Terunori Fujita

FI Catalysts: A New Family of High Performance Catalysts for Olefin Polymerization

This paper reviews a new family of olefin polymerization catalysts. The catalysts, named FI catalysts, are based on non-symmetrical phenoxyimine chelate ligands combined with group 4 transition metals and were developed using “ligand-oriented catalyst design”. FI catalysts display very high ethylene polymerization activities under mild conditions. The highest activity exhibited by a zirconium FI catalyst reached an astonishing catalyst turnover frequency (TOF) of 64,900 s –1 atm –1, which is two orders of magnitude greater than that seen with Cp2ZrCl2 under the same conditions. In addition, titanium FI catalysts with fluorinated ligands promote exceptionally high-speed, living ethylene polymerization and can produce monodisperse high molecular weight polyethylenes (Mw/Mn 400,000) at 50 °C. The maximum TOF, 24,500 min –1 atm –1, is three orders of magnitude greater than those for known living ethylene polymerization catalysts. Moreover, the fluorinated FI catalysts promote stereospecific room-temperature living polymerization of propylene to provide highly syndiotactic monodisperse polypropylene (max. [rr] 98%). The versatility of the FI catalysts allows for the creation of new polymers which are difficult or impossible to prepare using group 4 metallocene catalysts. For example, it is possible to prepare low molecular weight (Mv∼103) polyethylene or poly(ethylene-co-propylene) with olefinic end groups, ultra-high molecular weight polyethylene or poly(ethylene-co-propylene), high molecular weight poly(1-hexene) with atactic structures including frequent regioerrors, monodisperse poly(ethylene-co-propylene) with various propylene contents, and a number of polyolefin block copolymers [e.g., polyethylene-b-poly(ethylene-co-propylene), syndiotactic polypropylene-b-poly(ethylene-co-propylene), polyethylene-b-poly(ethylene-co-propylene)-b-syndiotactic polypropylene]. These unique polymers are anticipated to possess novel material properties and uses.

Development and Application of FI Catalysts for Olefin Polymerization: Unique Catalysis and Distinctive Polymer Formation

Catalysts contribute to the efficient production of chemicals and materials in almost all processes in the chemical industry. The polyolefin industry is one prominent example of the importance of catalysts. The discovery of Ziegler-Natta catalysts in the 1950s resulted in the production of high-density polyethylenes (PEs) and isotactic polypropylenes (iPPs). Since then, further catalyst development has led to the production of a new series of polyolefins, including linear low-density PEs, amorphous ethylene/1-butene copolymers, ethylene/propylene/diene elastomers, and syndiotactic PPs (sPPs). Polyolefins are now the most important and the most produced synthetic polymers. This Account describes a family of next-generation olefin polymerization catalysts (FI catalysts) that are currently being used in the commercial production of value-added olefin-based materials. An FI catalyst is a heteroatom-coordinated early transition metal complex that combines a pair of nonsymmetric phenoxy-imine [O(-), N] chelating ligands with a group 4 transition metal. The catalytically active species derived from FI catalysts is highly electrophilic and can assume up to five isomeric structures based on the coordination of the phenoxy-imine ligand. In addition, the accessibility of the ligands of the FI catalysts and their amenability to modification offers an opportunity for the design of diverse catalytic structures. FI catalysts exhibit many unique chemical characteristics: precise control over chain transfers (including highly controlled living ethylene and propylene polymerizations), extremely high selectivity for ethylene, high functional group tolerance, MAO- and borate-free polymerization catalysis, significant morphology polymer formation, controlled multimodal behavior, high incorporation ability for higher alpha-olefins and norbornene, and highly syndiospecific and isospecific polymerizations of both propylene and styrene. These reactions also occur with very high catalyst efficiency. The reaction products include a wide variety of unique olefin-based materials, many of which were previously unavailable via other means of polymerization. We have produced selective vinyl- and Al-terminated PEs, ultrahigh molecular weight linear PEs, regio- and stereoirregular high molecular weight poly(higher alpha-olefin)s, ethylene- and propylene-based telechelic polymers, a wide array of polyolefinic block copolymers from ethylene, propylene, and higher alpha-olefins, and ultrafine noncoherent PE particles. FI catalysts are important from the organometallic, catalytic, and polymer science points of view, and the chemical industry is now using them for the production of value-added olefin-based materials. We anticipate that future research on FI catalysts will produce additional olefin-based materials with unique architectures and material properties and will offer scientists the chance to further study olefin polymerization catalysis and related reaction mechanisms.

Microstructure of Highly Syndiotactic “Living” Poly(propylene)s Produced from a Titanium Complex with Chelating Fluorine-Containing Phenoxyimine Ligands (an FI Catalyst)

Highly syndiotactic “living” poly(propylene)s were synthesized at 25°C using a bis[N-(3-tert-butylsalicylidene)-2,3,4,5,6-pentafluoroanilinato]titanium (IV) dichloride/MAO catalyst system, and microstructures of the polymer were analyzed by means of 13C NMR spectroscopy. The syndiotactic poly(propylene) contains isobutyl, isopentyl and propyl end groups, suggesting that the living polymerization of propylene was initiated via 1,2-insertion, followed by 2,1-insertion as the principal mode of polymerization. Pentad distribution analysis revealed that the syndiospecific polymerization proceeds under chain-end control.

