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Title: The oxidation of olefins promoted by transition metal complexes
Author: John, Robert Alun
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 1981
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The oxidation of olefins by transition metal complexes leading to epoxide or ketonic products has been reviewed, with an emphasis on non-free radical processes. The formation of cycloadducts by reaction of bis (triphenylphosphine )- platinum(O)dioxygen with the α,β-unsaturated carbonyl compounds trans but-2-enal, propenal, cyclohex-2-en-1-one, exo 2-methvlenecyclohexan-1-one and 3-phenylprop- 2-enal was investigated by H- and 31P- nuclear magnetic resonance (n.m.r.). The cycloadducts derived from trans but-2-enal and propenal were thermally unstable in solution and further reacted to form stable, isolable complexes. The mechanism by which the cycloadduct cis [4-trans(prop-2-enyl )-1,1-bis( triphenyl - phosphine)platina-2,3» 5-trioxacyclopentane] , I , was transformed into cis [trans- (5-formyl-4-methyl)-1,1-bis(triphenylphosphine )platina-2 t 3-dioxacyclopentane] , II , was investigated by H- and H-n.m.r. utilising trans 4-[2H3]but-2-enal. A mechanism which involved both exchange of free trans but-2-enal with I and reaction to give II was proposed; a computer model, based upon numerical integration of the alternative rate equations was in good agreement with this proposition. The chemical reactivity of II with a variety of reagents was explored. In particular, the reaction of II with trifluoroacetic acid gave trans 2-formyl- 3-methyloxirane in high yield and stereoselectivity. The dynamic behaviour of cis[bis(triphenylphosphine)(23,3'-m)(trans - but-2-enal )platinum(0)] was observed by variable temperature P-n.m.r. and explained by the interconversion of carbonyl rotamers. The preparation of iridium(I) olefin and peroxo complexes has been described Chlorobis triphenylphosphine) (1,2-m) (ethene )dioxygen iridium( I) , III , and related complexes were found to oxidise terminal olefins to their methyl ketones stoichiometrically, by a non-free radical process. The mechanism has been discussed.
Supervisor: Brown, John M. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Alkenes ; Oxidation ; Transition metal complexes Chemistry, Inorganic