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Photocatalysis for organic synthesis

A wide range of commercially available self-cleaning materials/products are now available, from architectural materials, such as; glass, paint, plastics, and concrete, to water and air purification systems. These products exploit the destructive oxidative nature of SPC to purify air and water. In contrast, this thesis introduces the less well studied use of SPC to mediate the synthesis of a range of useful organic species, and aims to develop a fast screening process for monitoring such reactions to aid future developments in SPC mediated organic synthesis. It is demonstrated that NMR is a very effective way to monitor SPC mediated organic reactions. By coating the inside of an NMR tube with a sol-gel titania film, and performing SPC reactions in-situ, inside a sealed NMR tube on a 1 mL scale, the need for sample-taking and pre-treatment is negated. The small scale also allows for much faster reaction times. For example, it is shown for the SPC oxidation of toluene, that the use of this NMR/sol-gel titania method is ca. 10 times faster than the more conventional large scale (100 mL) reaction utilising a titania dispersion, whilst still providing similar product yields, thus, demonstrating a new rapid screening method for SPC mediated organic synthesis reactions. Using the new fast screening NMR tube method, the SPC C-C coupling of phenoxyacetic acid (PAA) with N-methylmaleimide (NMI) to produce adduct and cyclic products in yields up to 67% and 15% respectively after only 15 min of UVA irradiation was assessed in detail. Despite the well-known photochemical feature of NMI to form dimers efficiently, the background photochemistry and photocatalysis associated with the individual reactants are shown to be minimal due to the faster SPC kinetics for the coupling reaction. Acrylamide (ACM) was also used in the SPC C-C coupling with PAA, gaving rise to only one product, 4-phenoxybutanamide, in high yields (78%). This efficient reaction was then used to assess the robustness and reusability of the titania coated NMR tubes.

Identiferoai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:675420
Date January 2014
CreatorsO'Rourke, Christopher
PublisherQueen's University Belfast
Source SetsEthos UK
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation

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