Thesis (Ph. D.)--University of Hong Kong, 1994. / Includes bibliographical references (leaves 242-250).

Thesis (Ph. D.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 136-145).

Thesis (Ph. D.)--University of Hong Kong, 1994. / "1994"--Cover. Includes bibliographical references (leaves 200-210).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1951. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves [80]-82).

Thesis (Ph. D.)--University of Chicago, Dept. of Chemistry, March 2003. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph.D.) - University of St Andrews, November 2009.

The objective of the research described in this dissertation was the search for optimum ligand-metal complex combination that would facilitate the contrathermodynamic isomerisation of internal olefins. To this end a variety of ligands where synthesised and subsequently tested, firstly for their ability to isomerise alpha olefins and secondly their ability to isomerise internal olefins. Due to the lack of information obtainable from literature about catalytic isomerisation of olefins, the general reaction parameters had to be investigated. Various factors that could play a role in the isomerisation of olefins where investigated and these included the effect that solvents have on the isomerisation as well as the possibility of metalhydride formation. The possible formation of metal-hydrides was tested by adding a variety of acids and also the addition of hydrogen gas to the solution. All of these factors played an important role in the subsequent isomerisation of alkenes and valuable data could be obtained from these experiments. Solvents were found to have an effect on the isomerisation, but a trend could not be established. The effect of added acid was more pronounced and a correlation between acid strength and isomerisation could be established. It was also found that hydrogen gas added to the reaction mixture generally increased the reactivity of the metal catalysts and some experiments were done to optimise the use of hydrogen in these reactions. The use of commercially available ligands for the isomerisation reaction was also investigated and gave a broad indication of possible active ligands. After these initial reactions and information gathered from literature, it was decided to synthesise a set of di-imine ligands and also a set of bis-phisphite ligands. Due to tautomerism of the di-imines to the corresponding enamines, a set of enamine/imine ligands was synthesised and tested with two rhodium and two palladium catalysts. The synthesis of bis-phosphite ligands was initially problematic, but ideal conditions were found and a set of bis-phosphite ligands was synthesised and tested. Results obtained from the testing of both the enamine/imine lignds as well as the bisiii phosphite ligands were of value and a great many trends could be observed. Many of these observations had correlations to either the electronic nature of the various ligands as well as that of the metal centre. The testing of a set of palladium(II) metallocycles also gave an insight into the electronic properties necessary for the successful isomerisation of olefins. These electronic properties are always a combination of ligand and metal centre effects and thus a fine balance must be struck between these two factors. As a final conclusion to the work that was performed, internal olefins were subjected to tandem isomerisation-hydroformylation reactions using some of the more active metal-ligand systems. Internal olefins were isomerised and hydroformylated in the same reaction vessel to afford branched and linear aldehydes. In these reactions, it was proved that isomerisation as a primary reaction could be coupled to a secondary reaction and be of use in industry and further research in this field might prove to be of some value. / Prof. D.B.G. Williams

M.Sc. / The main objective of this study was to identify and optimise the homogeneous catalytic systems for Pd(II) catalysed alkene acetoxylation in acetic acid to directly yield allyl or vinyl acetates as opposed to the usual aldehydes or ketones. Part of the intention of this study was to investigate potentially suitable re-oxidants and reaction conditions suitable for industrial application. The synthesis of butenyl acetate (via 1-butene acetoxylation) in particular is regarded as a potential value-adding opportunity for solvents producers. For safety considerations the study was performed with liquid alkenes (cyclohexene, cyclopentene, cycloheptene, cyclooctene and 1-hexene). Cyclohexene was used for the bulk of these studies. One of the most important and pioneering reactions in this field is the similar system for the oxidation of alkenes to ketones (the Wacker process). The related reaction, oxidative acetoxylation, is the result of the discovery of the Wacker process. The problems associated with both these reactions is the difficulty in re-oxidising the catalyst Pd once it has been reduced in the catalytic process from Pd(II) to Pd(0). Various reaction systems have been developed to improve these processes. Some of the systems that have been developed in the acetoxylation of alkenes were investigated. From the studies it has become obvious that for ease of Pd(0) re-oxidation a co-catalyst, benzoquinone, is essential for the catalytic process. This system employing a co-catalyst required another oxygen efficient re-oxidant to oxidize hydroquinone once reduced from benzoquinone in the oxidation of Pd(0). The re-oxidant would in turn be oxidized by oxygen. Various types of re-oxidants such as Cu(II) salts, heteropolyacids and metal macrocycles (e.g. Schiff base complexes and phthalocyanine metal complexes) were investigated in the multi-step electron transfer process. The most promising of the systems was the Pd(OAc)2/ benzoquinone/ heteropolyacid (H5PMo10V2O40 .34H2O)/ O2 system. From the studies it was apparent that the type of the re-oxidant can influence the yield of the product. Various other parameters were found to influence the reaction outcome. The type of Pd(II) salt was found to be influential in the reaction, for instance Pd(OAc)2 was found to be a better catalyst than Pd(CF3CO2)2. The catalyst loading was found to improve the yield iv when increased whilst this was not trivial since Pd is expensive the system needed to have as low catalyst loading as possible. The type of alkene used dictated the rate of the reaction and the product distribution. It was found that the conditions used for cyclohexene were not transferable to other alkenes without changing certain parameters to suit the alkene in question. Cycloalkenes acetoxylation was found to proceed without the addition of the strong nucleophile additive NaOAc, whilst for 1-hexene acetoxylation the reaction did not proceed without the additive. The product distribution was found to also differ between cycloalkenes and 1-hexene. For cyclohexene the by-products observed were the disproportionation products cyclohexane and benzene. In the case of 1-hexene the by-products were 2-hexanone (the Wacker reaction) and 2-hexenes (isomerisation). The operating temperature also played a role in the reaction outcome. In some instances the increase in reaction temperature negatively affected the reaction whilst in other cases it improved the reaction. Oxygen pressure also influenced the reaction to a lesser extent, with an increase in pressure favouring the reaction.

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