Synthesis Of Phenoxy-ester Ligated Early Transition Metal Catalysts And Their Properties

Ethylene propylene rubber (EPR) is a general term of ethylene-propylene methylenecopolymer and ethylene-propylene-diene-terpolymer rubber and its output ranks third. It isone of the fast growing synthetic rubber varieties since the1980s. EPR is widely used inautomobile industry, construction and other fields due to its excellent aging resistance (ozoneresistance, heat resistance, and weather resistance), chemical attack resistance, goodelectrical insulating properties and low density.The key of ethylene propylene copolymerization technology lies in the catalysts. Basedon the new concept of “ligand-oriented catalyst design”, series of ligands were prepared byintroduction of substituents with different space steric hindrance and electronic effect tophenoxy-ester (a kind of electron donor) matrix. The novel non-metallocene single-sitecatalysts--[O, O] bidentate coordination compounds were then obtained by the reaction ofthese ligands and TiCl4. Finally catalytic activities of as-prepared catalysts for ethylenepropylene (co) polymerization were studied. The structures of polyolefins were alsocharacterized.Firstly,2,6-dibromo-4-methyl phenol was used as a starting material and treated withsilane in the first step to prepare phenoxy silane compounds (precursors) with the yield ofabove90%. Then precursors were reacted with formic acid ester to obtain5kinds ofphenoxy-ester ligands (L1~L5) containing different substituents with the yield of about50%.The structures of precursors and ligands were characterized by infrared spectrometer (FT-IR),nuclear magnetic resonance (NMR) and mass spectrum (MS).Secondly, the ligands L1~L5respectively were reacted with n-butyl lithium, then treatedwith titanium tetrachloride to obtain five phenoxy-ester ligated titanium complexes. Thestructures of the complexes were characterized by FT-IR, NMR and MS.Finally, in order to study the catalytic performances of phenoxy-ester ligated earlytransition metal catalysts for ethylene polymerization, propylene polymerization andethylene propylene copolymerization, bis[5-methyl-3-trimethylsilyl phenyl salicylate]titanium (IV) dichloride was used as the catalyst for polymerization together withiBu3A1/Ph3CB(C6F5)4as the cocatalyst in toluene. It was found that the as-prepared catalystdisplayed activity for both polymerization and copolymerization. As-obtained ethylenepropylene copolymer was random copolymer. The glass transition temperature of the copolymer was-43.3°C. The link ratios of ethylene to propylene were between0.89and1.26. Ethylene content in the copolymer was declining with the increase of propylene contentin the flow ratios.