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Title: Hydrogenation of ketones over platinum group metals : a DFT study
Author: Jeffery, Edward
ISNI:       0000 0004 2750 3580
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2007
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The enantioselective hydrogenation of a-ketoesters over a platinum surface modified by cinchona alkaloids has been studied using accurate computational modelling. A series of small prototype compounds were used to interact with the metal surface, leading to the study of acetone adsorption on a platinum surface. It was found that the enol and enolate isomers of acetone may play a crucial role in the surface chemistry. The enol form of acetone was significantly more stable than the keto-form, and the enolate form was also more stable. Vibrational frequency analysis suggests that the enolate form may prove to be a better fit to some of the experimental data than the commonly-accepted ketone form. The interaction of an a-ketoester, methyl pyruvate, with a platinum surface was then studied using the same techniques. The enol form was again the most stable surface species compared to the enolate and ketone forms. Additionally, the cis form of methyl pyruvate was generally more stable than the trans form. A full vibrational analysis was performed, allowing comparison with future experimental work. In order to investigate the conversion between the different types of isomer, an eigenvector following scheme is under development to find reaction barriers and transition states. To date, this has been applied to simpler systems with success and is in the process of being extended to more complicated applications. Concurrently, a technique to study the whole enantioselective reaction system was also being developed. This involves a modified simple QM/MM scheme containing a model for the surface, the substrate and modifier. This was successfully applied to a simple system (methyl pyruvate interacting with the surface and modifier) and yielded predicted ees in agreement with experimental observation. This was extended to a more complex system under study at Cardiff University and reproduced the experimental enantioselectivity this was then used to suggest possible improvements to enhance the ee of this system.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available