Transition metal catalyzed olefin polymerizations including mechanistic investigations.

摘要

The combination of tantalum(V) chloride and an alkylating agent was found to catalyze the selective trimerization of ethene to 1-hexene in chlorobenzene at 45–60°C. A rate in excess of 500 turnovers/mol Ta•hr with 96–99% selectivity for 1-hexene has been observed. Mechanistic studies using methylating agents indicate that Ta(CH₃)₂Cl ₃ is the single-site precursor to the active catalyst.; The copolymerization of ethene with norbornene derivatives, as well as their terpolymerization with 1-alkenes, using a series of neutral, square planar nickel complexes containing anionic P∼O chelates is described. In copolymerizations of norbornene derivatives bearing oxygen functionalities, the level of incorporation is lower than parent norbornene, as are the reaction rates and polymer molecular weights. In the case of terpolymerization of ethene and norbornene with 1-alkenes, the polymer molecular weights tend to be low because of slower monomer insertion and additional chain-transfer pathways that are available following 1-alkene insertion.; The palladium-catalyzed copolymerization of functionalized norbornenes is described. The reactivity ratios for two sets of monomers were measured using linear and non-linear techniques. Differences in the reactivity ratios of butyl norbornene and norbornene ethyl ester for the two catalysts were significant. In addition to reactivity ratios, the conversion of individual monomers over time has been studied. Following the conversion of butyl norbornene it was possible to survey the hinderance of polymerization by norbornene ethyl ester while norbornene methyl acetate did not hinder the polymerization. Preference for the exo isomer was observed for all norbornenes studied with one exception. When norbornene ethyl ester is homopolymerized it shows the expected exo isomer preference however when copolymerized the preference is lost. This change in isomer preference has helped to shape a proposed mechanism for the copolymerization of functionalized norbornenes.; The synthesis and anchoring of novel ionic liquids to surfaces is described. Carboxylic acid terminated and siloxide terminated methyl-imidazolium ionic liquids have been synthesized and characterized. Attachment of these ionic liquids to aluminum and silicon surfaces is described. Characterization of the aluminum compounds was performed using SEM and EDAX. Characterization of silicon surfaces was performed using ellipsometry and IR.