Carter, Eve;
(2022)
Novel reactions using transaminases and strategies for upgrading lignin to higher value synthons.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
There is an increasing requirement for more sustainable materials and processes in synthetic chemistry. This can be achieved by developing and using more environmentally benign methods and catalysts as well as utilising waste materials in synthesis. In this PhD, enzymes were employed as renewable catalysts in a new synthetic application, mechanochemical processes were developed for the first time with non-hydrolytic enzymes, and lignin was investigated in preliminary experiments as a sustainable biomass-derived alternative to oil-based feedstocks. Chapter 1 describes the background of the project including an introduction to green chemistry, the enzymes employed in this work and lignin. Transaminases are widely used to transform a ketone or aldehyde group into an amine. In chapter 2, the use of transaminases is described in a new application for the direct conversion of a hydrazone into an amine. Several hydrazone substrates were investigated; in particular, the amination of SAMP hydrazones gave promising results as a high yielding and sustainable method to form chiral β-substituted amines. Mechanochemistry is increasingly being explored as a sustainable synthetic method. In chapter 3, for the first time, the application of transaminases under mechanoenzymatic conditions with aldehydes and ketones is presented, where amines were formed with high yields and stereoselectivities. The direct use of whole cells was possible, eliminating the need for enzyme lysate preparation and purification steps. Lignin is a high volume non-edible waste product from the paper industry which is rich in aromatic moieties. To enable the utilisation of lignin as a feedstock, new methods for its selective depolymerisation and functionalisation are required. One approach, described in chapter 4, used chemical methods for the selective oxidation of lignin. Cleavage was then attempted with a nucleophile. Depolymerisations with tyrosinase enzymes and mechanoenzymatic cascades using transaminases are presented in chapter 5.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Novel reactions using transaminases and strategies for upgrading lignin to higher value synthons |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2022. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry UCL > Provost and Vice Provost Offices > UCL BEAMS UCL |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10156941 |
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