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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

Novel fluorocarbon iodides

Copin, Elodie January 2002 (has links)
This work describes the three-step synthesis of some new fluorocarbon iodides. First, functionalisations of carbon-hydrogen bonds, using fluorinated alkenes via a free radical chain mechanism, were carried out. The HFP-adducts were then further functionalised by elimination of hydrogen fluoride to yield a series of fluoroalkenes, which were then converted to fluorocarbon iodides by means of a mixture of IF(_5)/I(_2) (corresponding to iodine monofluoride formed in situ). Chemistry of the new fluorocarbon iodides was investigated, especially in reactions with thiols.
2

Polyfluorinated compounds via free-radical reactions of alcohols and diols

Farren, Christopher January 1998 (has links)
Site-selective incorporation of fluorocarbon substituents into organic molecules is a field of continuing interest, and a variety of approaches have been reported. The research described within this thesis is concerned with the functionalisation of C-H bonds adjacent to primary or secondary hydroxyl units via free-radical additions to fluoroalkenes. A range of cyclic and acyclic alcohols and diols have been functionalised in this manner, and both substituent and electronic effects on the radical process have been investigated. Further functionalisation of the polyfluoroalkylated products has been performed, giving a range of new fluorinated systems, and an investigation into the chemistry of these systems has begun.
3

Reactions of Manganese Hydrides with Amine-Boranes and Fluoroalkenes

Barnawi, Bakr 31 August 2021 (has links)
Organofluorine compounds find various applications ranging from pharmaceuticals to refrigerants, insecticides, high-value fluoropolymers and reagents in catalysis. However, the synthesis of organofluorine compounds depends on toxic chemicals such as hydrogen fluoride, chlorinated hydrocarbons, reactive F2 gas and environmentally persistent long-chain fluorosurfactants. Recently more sustainable, energy-efficient syntheses have been developed using base metal-catalyzed transformations of fluoroalkenes and the formation and functionalization of d6-8 fluorometallacycles. In this thesis, we use manganese complex precursors to prepare the first examples of d4 fluorometallacycles. Work in Chapter 2 describes the synthesis and one-electron reduction of manganese bis(diphosphine)- and tetrakis(phosphite) dibromide complexes, MnBr2(P-P)2 and MnBr2[P(O-i-Pr)3]4 and reactions of the corresponding reduced Mn(I)Br complexes with tetrafluoroethylene (TFE). Products proposed to be d4 perfluorometallacycles, MnBr[-CF2(CF2)2CF2-](P-P) proved to be unstable, reforming TFE upon application of vacuum. In Chapter 3 we show that photolysis of ligated manganese(I) carbonyl bromide complexes, MnBrLn(CO)5-n, in the presence of TFE, chlorotrifluoroethylene (CTFE) or perfluoro(methyl vinyl ether) (PMVE) in tetrahydrofuran affords the Mn-H insertion products, Mn(CF2CFXH)(L2)(CO)3 (X = F, Cl, OCF3) only for L2 = DPPE [1,2-bis(diphenylphosphino)ethane] as well as a solid by-product proposed to be MnBr2Ln. These reactions are accompanied by THF fluoroalkylation products, O[-(CH2)3CH(CF2CFHX)-]. By switching to methyl t-butyl ether solvent, we showed that exhaustive photolysis of MnBr(CO)5 + 3 equiv. of DPPE gave a new product proposed to be the first stable d4 fluorometallacycle, MnBr[-(CF2)4-](CO)(DPPE). Reactions of the fluoroalkenes with zerovalent Mn2(CO)10 also contributed to our understanding of potential reaction pathways to form these Mn-H-derived products. Previous work in the Baker group compared FeH2(dmpe)2 and [FeH(H2)(dmpe)2]+ as catalysts for the dehydrogenation of amine-boranes [dmpe = 1,2-bis(dimethylphosphino)ethane]. In Chapter 4 the catalytic reactivity and selectivity of MnH(H2)(dmpe)2 are compared with those observed using the Fe analogs and the catalyst resting state, Mn(2-BH4)(dmpe)2, is identified. Finally, in Chapter 5 we summarize the findings of this thesis and suggests future directions based on this work.
4

Utilisation d'alcènes fluorés pour la synthèse et la fonctionnalisation de dérivés (hétéro)aromatiques et de composés phosphorés / Synthesis and functionalisation of (hetero)arenes and phosphorus containing compounds

