Evolvable process design
Parekh, Hemal (2011) Evolvable process design. PhD thesis, University of Warwick.
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The aim of this project lied in the development of an Evolvable Process Design (EPD) reactor platform such that 'evolved' chemical reactions could be investigated for the first time. The development of this 'machine' would allow us to take small organic / inorganic building blocks and use them to prepare any theoretical compound with any theoretical property that is determined by the 'machine'. One of the essential components required were building blocks that can reversibly react under various conditions until a product with a desired property has been evolved. As we were developing a proof-of-principle EPD, we at Warwick concentrated on synthesizing a library of uniquely coloured imine products to prove a desired coloured imine could be evolved in the 'machine'. For this we first required a suitable analytical method that could accurately detect multiple components in a mixture (three aldehydes, three amines resulting in nine imine products) so we could understand the reaction before placing into the 'machine'. In chapter 2, we demonstrated that 19F NMR spectroscopy was sufficient to monitor in real time the equilibrium of a 3 x 3 matrix of fluorinated amine + aldehyde building blocks (nine imines). We also demonstrated that the system of our study was under a dynamic equilibrium and that by altering the acid or base concentrations, we can affect the dynamics of the reaction and monitor it quantitatively. In chapter 3, we synthesized a library of highly conjugated aromatic imines from fluorinated aldehydes and non-fluorinated amines. These imines possessed unique UV / Vis profiles (and unique 19F NMR data) therefore could be monitored in our 'machine' equipped with a UV / Vis sensor. In chapter 4, a reaction was ready to be trailed on the 'machine' as previously synthesized in chapter three but no such 'machine' had been developed by our collaborators and therefore we created our own mini-flow system to test in situ UV / Vis absorbance measurements of our library of imines. In chapter 5 we focused on synthesizing imine ligands for metal mediated atom transfer radical cyclization reactions (ATRC) (extensively studied by the Clark group) as this 'machine' was still under development by our collaborators. We knew that once the 'machine' was developed, we could tweak the system in a way which would allow us to develop optimised imine catalysts for ATRC reactions. In chapter 6 we demonstrated KBH4 to be the most efficient reducing agent for copper mediated AGET / ARGET – ATRC and by increasing the concentration of the reaction mixtures we significantly improved the efficiency of copper mediated AGET–ATRC of previously investigated reactions by the Clark group. We also demonstrated copper mediated AGET-ATRC in water at good conversions using ultrasound, replacing a toxic solvent and may now be considered as 'green' chemistry. In chapter 7, we were able to demonstrate an alternative procedure to oxindoles via copper meditated cyclisation reaction. In the presence of 1.1 equiv. of CuBr / TPA in methanol at 50 oC we were able to show 100% conversions of substrates 2-Bromo-N-butyl-2-methyl-N-(p-tolyl)propanamide and 2-Bromo-Nbutyl- 2-methyl-N-(m-tolyl)propanamide. We then performed a series of reactions to reduce the transition metal and ligand loadings by using borohydride reducing agents but unfortunately, these reactions were not that efficient.
|Item Type:||Thesis or Dissertation (PhD)|
|Subjects:||Q Science > QD Chemistry|
|Library of Congress Subject Headings (LCSH):||Chemical reactions, Imines -- Synthesis|
|Institution:||University of Warwick|
|Theses Department:||Department of Chemistry|
|Supervisor(s)/Advisor:||Clark, Andrew J.|
|Extent:||xiii, 286 leaves : ill.|
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