Triisobutylaluminum Research Articles

Ethene Co- and Terpolymerizations with TIBA-Protected Norbornenemethanol and TIBA-Protected Norbornenecarboxylic Acid Using Homogeneous Metallocene/MAO Catalyst Systems

Ethene copolymerizations were carried out with triisobutylaluminum (TIBA)-protected norbornenemethanol and norbornenecarboxylic acid, respectively, using homogeneous metallocene/MAO catalyst systems. Moreover, ethene terpolymerizations with both polar norbornene derivatives were investigated for the first time. The metallocenes utilized, such as iPr[CpInd]ZrCl2, iPr[(3-iPr-Cp)Ind]ZrCl2, and iPr[(3-tert-But-Cp)Ind]ZrCl2 contain ligand frameworks of various sterical demands. The incorporation of polar monomers into the polymer chain was determined by NMR spectroscopic investigations. Kinetic and analytical results of the polymerization experiments revealed increasing activities and a decreasing comonomer incorporation into the polymer chain with an increasing sterical demand of the metallocene ligand. Additionally, the TIBA-protected norbornenecarboxylic acid shows a lower incorporation rate into the copolymer chain in comparison with the TIBA-protected norbornenemethanol.

Improving the Performance of Heterogeneous Borane Cocatalysts by Pretreatment of the Silica Support with Alkylaluminum Compounds

The treatment of silica with alkylaluminum compounds, triisobutylaluminum (TIBA) and triethylaluminum (TEA), dramatically enhanced the cocatalytic performances of the [CPh 3 ] + [B(C 6 F 5 ) 3 -SiO 2 ] - . We measured the productivity and ethylene-consumption profiles for [CPh 3 ] + [B(C 6 F 5 ) 3 -SiO 2 ] - cocatalysts and Cp 2 ZrCl 2 / TIBA. Both of the treated cocatalyst systems improved the average molecular weight of the product when compared with the untreated cocatalyst system. The TIBA-treated cocatalyst provided a narrow molecular weight distribution while the TEA-treated cocatalyst system gave a broad distribution.

Investigations on ternary metallocene-based catalyst systems

The influence of the cocatalyst triisobutyl aluminium (TiBA) on the two step reaction of the ternary activation of the metallocene precursor Ph2C(CpFlu)ZrCl2 with TiBA and the activator N,N-dimethylanilinium-tetrakis(pentafluorophenyl)borat (DMAB) was investigated by means of NMR spectroscopy. More than 5 equivalents of TiBA are required for a total conversion of Ph2C(CpFlu)ZrCl2. The reaction exclusiveley leads to the monoalkyl complex Ph2C(CpFlu)ZrClBui, independent of the Al / Zr ratio. The reaction of the Ph2C(CpFlu)ZrCl2 / TiBA mixtures, using 10, 20 and 50 equivalents of TiBA with DMAB, generates two cationic metallocene species. Using 100 equivalents of TiBA exclusiveley leads to the formation of the cationic heterodinuclear metallocene complex [Ph2C(CpFlu)Zr-(μ-H)-(μ-C4H7)-AlBu2i]+. In no case was the degradation or complexation of [B(C6F5)4]− detected, whereas the direct reaction between TiBA and DMAB gives AlBui3−x(C6F5)x compounds. A mechanism was postulated to explain the formation of [Ph2C(CpFlu)Zr-(μ-H)-(μ-C4H7)-AlBui2]+. The catalyst system Ph2C(CpFlu)ZrCl2 / TiBA / DMAB was used for continuous high pressure polymerizations of ethylene at 150 MPa and 180°C. To investigate the influence of additional TiBA and triethyl aluminium (TEA) in the reactor, their concentrations were varied over a wide range. Highest productivities and molecular weights were obtained with low concentrations of TiBA in the reactor. Up to a concentration of 30 molppm Al in the reactor, unimodal polymers were formed with Mw / Mn between 2 and 3. With higher aluminium concentrations, the products formed contained small amounts of waxes. This was due to oligomerization catalyzed by the aluminium alkyl compounds. Using the Schulz-Zimm distribution all MWDs were analyzed with regard to the amount of waxes produced by ethylene oligomerization and with regard to the influence of chain transfer reactions to the aluminium. The rate constants of chain transfer to aluminium in relation to the rate constants of insertion of ethylene were estimated.

