Thesis
The development of powerful electron-transfer reagents
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2010
- Thesis identifier
- T12757
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- This thesis discusses the investigation into powerful electron-transfer reagents conducted in the research group of Professor John Murphy at the University of Strathclyde between October 2006 and March 2010. Chapter one discusses the principal themes and areas of chemical research that are contained within this thesis, providing useful background information. Section 1.1 introduces electrontransfer using metals and metal-based reagents, including the use of dissolving group 1 (and 2) metal reductions, transition metals and lanthanides. Section 1.2 discusses organic electron-transfer reagents, focussing on the development of more powerful reagents. Section 1.3 focuses on N-heterocyclic carbenes (NHCs), including their structure and properties, their use as organocatalysts and their employment as ligands. Finally, section 1.4 introduces the theme of electron-transfer using nickel complexes, including the formation of aldehydes using nickel(I) salen and the employment of nickel(0) and NHCs in the reduction of organic substrates. Chapters two, three and four discuss the results obtained during the development of powerful electron-transfer reagents. Chapter two reveals the surprising isolation of alcohols (e.g., 2.6) following the reduction of alkyl halides (e.g., 2.1) using a powerful organic electron-donor 1.150 (scheme i). The substrate scope is revealed, followed by mechanistic studies that investigate the mechanism that leads to alcohol formation. Several pathways were ruled out, allowing a single mechanism to be postulated as the most likely route for this transformation. Scheme i: the isolation of alcohol 2.6 from alkyl iodide 2.1 using organic electron donor 1.150. Chapter three discusses a novel, nickel(II) crown carbene complex 3.1 that, when activated, is a powerful electron-donor (figure i). The activated nickel complex, formed by treatment with sodium amalgam, is a powerful reductant that reduces carbonyl-containing compounds, both activated and non-activated sulfones and sulfonamides and the central aromatic ring of anthracene (and substituted analogues) in a Birch reduction. Extensive investigations into the active species using control experiments, cyclic voltammetry and computational analysis reveal the active species to be a nickel(II) ion bound to a di-anion ligand. Figure i: the structure of nickel(II) crown carbene complex 3.1. Chapter four describes attempts to formulate a catalytic, reductive procedure using electrochemical cycling to generate the catalytic electron-donor 1.177 (scheme ii). The screening of various proton sources is discussed, as well as the synthetic procedures used and the challenges still ahead. Scheme ii: the reduction of aryl halide 4.4 using electrochemically generated donor 1.177. Finally, Chapter five contains the experimental procedures and data for all synthesised compounds discussed within this thesis.
- Resource Type
- Note
- This thesis was previously held under moratorium from 9th May 2011 until 9th May 2013.
- DOI
- Date Created
- 2010
- Former identifier
- 821633
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