Iron-based non-metallocene catalysts for oligamerization of hexene

Abstract

Chelating bidentate ligands: diamine ligand, RHN(CH₂)₃NHR ligand (a) and diimine ligand, RHN(CH₃)C(CH₃)CNR ligand (b) and the Schiff’s base ligand, salen ligand (c) were synthesized and used for the preparation of iron complexes. Iron-based non-metallocene catalysts: [RHN(CH₂)₃NHR]FeCl₃ (cpx 1a) [RHN(CH₃)C(CH₃)CNR]FeCl₃ (cpx 2b) C₁₆H₁₄N₂O₂FeCl (cpx 3c) and C₉H₇NOFeCl₃ (cpx 4) (R=2,6-iPr₂C₆H₃) were synthesized. These ligands and the complexes were characterized by ¹H-NMR, ¹³C-NMR, FT-IR, UV-VIS and elemental analysis. 1-Hexene polymerization was performed with iron catalysts in the presence of methylaluminoxane (MAO) or boron compound, [Ph3C][C₆F₅)₄] and[PhMe₂NH][B(C₆F₅)₄] as cocatalyst. Parameters influencing the catalytic activity, such as amount of catalyst, amount of cocatalyst, Al/Fe mole ratio, polymerization time (tp), polymerization temperature (Tp), solvent and type of alkylating agent were investigated. Only cpx 1a and cpx 2b are found active. Dimer, trimer, pentamer and hexamer products from both complexes were characterized by FT-IR, ¹³C-NMR and GC-MS. For comparison, polymerization using metallocene catalyst, rac-Et(Ind) ₂ZrCl₂ was performed. The activity of 510 kg of polymer/mol catalyst was obtained. The polymer was characterized by FT-IR, ¹³C-NMR, ¹H-NMR, DSC and GPC to be isotactic poly (l-hexene) with molecular weight of 48,600.