Influence of Aluminium Alkyl Compounds on the High-Pressure Polymerization of Ethylene with Ternary Metallocene-Based Catalysts. Investigation of Chain Transfer to the Aluminium

The influence of aluminium alkyl compounds on metallocene-catalyzed high pressure polymerizations of ethylene has been investigated at 150 MPa and 180°C in a continuously operated autoclave. The catalysts were based on the metallocenes bis(cyclopentadienyl)zirconium dichloride (Cp2ZrCl2) and diphenylmethylene (cyclopentadienylfluorenyl)zirconium dichloride (Ph2C-(CpFlu)ZrCl2), which were preactivated outside the reactor with triisobutylaluminium (TiBA) and N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (DMAP, [PhNHMe2][B(C6F5)4]). The concentrations of triisobutylaluminium (TiBA) and triethylaluminium (TEA) in the reactor were varied over a wide range, using a separate dosing for these two aluminium alkyl compounds. Productivity and polymer properties strongly depended on the type and the concentration of the aluminium alkyl compound used. Highest productivities and molecular weights were obtained with low concentrations of TiBA in the reactor. Up to a concentration of 30 molppm Al in the reactor, unimodal polymers were formed with M̄w/M̄n between 2 and 3. With higher aluminium concentrations the products formed contained small amounts of waxes, due to oligomerization catalyzed by the aluminium alkyl compounds. The molecular weight distributions (MWDs) of these products could be described as a superimposition of two Schulz-Zimm distributions. All MWDs were analyzed with regard to the amount of waxes produced by ethylene oligomerization and with regard to the influence of chain transfer reactions to the aluminium. The rate constants of chain transfer to aluminium, in relation to the rate constants of insertion of ethylene, were estimated.

Influence of Aluminium Alkyl Compounds on the High-Pressure Polymerization of Ethylene with Ternary Metallocene-Based Catalysts. Investigation of Chain Transfer to the Aluminium

The influence of aluminium alkyl compounds on metallocene-catalyzed high pressure polymerizations of ethylene has been investigated at 150 MPa and 180°C in a continuously operated autoclave. The catalysts were based on the metallocenes bis(cyclopentadienyl)zirconium dichloride (Cp2ZrCl2) and diphenylmethylene (cyclopentadienylfluorenyl)zirconium dichloride (Ph2C-(CpFlu)ZrCl2), which were preactivated outside the reactor with triisobutylaluminium (TiBA) and N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (DMAP, [PhNHMe2][B(C6F5)4]). The concentrations of triisobutylaluminium (TiBA) and triethylaluminium (TEA) in the reactor were varied over a wide range, using a separate dosing for these two aluminium alkyl compounds. Productivity and polymer properties strongly depended on the type and the concentration of the aluminium alkyl compound used. Highest productivities and molecular weights were obtained with low concentrations of TiBA in the reactor. Up to a concentration of 30 molppm Al in the reactor, unimodal polymers were formed with Mw/Mn between 2 and 3. With higher aluminium concentrations the products formed contained small amounts of waxes, due to oligomerization catalyzed by the aluminium alkyl compounds. The molecular weight distributions (MWDs) of these products could be described as a superimposition of two Schulz-Zimm distributions. All MWDs were analyzed with regard to the amount of waxes produced by ethylene oligomerization and with regard to the influence of chain transfer reactions to the aluminium. The rate constants of chain transfer to aluminium, in relation to the rate constants of insertion of ethylene, were estimated.

Ethylene Polymerization with “Constrained-Geometry” Titanium Catalysts over Borate-Modified Silica Supports

Two different mesoporous silica materials, Sylopol® 948 and MPS5, were used as substrates for the preparation of silica-bound trityl tris(pentafluorophenyl)- borate activators. The borate-modified silica supports, B- Sylopol and B-MPS5, were characterized by solid-state NMR spectroscopy and ICP mass spectrometry, and applied as activators for slurry polymerization of ethylene using constrained-geometry titanium complexes of the formula Ti(η 5 :η 1 -C 5 Me 4 SiMe 2 NR)X 2 (R = Me, i Pr, t Bu; X = Me, Bz, Cl) in the presence of triisobutylaluminium (TIBA). The activity of the B-Sylopol system was higher than that of the corresponding homogeneous catalysts Ti(η 5 :η 1 -C 5 Me 4 SiMe 2 NR)X 2 /Ph 3 C + [B(C 6 F 5 ) 4 ] - , whereas that of the B-MPS5 system was lower. These supported catalysts produced polyethylenes with higher molecular weights (M w in the range of 10 6 ), narrower molecular weight distributions (M w /M n = 1.5-2.3) and higher bulk densities (up to 0.4 g/cm 3 ) compared to those of polyethylenes obtained with the homogeneous system. The resulting polyethylenes were found to replicate the shapes of the supported borate activators. Fine polyethylene particles due to the cracking of the support were observed with the B-Sylopol system, while well-shaped polyethylene spheres were formed with the B-MPS5 system.

