Studies On Synthesis,Characterization,and Catalytic Properties Of Metal Complexes Supported By Amine-Tri(Phenolate) Tetradentate Ligands

Polyolefins have become one of the most widely used synthetic resin materials in the world due to their advantages,such as low cost,easy to producing and processing,superior performance.As the soul of the polyolefin industry,Catalysts,which determines polymers' internal structure and morphology,play an important role in the development of this field.After several decades of developing,polyolefin catalysts have been stepped into a new period of non-metallocene catalyst.Since these catalysts can be well controlled to produce a specific functional material by adjusting different electron groups and specific spatial configurations,so they have become the current focus of olefin polymerization catalysts' research field.In order to obtain a class of non-metallocene catalysts with high catalytic activity,good thermal stability and long service life,we designed a series of tetradentate ligands with amine bridged tri(phenolate)[ONOO] type and obtained their titanium complexes,totally 14 species.The second chapter of this paper mainly describes the preparation process of the experiments,and it also describes the synthesis and characterization of some basic raw materials.In this chapter,five kinds of amine derivatives and three kinds of bromine derivatives were obtained.The third chapter is the synthesis of the ligands,L1H3-L14H3,by using the improved experimental method and the raw materials prepared in Chapter 2,1HNMR and 13 CNMR characterization confirms the structure of these compounds;Then,the ligands reacts with Ti Cl4 by an improved one-pot method to obtain the complexes C1-C14 with a high yield.The complexes C1-C14 are characterized by 1HNMR,13 CNMR and elemental analysis,besides the single crystal of the complexes C1 and C9,after Xray diffraction analysis,confirms the general structure of these compounds: The bridged nitrogen atom coordinates to the central metal atom,forming a coordination bond.The three O-forms ? bonds with the metal titanium;The central metal titanium atom,in the center of a twisted hexahedron,contacts with O1,O2,O3,N1 and Cl1 to form a fivecoordinate compounds.Chapter 4 explores the catalytic activity of the complexes C1-C14 for ethylene polymerization.The regular changes of the polymerization activity with the changes of the substituent are as follows: When R3 is fixed,the activity of the ethylene polymerization increases firstly and then decreases with increasing of the substituents of R1,the molecular weight of the polymer basically shows a trend of first increase and then decrease.By screening and comparison,a variety of catalysts with excellent performance are obtained: most of them have high catalytic activity in the polymerization of ethylene,some of them even can catalyze the ethylene's polymerization to produce the polyethylene with high molecular weight.Of all the catalysts,the highest catalytic activity is obtained by complex C13: 93264 kg PE/(mol Ti·h),complex C9 catalyzes ethylene polymerization to obtain linear polyethylene whose molecular weight is up to 208.3×104 g/mol.Complex C4 was selected to study the thermal stability and catalytic life of the catalysts.It was found that this catalyst could polymerize ethylene in a high activity at 100 ?.When polymerizing at 60 ? for 2.5 h,the catalyst C4 can still maintain a high catalytic activity.These catalysts' excellent performance in high catalytic activity,good thermal stability,long catalytic life and catalyzing ethylene polymerization to obtain linear polyethylene with high molecular weight makes them basically reach the original purpose of this paper.