Ethylene/Polar Monomer Copolymerization Behavior of Bis(phenoxy–imine)Ti Complexes: Formation of Polar Monomer Copolymers

Bis(phenoxy-imine) Ti complexes bearing a phenyl group ortho to the phenoxy-O can mediate the copolymerization of ethylene and 5-hexene-1-yl-acetate though they are group 4 transition metal catalysts.

A new titanium complex having two phenoxy-imine chelate ligands for ethylene polymerization

A new titanium complex having two phenoxy-imine chelate ligands, bis[N-(3-tert-butylsalicylidene)anilinato]titanium(IV)dichloride 1, was synthesized and its structure determined by X-ray analysis. Density functional theory (DFT) calculations and X-ray analysis suggest that complex 1, when activated, possesses two available cis-located sites needed for ethylene polymerization. Complex 1/methylaluminoxane (MAO) in toluene or heptane solvent displayed very high ethylene polymerization activities (2 280-4 150 (kg PE).(mol cat) -1 .h -1 ) with high molecular weight values (M v = 288 000- 881 000) at 25-75 °C under atmospheric pressure. The activity values displayed by complex 1/MAO are some of the highest values exhibited by any titanium complex with no cyclopentadienyl (Cp) ligand(s). Alternatively, complex 1/ i Bu 3 Al/Ph 3 CB(C 6 F 5 ) 4 in toluene solvent displayed high ethylene polymerization activities (190-670 (kg PE).(mol cat) -1 .h -1 ) with exceptionally high molecular weight values (M v = 3 920 000-5 860 000) at 25-75 °C under atmospheric pressure. The molecular weight values displayed by complex 1/ i Bu 3 Al/Ph 3 CB(C 6 F 5 ) 4 are some of the largest values displayed by homogeneous olefin polymerization catalysts including the group 4 metallocenes. The high potential of complex 1 for ethylene polymerization has therefore been demonstrated.

Polymerization of 1-hexene with bis[N-(3-tert-butylsalicylidene)phenylaminato]titanium(IV) dichloride using iBu3Al/Ph3CB(C6F5)4 as a cocatalyst

1-Hexene polymerization was investigated with bis:N-(3-tert-buty salicylidene)phenylamina-to]titanium(IV) dichloride (1) using Bu 3 Al/Ph 3 CB(C 6 F 5 ) as a cocatalyst. This catalyst system produced poly(1-hexene) having a high molecular weight (M a = 445000-884000. 0-60°C). 13 C NMR spectroscopy revealed that the high molecular weight poly(1-hexene) possesses an atactic structure with about 50 mol-% of regioregular units.

New olefin polymerization catalyst systems comprised of bis(phenoxy-imine) titanium complexes and MgCl2-based activators

Abstract MgCl 2 / i -butylaluminum 2-ethyl-1-hexoxide, i -Bu m Al(OR) n , prepared by the dealcoholysis of the MgCl 2 /2-ethyl-1-hexanol adduct with i -Bu 3 Al, was investigated as an activator for bis(phenoxy-imine)Ti complexes. The complexes with MgCl 2 / i -Bu m Al(OR) n displayed very high ethylene polymerization activities comparable to those obtained with methylalumoxane (MAO) activation. In addition, the activities obtained were comparable to or exceeded that found for the Cp 2 TiCl 2 /MAO catalyst system under identical conditions. Moreover, the catalyst systems produced narrow molecular weight distribution polyethylenes displaying good morphology. These are the first examples of MAO- or borate-free, highly active, single-site catalysts based on a transition metal complex and a MgCl 2 -based activator.

Substituted indenyl ring containing metallocene catalyst for propylene polymerization process

The novel transition metal catalyst of the invention is represented by the following formula (I): ##STR1## wherein M is a zirconium or hafnium; R1 is a hydrocarbon group of 2 to 6 carbon atoms, R2 is an aryl group of 6 to 16 carbon atoms; X1 and X2 are each a halogen atom; and Y is a divalent hydrocarbon group, a divalent silicon-containing group.

A Bis(phenoxy-imine)Zr Complex for Ultrahigh-Molecular-Weight Amorphous Ethylene/Propylene Copolymer

A new bis(phenoxy-imine)Zr complex has been developed. This complex in conjunction with i Bu 3 Al/ph 3 CB(C 6 F 5 ) 4 at 70°C produces ultrahigh-molecular-weight amorphous ethylene/propylene copolymer with a weight-average molecular weight of 10 200 000g/mol versus polystyrene standards, which represents the highest molecular weight known for linear, synthetic copolymers to date.

Synthesis of Telechelic Olefin Polymers via Catalyzed Chain Growth on Multinuclear Alkylene Zinc Compounds

Multinuclear alkylene zinc (MAZ) compounds of the type EtZn-(R″-Zn)n-Et (R″ = ethyl and propyl branched alkylene groups) were synthesized by a simple one-step procedure in nonpolar hydrocarbon solvents from α,ω-dienes (e.g., 1,7-octadiene or 1,9-decadiene) and diethylzinc using a bis(salicylaldiminato)Zr(IV) complex, [(2-methylcyclohexyl)N═CH(2-O-C6H3-3,5-di-tert-butyl)]2ZrMe2, as a catalyst. The MAZ serves as a divalent reversible chain-transfer agent for olefin polymerization, resulting in telechelic Zn-metalated polyolefins whose molecular weights are controllable over a wide range. The Zn-terminated telechelics serve as a polymer precursor for further reactions and can be converted into a variety of telechelic functionalized polyolefins in high yield.