首页|High Temperature Iron Ethylene Polymerization Catalysts Bearing N,N,N'-2-(1-(2,4-Dibenzhydryl-6-fluorophenylimino)ethyl)-6-(1-(arylphenylimino)ethyl)pyridines
High Temperature Iron Ethylene Polymerization Catalysts Bearing N,N,N'-2-(1-(2,4-Dibenzhydryl-6-fluorophenylimino)ethyl)-6-(1-(arylphenylimino)ethyl)pyridines
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The N,N,N'-ferrous chloride complexes,[2-{CMeN(2,4-(CHPh)2-6-FC6H2))-6-(CMeNAr)C5H3N]FeCl2(Ar=2,6-Me2C6H3 Fe1,2,6-Et2C6H3 Fe2,2,6-iPr2C6H3 Fe3,2,4,6-Me3C6H2 Fe4 and 2,6-Et2-4-MeC6H2 Fe5),each possessing one N-2,4-dibenzhydryl-6-fluorophenyl group,were readily synthesized from their respective unsymmetrical bis(imino)pyridines,L1-L5.Structural identification of Fe2 highlighted the variation in the steric properties provided by the dissimilar N-aryl groups.Following pre-treatment with either MAO or MMAO,complexes Fe1-Fe5 all displayed,at an operating temperature of 80 ℃,high activities for ethylene polymerization with levels falling in the order:Fe4＞Fe1＞Fe5＞Fe2＞Fe3.Notably,Fe4/MAO displayed the highest activity of 1.94×107 gPE·molFe-1-h-1 of the study with only a modest loss in performance at 90 ℃.Generally,the resulting polyethylenes were highly linear(Tm range:122-132 ℃),narrowly disperse and of low molecular weight(MW range:6.73-46.04 kg·mol-1),with the most sterically hindered Fe3 forming the highest molecular weight polymer of the series.End-group analysis by1H-and 13C-NMR spectroscopy revealed saturated alkyl(n-propyl and i-propyl)and unsaturated vinyl chain ends indicative of the role of both β-H elimination and chain transfer to aluminum as termination pathways.By comparison with previously reported iron precatalysts with similar tridentate ligand skeletons,it is evident that the introduction of a large benzhydryl group in combination with a fluorine as the ortho-substituents of one N-aryl group has the effect of enhancing thermal stability of the iron polymerization catalyst whilst maintaining appreciable polymer molecular weight.
Iron catalystEthylene polymerizationLinear polyethyleneFluoride effectThermal stability
Chantsalnyam Bariashir、Qiu-Yue Zhang、Bayasgalan Ulambayar、Gregory A.Solan、Tong-Ling Liang、Wen-Hua Sun
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Institute of Chemistry and Chemical Technology,Mongolian Academy of Sciences,Ulaanbaatar 13330,Mongolia
Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science,Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190 China
Department of Chemistry,University of Leicester,University Road,Leicester LE1 7RH,UK
State Key Laboratory for Oxo Synthesis and Selective Oxidation,Lanzhou Institute of Chemical Physics,Chinese Academy of Sciences,Lanzhou 730000,China
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