Exploring reactor design to harness reactive intermediates

McBride, Tom 2021. Exploring reactor design to harness reactive intermediates. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

This thesis explores the design and engineering of flow reactors to facilitate synthetic organic transformations. The designs of these flow reactors are focussed on manipulating and controlling reactive intermediates in situ and enabling the facile use of acetylene gas; acyl ketenes; and biphasic systems, as useful synthetic tools. Initially, this thesis explores the use of generating acetylene gas in situ without the use of a resident gas cylinder from commercially available calcium carbide. The calcium carbide is formulated into an applicable flow reagent for the safe generation of acetylene gas in a continuous manner. Acetylene gas is intercepted via various organic transformations thus constructing telescoped flow systems. The aim to generated and harness acetylene gas in situ via intricate design of reactor has been met and successfully explored. Secondly, utilising flow’s excellent ability of thermal control, the thermolysis of an acyl ketene precursor is explored. In this section, a flow reactor is designed to thermally decomposed an acyl ketene precursor thus liberate an acyl ketene in situ. This highly reactive intermediate is explored and incepted with various ketene traps yielding β-keto esters/amides and functionalised novel coumarins. Post-functionalisation of the synthesised β-keto ester feedstocks are further explored by the Biginelli reaction catalysed by pyridinium triflates in neat microwave conditions. Therefore, a tandem flow-microwave processing system is designed to work towards the synthesis of a compound library. Finally, flow reactor design is explored to synthesise Civetone, a natural musk fragrance, in continuous flow via a Dieckmann macrocyclisation. This transformation is commonly biphasic (liquid-solid reaction mixture) and can therefore cause blockages in flow processing. The use of Continually Stirred Tank Reactors (CSTRs) are explored to facilitate the difficult handling of a biphasic flow reaction and promote the macrocyclisation (and scale up) towards the synthesis of natural product, Civetone, via ‘mimicked’ dropwise addition in flow. The chapters of this thesis primarily focus on how a flow reactor can be constructed to enable and harness highly reactive intermediates and explore the chemical space of these transformations.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Chemistry
Funders:	EPSRC
Date of First Compliant Deposit:	16 February 2022
Last Modified:	16 Feb 2023 02:30
URI:	https://orca.cardiff.ac.uk/id/eprint/147532

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