Abstract:

Three β-hydroxyimino ligands: (2,6-^emPr₂C₆H₃)N＝C(Ph)CH₂CH(Ph)OH(1a), (2,6-^emPr₂C₆H₃)N＝C(Ph)CH₂C(Ph)₂OH(1b), (2,6-^emPr₂C₆H₃)N＝C(Ph)CH₂C(C₁₂H₈)OH(1c) and their bis-ligated complexes: [(2,6-^emPr₂C₆H₃)N＝C(Ph)CH₂CH(Ph)O]₂TiCl₂(2a), [(2,6-^emPr₂C₆H₃)N＝C·(Ph)CH₂C(Ph)₂O]₂TiCl₂(2b) and [(2,6-^emPr₂C₆H₃)N＝C(Ph)CH₂C(C₁₂H₈)O]₂TiCl₂(2c) were synthesized. The structures of the ligands and complexex were characterized by ¹H NMR, MS and IR. In the presence of methylaluminoxane (MAO) as cocatalyst, the effects of experimental conditions in which Al/Ti molar ratio, time, temperature and pressure were varied on ethylene polymerization by catalyst 2b were investigated. These catalysts can produce polyethylene(PE) with very high molecular weight under the broad reaction conditions. The melt points of all PE samples are around 140℃. The results of ethylene polymerization by 2a-2c show that the bulky of substituents on the β-carbon influents on the catalytic activities very much. The catalyst 2b with two phenyl groups on the β-carbon gives the best catalytic activity among the three complexes.

Key words: β-Hydroxyimino ligand, Bis(β-hydroxyimino)titanium complex, Methylaluminoxane as co catalyst, Ethylene polymerization