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Structural and mechanistic studies of catalysts

Synthesis and characterisation of tetracyc1ic guanidinium phase transfer catalysts I and 11 from ethyl (R)-3-hydroxybutyrate was undertaken as well as the determnination of their pKa's to provide insight into the mechanism of their use in phase transfer catalysis. Their proficiency at catalysing the Michael addition of 2-hydroxy-l ,4-napth~guinone III to trans-~nitrostyrene IV was studied. Catalyst 11 showing improved reaction times and e.e.' s over I. The synthesis oftetracyc1ic guanidinium salt V was also attempted unsuccessfully, Synthesis of copper (1) hydride (CuH.X, X = H20 and pyridine) from three different routes (Wurtz Reaction [1], NaBH4 reduction [2] LiAIH4 reduction in pyridine [3]) and their subsequent investigation by inelastic neutron scattering (INS) techniques (neutron diffraction/spectroscopy) and X-Ray diffraction (XRD) provided insight into the structure of the copper hydride core and also the nature of the stabilising surface shell (H20 and pyridine respectively). Direct synthesis of Stryker's reagent [HCU{P(C6H5)3}]6 from copper (ll) acetate (Cu(OAc)2) and also its deuterium analogues [DCu{P(C6H5)3}]6 and [HCu{P(C6D5)3}]6 were achieved and the location of their hydride ligands using INS (SANDALS - neutron diffraction) was detennined. ; Synthesis of organometallic his-(n2 -π-allyl)M (M = Ni VI & Pd VII) cross-coupling catalysts from the Grignard reaction of metal halides and preparation of active Ni-terpyridyl complexes (general formula LNih, L = TPY) VIII - XI from the reaction of Ni(CODh and h with the starting material TPY's was achieved and vibrational INS spectra (TOSCA - neutron spectroscopy) was used to investigate the low energy vibrations which are linked to catalytic activity. Similar studies were performed on the commercially available Pd stabilised NHC PEPPSl pre-catalysts (IPr XII and IMes XIII)).

Identiferoai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:664598
Date January 2013
CreatorsBennett, Elliot Leon
PublisherBangor University
Source SetsEthos UK
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation

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