Polymerization and Copolymerization Reactions of Light Alkenes with Postmetallocene Catalysts Containing Titanium Complexes with Bidentate Pinacol Ligands

Abstract

Two Ti complexes with bidentate ligands derived from pinacol and perfluoropinacol and activated with a binary Al(C 2 H 5 ) 2 Cl -Mg(C 4 H 9 ) 2 cocatalyst are efficient catalysts for polymerization of lightest alkenes, ethylene and propylene, and for their copolymerization. They produce linear polyethylene of moderate molecular weight and essentially atactic amorphous polypropylene. Ethylene/propylene copolymers prepared with these catalysts are compositionally uniform resins with a very low crystallinity degree which can be used as synthetic EPM rubbers.

New Titanium(IV)-Alkoxide Complexes Bearing Bidentate OO Ligand with the Camphyl Linker as Catalysts for High-Temperature Ethylene Polymerization and Ethylene/1-Octene Copolymerization

“…Compared to previously obtained titanium complexes with flexible aliphatic diolate ligands [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ], complexes 1–4 with a rigid camphane framework were characterized by increased thermal stability. Complex 2 with an increased steric load at hydroxyl groups was able to produce UHMWPE even at a temperature of 70 °C.…”

“…Previously, we reported on the ability of various titanium(IV)–diolate complexes VII-X [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ], including those with additional heteroatoms [ 23 , 24 , 25 , 26 , 27 ] ( Chart 1 ), to catalyze the (co)polymerization of ethylene in the presence of such Al/Mg activators. This group of postmetallocene precatalysts is poorly studied, which is most likely due to the specifics of their activation: in the presence of trialkylaluminum derivatives, alkylaluminum chlorides, or alkylalumoxanes (traditional activators in Ziegler–Natta catalysis), and the activity of these systems is low or does not manifest itself at all.…”

“…An essential point limiting the possibility of the industrial implementation of this group of catalysts is their low thermal stability. As a rule, the maximum productivity of such systems is achieved at a temperature of 30 °C [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ]; an increase in the polymerization temperature to 50–80 °C is accompanied by deactivation and a significant reduction in the polymer’s molecular weight. The aim of this work is the structural modification of the ligand environment of the metal, aimed at increasing the thermal stability of the considered precatalysts.…”

Alkene polymerization reactions with catalysts based on acetylacetonate complexes of vanadium and titanium: effect of cocatalyst

“…The resolution results were analyzed assuming that the soluble fraction contained a small amount of low‐MW isotactic material and the insoluble fraction contained a small amount of high‐MW atactic material. The component separation procedure was described in detail earlier 18,19 . Figure 7(A) shows GPC curves of the total PP product and those of its atactic and partially isotactic components drawn in scale ( ca 91 and 9%).…”

“…Earlier, we showed that binary combinations of two organometallic compounds, AlR 2 Cl (R = C 2 H 5 or i‐C 4 H 9 ) and MgR′ 2 (R′ = n ‐C 4 H 9 and i‐C 4 H 9 ), when used at an [Al]:[Mg] molar ratio of >2, are universal activators for various types of transition metal polymerization catalysts, including TiCl 4 , 18,19 common Ti 3+ ‐ and Ti 4+ ‐based heterogeneous and supported catalysts, 20 Ti(OR) 4 , 21,22 metallocene complexes 23 and numerous post‐metallocene catalysts 20,23–28 …”