Thesis
Investigating the formation of aryl radicals from aryl halides mediated by transition metals and alkali metal alkoxides
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2026
- Thesis identifier
- T18025
- Person Identifier (Local)
- 202153778
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- Aryl halides are commonly employed as aryl radical precursors, through activation by single electron-transfer (SET) or halogen atom transfer (XAT). For over a century alkali metal alkoxides alone have been shown to activate aryl halides to form aryl radials, but the mechanism by which this occurs has not been clear. Many authors have proposed that alkoxides undergo ground-state SET to the aryl halide, but key evidence for this has been missing. In Chapter 2 of this thesis, this proposal is refuted, and instead evidence is presented that alkali metal alkoxides initiate chain reactions through the formation of benzynes. Substrates including I, II, and III were investigated, along with their deuterated analogues, and removal of H+ or D+ is shown to control the formation of aryl radicals from aryl halides. [see figure in thesis] The high reactivity of aryl radicals makes their identification in organic reactions challenging, particularly where products could alternatively arise from competing twoelectron transition metal-mediated pathways. In Chapter 3, a recently developed aryl radical assay employing substrate IV is used to directly probe radical formation from aryl halides in the presence of nickel species under ground-state conditions. Formation of aryl radicals in benzene with a suitable base produces a characteristic VI : V product ratio of ca. 4, providing a clear diagnostic signature. Air-stable Ni(COD)(DQ) is shown to promote the efficient coupling of aryl halides with benzene via aryl radical intermediates. [see figure in thesis] In Chapter 4, the assay is extended to palladium systems under both thermal and photoexcited conditions. Under thermal conditions, evidence is obtained that Pd⁰ complexes generate aryl radicals from aryl halides, with ligand-dependent control over radical formation. Under visible light irradiation, the results of the assay further support the activation of aryl halides to form “Pd-radical hybrid” species, in line with recent photochemical cross-coupling studies.
- Advisor / supervisor
- Murphy, John
- Resource Type
- DOI
- Funder
- Embargo Note
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File | 2026-06-10 | Embargo |