Polymerization of methyl methacrylate with ethylene bridged heterodinuclear metallocene of samarium and titanium

A novel heterodinuclear catalyst, ethylene bridged samarocene and titanocene chloride (Sm–Ti), was used both as a single component catalyst (cat.) and also by activation with triisobutyl aluminum (TIBA) to polymerize methyl methacrylate (MMA). The binary catalyst demonstrated higher activity than the single component, but the molecular weight of the resultant PMMA is lower. Ultrahigh molecular weight PMMA (1.5×10 6) was obtained at an attractive conversion (87%) without any cocatalyst. The effects of polymerization parameters, such as temperature, time, molar ratios of Al( i-Bu) 3/cat. and MMA/cat., were studied in detail. The results showed that the catalytic activity had a rather different dependence on the polymerization temperature with/without TIBA. High molecular weight PMMA was much more easily prepared in a bulk system than in toluene solution. The polymer yielded with about 65% syndiotacticity by 1 H NMR and 75% by IR spectroscopy, but its stereoregularity did not change too much with polymerization temperature and the concentration of TIBA.

New highly active and selective Et oligomerization catalysts based on cationic diamide zirconium complexes

Group 4 complexes based on the diamide ligand, [Me3CN(SiMe2)2NCMe3]2−, have been investigated as possible catalysts for olefin conversions. The dialkyl complexes, (Me2SiNCMe3)2ZrR2 (R = CH2Ph, Me), were converted into zwitterionic (X-ray: {Me2SiNCMe3}2Zr(η1-Bz){ηn-BzB(C6F5)3}), or cationic mono-alkyl compounds by reaction with B(C6F5)3 or borate reagents. These electrophilic species catalyzed ethylene oligomerization, affording highly linear alpha-olefins under mild conditions (C6 fraction > 99.5% 1-hexene at 50°C, 6 bar). The highest activities (290 Kg/g Zr.h) were obtained in toluene solvent using tri-iso-butylaluminium (TIBA) as scavenger. The catalyst exhibited activity decay in alkane solvent, which was countered by replacement of TIBA by more crowded trialkylaluminium scavengers or branched alkylaluminoxane scavengers. The product consisted primarily of linear alpha-olefins (LAO) with low levels of remote-branched AO's. These are formed by successive insertion of higher olefin and one or more ethylenes in a growing chain, followed by chain transfer.

Copolymerization of ethylene and 1-hexene with Et(Ind)2ZrCl2 in hexane

Copolymerizations of ethylene and 1-hexene were carried out in hexane at 60°C by using ethylenebis(indenyl)zirconium dichloride as catalyst and methylaluminoxane (MAO) as cocatalyst in presence of triisobutylaluminum (TIBA). The influence of the alkylaluminum concentration and AlTOTAL/Zr molar ratio on the catalyst activity and comonomer incorporation are evaluated. Increasing the TIBA concentration, the MAO solubility augments in the polymerization milieu, as well as the catalyst activity and the comonomer incorporation. Increasing the AlTOTAL/Zr molar ratio, catalyst activity becomes higher, while comonomer incorporation remained constant at around 8wt% for molar ratios between 0 and 5000. For AlTOTAL/Zr molar ratios higher than 5,000 comonomer incorporation increased gradually. Under the same experimental conditions dimethylsilylbis(indenyl)zirconium dichloride showed higher thermal stability and led to higher comonomer incorporation.

Triisobutylaluminum as cocatalyst for zirconocenes. II. Triisobutylaluminum as a component of a cocatalyst system and as an effective cocatalyst for olefin polymerization derived from dimethylated zirconocenes

AbstractAn investigation of the catalytic behavior of the dimethylated zirconocenes Me2SiCp*NtBuZrMe2 [Cp* = C5(CH3)4; 1Me], Me2SiCp2ZrMe2 (2Me), Cp2ZrMe2 (3Me), Ind2ZrMe2 (4Me), Me2SiInd2ZrMe2 (5Me), Et(2‐MeInd)2ZrMe2 (6Me), and Me2Si(2‐MeInd)2ZrMe2 (7Me) with the combined activator triisobutylaluminum (TIBA)/CPh3B(C6F5)4 (Al/Zr = 250; B/Zr = 1) in ethylene polymerizations at increased monomer pressures (5–11 bar, 30 °C) was carried out. Sterically opened zirconocenes in ternary catalysts gave rise to active species effective in the formation of low molecular weight polyethylenes (PEs). These active species tended to increase the PE molecular weight [1Me (2100) < 2Me (20,000) < 5Me (89,000) < 3Me (94,500)] under similar conditions. PE obtained with 4Me showed a bimodal gel permeation chromatography curve with a 64% peak area [weight‐average molecular weight (Mw) = 43,000] and a 36% peak area (Mw = 255,000). The increase in sterical demands from the zirconocenes was also demonstrated by the reduction of the chain transfer to monomer, the reinsertion of vinyl‐ended PE chains, and their ability for isomerization. These reactions were most pronounced for the zirconocenes 1Me and 2Me. The active species responsible for the formation of low molecular weight PEs deactivated quickly. The zirconocenes 6Me, 7Me, and (2‐PhInd)2ZrMe2 (8Me) bearing substituent at the 2‐position of the indenyl ring was activated with TIBA alone, yielding active species effective in ethylene and propylene polymerizations. PEs formed with 6Me–8Me complexes activated with TIBA had high molecular weights. An increase in the Al/Zr ratio in the catalytic system 8Me/TIBA from 50 to 300 led to an enhancement of the molecular weight of polypropylene (PP) samples from oligomeric products to an viscosity‐average molecular weight of 220,000. The increase in the molecular weights of PPs with an increase in the propylene concentration was also observed. An analysis of the catalytic performance of the 8Me/TIBA system showed first‐order dependency of the initial polymerization rates on the TIBA concentration and close to second‐order dependency on propylene. The second‐order dependency on the monomer concentration is explained in terms of the monomer participation in the initiation step of the polymerization reaction. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1915–1930, 2001