Rousee, Kevin 07 February 2017 (has links)
Les fluoroalcènes, du fait de leurs propriétés physico-chimiques singulières, sont des composés intéressants présents dans de nombreux domaines comme les matériaux polymères, l'agrochimie ou encore la chimie médicinale. Les mono-fluoroalcènes présentent des similarités électroniques et géométriques avec la liaison amide et sont donc de très bons mimes de la liaison peptidique. Néanmoins, la synthèse et la fonctionnalisation de ces composés représente toujours à l'heure actuelle un enjeu synthétique important. Au cours de cette thèse deux briques moléculaires ont été préparées pour développer de nouvelles méthodes d'accès aux fluoroalcènes : les gem-bromofluoroalcènes et les α-fluoroacrylates. Les gem-bromofluoroalcènes ont été employés dans deux méthodologies. La première consiste en une mono-catalyse au cuivre pour réaliser la fluoroalcénylation d'hétéroraryles par fonctionnalisation catalytique de la liaison C-H de dérivés de type azoles. La seconde consiste en la phosphination des gem-bromofluoroalcènes par des phosphines boranes, dans le but d'obtenir de nouvelles phosphines originales. Les α-fluoroacrylates et les acides α-fluoroacryliques ont été utilisés dans deux réactions complémentaires. Une réaction de Heck a été employée pour synthétiser des α-fluoroacrylates tri- et tétrasubstitués, offrant une nouvelle voie d'accès à ces composés. Quant aux acides α-fluoroacryliques, ils ont été utilisés dans une méthode innovante de couplage décarboxylant/déshydrogénant avec des azoles. En effet, il s'agit du premier exemple de couplage décarboxylant/déshydrogénant sur des alcènes. / The fluoroalkenes are compounds with relevant physico-chemical properties and are used in various fields as polymers, agrochemistry or medicinal chemistry. Mono-fluoroalkenes can be used as an effective peptidic bond mimic because of their electronic and geometric similarity with the amide bond. Nevertheless, this interesting moiety still suffers from difficulty of synthesis which constitute a synthetic challenge. For that purpose, two build-blocks (gem-bromofluoroalkenes and α-fluoroacrylates) were used during this thesis to develop new access to mono-fluoroalkenes.The first one is the gem-bromofluoroalkenes moiety were used for the development of two methodologies. First, a copper-catalysed fluoroalkenylation via C-H bond functionalisation of heteroaryles has been reported. Then, the second methodology is the phosphination of gem-bromofluoroalkenes using phosphines boranes, in the goal to get new kind of phosphines.The second building-blocks used are the α-fluoroacrylates and α-fluoroacrylic acids which have been involved in two complementary reactions. A Heck reaction allowed the synthesis of tri- and tetrasubstitued α-fluoroacrylates, giving a new access to these compounds. α-Fluoroacrylic acids were used in a decarboxylative/deshydrogenative cross-coupling with azoles. Indeed, it is the first example of decarboxylative/deshydrogenative cross-coupling with alkenes.
5

High temperature materials from Bis-ortho-diynylarene (BODA)-derived resins and Perfluorocyclobutyl (PFCB) aryl ether polymers

Borrego, Ernesto Isaac 08 August 2023 (has links) (PDF)
This work expands the current understanding of materials chemistry and engineering capabilities of two synthetic platforms: 1.) bis-ortho-diynylarenes (BODA) and 2.) trifluorovinylaryl ethers (TFVE). Each platform possesses a unique chemistry which paradoxically enables the development of high-performance materials therefrom while simultaneously retaining exceptional melt and solution processability. Leveraging the apparent dichotomy in properties (performance/processability) obtainable from these two synthetics platforms, we have pursued and achieved a practical approach to high-temperature resistant materials with an immense potential for technology transfer and commercialization: 1.) BODA-derived resins (BDR) constitute a versatile platform of melt-processable resins capable of rapidly producing high performance matrix composites which include thermoset, carbon-carbon, and other specialty carbon or hybrid ceramic composite structure. BODA monomers can be synthesized via a three-step process from commercially available bisphenols and undergo a facile catalyst-free, thermal-initiated polymerization to yield polyarylene thermosets with outstanding thermal-oxidative stability, low heat release, flame resistance, and high carbon yields (>80%). The combination of melt processability, ease of cure, and high carbon yields in BDR provides an attractive quick, single-step fabrication of carbon/carbon (C/C) composites with excellent interlaminar shear strength (ILSS; ~1800 psi) after a single infusion/carbonization. Furthermore, our work in this area has shown that C/C from BDR can be prepared via a fast carbonization (10 °C/min), relative to typical 1 °C/min or 1 °C/hr industrial carbonizations, without causing undesirable shrinkage, cracking, interlaminar debonding, or detrimental changes in ILSS. 2.) Large polyaromatic hydrocarbons (PAHs) are typically known for their interesting thermal- and photo-optical properties but suffer from poor solubility and processability issues. Functionalization of these moieties with TFVE fluorocarbon groups enables melt or solution polymerization via a thermally initiated [2+2] cyclodimerization of the TFVEs towards high performance perfluorocyclobutyl (PFCB) aryl ether polymers. For example, successful fabrication of free-standing photoluminescent films with record high glass transition temperatures (Tg ~ 300 °C), exceptional thermal-oxidative stability (~250 °C, 24 h), unprecendented photostability at 250 °C in air, and excellent solubility in common organic solvents (at room temperature) have been realized via a set of triphenylene-enchained PFCB aryl ether polymers.

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