Catalysis by gold

Davies, Scott 2017. Catalysis by gold. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

The oxidation of benzyl alcohol over supported Au, Pd and AuPd catalysts on a range of metal oxide supports was investigated using a Radley’s Starfish Reactor. Reaction conditions such as temperature, solvent, support and metal loading were varied in order to obtain insight into benzyl alcohol oxidation. All catalysts were prepared using the sol immobilisation technique. It was discovered that AuPd bimetallic catalysts were most active for benzyl alcohol oxidation, in a ratio of 1:1 Au:Pd. Further, substituted benzyl alcohol compounds were oxidised using AuPd catalysts in order to investigate the mechanistic properties of benzyl alcohol oxidation. By conducting the Hammett methodology on a range of substituents, mechanistic insight into the reaction was possible due to the electronic effects substituent groups had on the parent benzyl alcohol molecule. The results from these experiments indicate that a transition state with a formal charge is being created as the reaction proceeds and electron donating groups such as MeO in the para- position was able to stabilise this transition state and promote the oxidation reaction, resulting in a higher rate of reaction. Lastly, cinnamyl alcohol was subjected to the same oxidation reactions as benzyl alcohol in order to assess how a structural variant of benzyl alcohol is affected by varying certain catalytic parameters such as temperature, support and solvent. It was found that cinnamyl alcohol undergoes similar reactions as benzyl alcohol and the major oxidation product is the corresponding cinnamaldehyde. Differing supports had different effects on the oxidation, with disproportionation being suppressed on certain supports. Higher temperature also promoted hydrogenation of cinnamyl alcohol.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Chemistry
Subjects:	Q Science > QD Chemistry
Date of First Compliant Deposit:	19 May 2017
Last Modified:	20 Apr 2021 10:56
URI:	https://orca.cardiff.ac.uk/id/eprint/100727

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