Piperylene concentrate, the five-carbon olefin and diolefin by-product of ethylene production, is being produced in increasing quantities as liquid feedstocks become more prevalent. At present, the concentrate is used primarily in resin production for the adhesives industry. Since this use is economically unattractive, a separation of the concentrate into pure compounds is industrially desirable. The evaluation of the effectiveness of several solvents for extractive distillation of piperylene concentrate was performed. This study resulted in the selection of acetonitrile as the most effective and most economical solvent investigated. Various distillation conditions were studied and optimization was based on these results.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

No description available.

Ph.D. (Chemistry) / Rhodium-catalyzed hydroformylation is one of the most important industrial processes for the production of linear and branch aldehydes. Aldehydes serve as intermediates in the production of various fine chemicals. Rh-based homogeneous catalysts for aldehydes production have demonstrated high yields and selectivity. Catalyst separation and recovery of expensive Rh-metal from reaction mixtures is a challenge to this process. With increasing industrial demand for highly selective processes, homogeneous catalysis could well be extensively employed if catalyst recovery from products and recyclability could be accomplished more efficiently and economically. The above problems justify the investigation of immobilized (heterogenized) catalysts by both academia and industry. This would solve the separation problem by making it possible to separate the catalyst from the reaction medium with simple filtration techniques and to regenerate the catalyst for reuse. Moreover, the ease of recovery of catalyst from products and reusability can minimize the impact of the process on the environment. Immobilization of metal complexes on solid supports is an effective approach to overcome the limitations of homogeneous catalysis. Support materials such as Mobil Composite Material (MCM-41) and Santa Barbara Amorphous type material (SBA-15) are attractive candidates for immobilizing metal complexes because of their high surface area, adjustable pore sizes, large pore volumes and high surface silanol groups. In the present work, mesoporous silica supports, MCM-41 and SBA-15 were synthesized. Rhodium(I) complex species, trans-aquacarbonyl bis(triphenylphosphine) [Rh(CO)(OH2)(PPh3)2]OTf and trans-aquacarbonyl bis{tris-(m-sulfonphenyl)-phosphine} [Rh(CO)(OH2)(TPPTS)2]OTf were synthesized as catalyst precursors and anchored onto the mesoporous MCM-41 and SBA-15 framework structure via an electrostatic method to form immobilized (heterogenized) catalysts. The support and catalyst were characterized using a range of solid-state techniques. Results showed that the structural integrity of the catalyst supports was maintained after immobilization. Results also revealed a strong interaction between rhodium complex species and the inner walls of the ordered mesoporous materials, thus leading to the formation of stable heterogenized catalysts. In addition, immobilized catalysts constrained the pores, thus leading to a confinement effect, which enhanced activity and regioselectivity in the hydroformylation process. Selected immobilized catalysts were...

M.Sc. / Polymerization of a-olefins by metallocene-based catalysts, is an ever expanding field with current scientific research continuing in an endeavor to develop chiral catalysts with greater stereospecificity and activities. However, the application of metallocene catalysts in oligomerization reactions of a-olefins has been somewhat neglected. This is despite the fact that metallocene catalysis can offer a convenient route to the synthesis of higher a-olefin oligomers. Furthermore, by utilizing an assortment of functional group transformations, a-olefin oligomers can serve as intermediates for a variety of specialty chemicals. Notwithstanding the possibility of employing alternative ligands in catalysis, the use of non-cyclopentadienyl-based complexes is a topic that has only recently been considered. Comparative studies of a series of analogous complexes is lacking in this field and thus a pertinent study of a number of known metallocene complexes was executed in this project. Furthermore, an industrially applicable process for oligomerization was sought after. This was in fact achieved by subjecting the a-olefins 1-pentene, 1- hexene and 1-octene, to oligomerization conditions with a previously unreported and lowered methylaluminoxane ratio. This reaction proved to be highly selective to dimer formation of the three aforementioned higher a-olefins. In order to gain more insight into the oligomerization process, the progress of the reaction was also followed. Only zirconium complexes were synthesized and furthermore, the induction of oligomerization as opposed to polymerization (using compounds known to be active solely as polymerization catalysts), was attempted by increasing the reaction temperature. The second part of this project entailed the synthesis and subsequent testing of zirconium catalysts containing non-cyclopenatadienyl-based ligands. These complexes have frameworks with chelating phenolate or naphtholate ligands. These complexes were tested for oligomerization, but results proved to be negative.

Modern synthetic chemistry is unimaginable without transition metal catalysis. Yet the often high cost, toxicity and scarcity of many transition metals is driving attempts to find sustainable alternatives. Thus, the development of catalytic processes using main-group catalysts is now of broad interest. This thesis reports the development of a facile protocol for the aluminium-catalysed hydroboration of alkynes, alkenes and polar bonds using commercially-available catalysts. The catalytic hydroboration is proposed to occur by hydroalumination followed by product release through σ-bond metathesis with pinacol borane. An alternative route to alkenyl boranes is the 1,1-carboboration of alkynes using stoichiometric B(C6F5)3. A zwitterionic intermediate in the Piers' borane-catalysed hydroboration and 1,1-carboboration of alkynes with B(C6F5)3 has been characterised and its divergent reactivity identified. This has led to the development of a B(C6F5)3 - catalysed hydroboration of alkynes using HBpin.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (M.Ch.E.)--University of Delaware, 2009. / Principal faculty advisor: Mark A. Barteau, Dept. of Chemical Engineering. Includes bibliographical references.

No description available.

No description available.