No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

and biological sources. Recent advances in decarboxylative activation has allowed for the application of these reagents as building-blocks in organic synthesis; presenting viable, green alternatives to traditional organometallic or organohalide reagents. This thesis focuses on the development of novel transition metal catalysed decarboxylations, and investigation into the mechanisms of these, and related transformations. In the first part of the thesis, an extensive overview of the latest Carboxylic acids are cheap, shelf-stable reagents readily available from several commercial and biological sources. Recent advances in decarboxylative activation has allowed for the application of these reagents as building-blocks in organic synthesis; presenting viable, green alternatives to traditional organometallic or organohalide reagents. This thesis focuses on the development of novel transition metal catalysed decarboxylations, and investigation into the mechanisms of these, and related transformations. In the first part of the thesis, an extensive overview of the latest decarboxylative methodologies is presented, with discussion of the mechanistic aspects of different metal-catalysed decarboxylations. This is followed by a mechanistic investigation into the silver-catalysed decarboxylation of benzoic acids. In this system, an ortho substituent is required to facilitate decarboxylation. Using DFT, kinetic studies and the Fujita-Nishioka LFER we were able to show that the ortho-effect is a combination of electronic and steric effects, contrary to previous reports. In the second part of the thesis a practical, mild and highly selective protocol for the mono-deuteration of a variety of (hetero)arenes is described. Ag-catalysis was shown to facilitate the deuterodecarboxylation of (hetero)aromatic carboxylic acids in D2O/DMSO. The last two parts of this thesis focus on the formation and activation of carbon-fluorine bonds. Organofluorine compounds are of great importance to the agrochemical and pharmaceutical industries; however, there are limited examples of selective C-F bond formation that do not require stoichiometric metals, harsh conditions or toxic reagents. Using transition metal catalysis, we investigated a fluorodecarboxylation methodology. Initially this was explored in aromatic systems; though no synthetically useful yields were realised. However, aliphatic carboxylic acids were successfully transformed under aqueous conditions. The developed protocol was exploited to access benzylic fluorides. Subsequently, we established unprecedented metal-free conditions to activate their C-F bonds towards nucleophilic displacement; presenting a novel, decarboxylative methodology to furnish carbon-carbon and carbon-heteroatom bonds.

A study has been conducted on the aeration of reduced ilmenite with emphasis on increasing the aeration speed and understanding the mechanism of the aeration based on laboratory scale experiments. These issues were highlighted by comparing the currently operating Becher process which incorporates the use of an ammonium chloride catalyst in the aeration process.The speed of production of synthetic rutile from the Becher process is currently dictated by the time the reduced ilmenite remains in the aeration tank. As these times can vary greatly for no obvious reason, experiments were conducted to find which parameters could be changed to increase the speed of leaching. It was found that by increasing the oxygen content to 100 per cent the aeration time was reduced by at least half.By replacing ammonium chloride with various other amine compounds as the catalyst it was found there was a relationship between pK[subscript]a and aeration time. It was also found that the more sterically hindered the amine group, the slower the leaching. The use of ethylenediammonium chloride has shown that, when used at two thirds of the ammonium chloride concentration, aeration can be completed an hour (17%) faster than with the ammonium chloride catalyst. Furthermore, when ethylenediammonium chloride was used with a 100 per cent oxygen gas flow the aeration time was reduced by two thirds.Other compounds that did not contain amine groups were also investigated as catalysts in reduced ilmenite aerations. Of those tested only a citric acid / trisodium citrate mixture managed to aerate the reduced ilmenite substantially faster than the standard ammonium chloride catalyst. Other compounds with similar structure to the citrate ion failed to aid the aeration at all.

No description available.

No description available.