Fluorinated compounds are extremely desirable in several fields of the chemical industry, such as pharmaceuticals, materials and agrochemicals. Consequently, the development of novel methods of fluorination represents a major challenge in contemporary chemistry. Although several breakthroughs have been achieved in this area in recent years, the development of an active, stable, reusable and truly heterogeneous catalyst, able to perform selective C(sp3)-F formation, has not yet been achieved. Accordingly, this thesis explores the applicability of heterogeneous catalysts, to perform novel and selective C(sp3)-F bond formations. Different strategies to achieve C(sp3)-F bond synthesis were explored, including: i) fluorination of preactivated substrates (e.g. carboxylic acids), and ii) direct C(sp3)-H fluorination. Firstly, the applicability of heterogeneous materials, such as AgxO/TiO2 and pure TiO2, were investigated for decarboxylative fluorination reactions (R-COOH → R-F), with (photofluorination) and without the employment of light sources. Following an investigation of the catalytic performances of AgxO/TiO2 and pure TiO2 for fluorination of pre-activated substrates, an alternative route, whereby the applicability of heterogeneous materials for direct C(sp3)-H fluorination, was explored. Although more elegant and desirable, direct C(sp3)-H fluorination represents an immense challenge, mainly due to the scarce substrate reactivity, which typically results in a requirement of harsher reaction conditions. Due to the challenges associated with activation of C(sp3)-H bonds, two different systems to achieve direct C(sp3)-H fluorination were investigated. Firstly, the viability of benzylic fluorinations was explored, as these substrates represent excellent model substrates with slightly activated C-H bonds. Secondly, substrates possessing less active C(sp3)-H bonds, such as cyclooctane, were investigated for direct alkane fluorination.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:742879 |
| Date | January 2018 |
| Creators | Tarantino, Giulia |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/111540/ |
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