טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentRodensky Michal
SubjectCatalytic Activity of Group 4 Octahedral Complexes
DepartmentDepartment of Chemistry
Supervisor Professor Moris Eisen


Abstract

One of the most important polyolefins in the industry is polypropylene. Its relatively low cost as well as the possibility to engineer its mechanical properties has made this polymer and the research regarding it so popular.

The main goal of this research was to examine the activity and mechanism of octahedral catalytic systems of group 4 transition metals with heteroallylic ligands in the polymerization of propylene. We have examined two type of complexes using the acetylacetonate ancillary ligand, titanium(bisacetylacetonate)dichloride and zirconium(bisacetylacetonate)dichloride. The catalysis of the polymerization of propylene using these organometallic complexes and MAO as the co-catalyst has produced unique results. Examining the results of these reactions while taking into account all possible interactions with the active site we have come to several important conclusions. We have shown that these catalytic systems could have more than one active catalytic site - depending on solvent. We have also concluded that due to interactions of the solvent to one of the empty orbitals of the metal both the activity of the catalyst and isotacticity of the polymer obtained are strongly depended on the solvent. We also concluded that α - agostic interactions play an important role during the polymerization. An additional reaction that was examined was the isomerization of α-olefins. The isomerization of 1-octene using titanium(bisacetylacetonate)-dichloride and MAO as the catalytic system took place. From analyzing the isomerization products two plausible mechanisms for the reaction were suggested. The synthesis of 3-phenylpropene-3,3-d2 and its reaction using a benzamidinate based catalytic system allow us to conclude which was  the main mechanism for the isomerization reaction.