / 178 leaves ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Organic Chemistry, 1966

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