The Study Of Synthesis Of Pyridine-Imine N,N-Nickel Complexes And Their Applications In Ethylene Polymerization

In this dissertation,2-?hydroxymethyl?-tetrahydroquinolin-8-one was syntheized in a four-step sequence using 2-chloro-tetrahydroquinolin-8-one as the raw material.Then,a series of 2-acetyloxymethyl-tetrahydroquinolin-8-arylimine-nickel dichloride?Ni1–Ni6?were prepared in a?one-pot?reaction with 2-?hydroxymethyl?-tetrahydro quinolin-8-one,substituted anilines and nickel dichloride hexahydrate.With these catalysts,their catalytic performace in ethylene polyerization was detailed studied.The investigation results showed that either the structure of nickel complexes or the reaction conditions could significantly influence the distribution of oligomers and the selecticity of?-olefins.It was found that there were some electronic effect on metal centers when changing the substituents of the complexes.Thereby,the microstructure of oligomers and the selectivity of?-olefins could be precisely regulated.The research details are as follows:?1?Based on a brief overview of the development history in polyethylene industry,the present trend and the research progress of late transition metal-catalyzed ethylene polymerization has always been on the increase in the past decades;to this end,another novel series of nickel complex pre-catalysts were synthesized and fully characterized;thus their catalytic performance toward ethylene polymerization was investigated.Then,the significance of this dissertation was presented.?2?The 2-?hydroxymethyl?-tetrahydroquinolin-8-one was synthesized by2-chloro-tetrahydroquinolinone as the starting material.And a one-pot template reaction was used to synthesize six analogues 2-acetyloxymethyl-tetrahydroquinolin-8-arylimine-nickel dichloride complexes.All the nickel complexes were characterized by infrared spectroscopy and elemental analysis.Among them,the Ni2 and Ni3.H₂O have additionally been the subject of single crystal X-ray diffraction studies due to their binuclear and mononuclear nature respectively.While the acetyloxymethyl group remained uncoordinated in both structures.?3?These complexes were used in ethylene polymerization and their potency was evaluated.By changing the polymerization conditions such as co-catalyst types,Al/Ni,temperature and the substituents,various polymer products were obtained.In addition,upon activation with MMAO,48%of 1-hexenes was formed as the major product of ethylene oligomerization along with minor quantities of butenes.Complex Ni4 displyed C₂H₄ respectively.In comparison with MAO as co-catalyst,all the nickel complexes exhibited lower activities but showed a specificity towards ethylene dimerization,with selectivity for 1-butene?C4:64-99%?.Furthermore,sizable induction periods were a feature of the MAO runs with Ni1/MAO reaching peak catalytic activity only after 45minutes.