Triisobutylaluminum as cocatalyst for zirconocenes. I. Sterically opened zirconocene/triisobutylaluminum/perfluorophenylborate as highly effective ternary catalytic system for synthesis of low molecular weight polyethylenes

AbstractEthylene polymerizations with catalytic systems Me2SiCp*NtBuZrX2 (1) [Cp* = C5(CH3)4; X = Cl (1Cl), Me (1Me)], triisobutylaluminum (TIBA), perfluorophenylborate CatB(C6F5)4 [Cat = CPh3 (3), Me2NHPh (4)], or Me2SiCp2ZrX2 [X = Cl (2Cl), Me (2Me)]/TIBA/3 (4) were performed within a wide range of ethylene pressures of different Al/Zr ratios, and Zr/B = 1. Catalytic systems 1Cl(2Cl)/TIBA/3 led to the formation of very high linear molecular weight polyethylene (PE) of Mη ∼2,000,000 with low activity. The replacement of both chlorine ligands in the precatalyst for the methyl ones led to the formation of active species producing low molecular weight PE with high activity. Chain transfer to ethylene was shown to be the main reaction controlling PE chain propagation: kp/ktr ∼20–30 for 1Me/TIBA/3 and kp/ktr ∼350–500 for 2Me/TIBA/3. It was suggested that TIBA was present in the active center first in the form of a neutral heterobimetallic Zr–Al bridged complex followed by the formation of a partially polarized Zr–Al(Cl)R2 (R = iBu) or an unreactive Zr–AlR3 cationic complex by abstraction of the alkyl ligand under the action of borate. It was concluded that AlR3 from the latter cationic complex may be easily reversibly replaced under the specific coordination of ethylene or accumulated α‐olefin, giving rise to highly labile and sterically accessible cationic species. Experiments on ethylene polymerization with the catalytic systems 1Cl(1Me)/TIBA/3/Ph2NH, 1Cl(1Me)/TIBA/4, 2Cl(2Me)/TIBA/3/Ph2NH, and 2Cl(2Me)/TIBA/4 were performed to confirm the suggestion. Catalytic systems derived from dichloride complexes in the presence of a σ‐donor substrate also produced low molecular weight PEs with molecular weight characteristics similar to those of products obtained with the dimethylated precatalysts. The specific feature of active species derived from 2Me complexes to isomerize coordinated α‐olefin into trans‐vinylene polymer chains was also revealed. The catalytic behavior of the ternary catalytic system based on 2Me relative to 2Me or 2Cl precatalysts activated with polymethylaluminoxane at different Al/Zr ratios was compared. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1901–1914, 2001

Extremely active polymerizations of propene by bisindenylzirconocenes and tetra(pentafluorophenyl)-borate

The homogeneous homopolymerization of propene was conducted with the two catalyst precursors Me 2Si(Ind) 2ZrBz 2 ( 1) and Me 2Si(2-Me-4-Ph-Ind) 2ZrBz 2 ( 2) and triphenylmethyltetrakis(pentafluorophenyl)borate [C(CH 3) 3][B(C 6F 5) 4] ( 3) as cocatalyst. After synthesizing the dibenzyl compounds from their dichloride derivatives the catalyst system ( 1)/( 3) was optimized in respect to the catalyst/cocatalyst ratio and the amount of tri(isobutyl) aluminum (TIBA). The polymerization behavior of the catalyst system ( 2)/( 3) is investigated using a central composite experimental design. In this design the dependence of the polymer properties on temperature, catalyst and monomer concentration are modeled. The dibenzyl compound ( 2) shows extremely high catalytic activities of 600 000 kg PP/mol Zr h mol p. The polymers produced with this catalyst exhibit very high melting points and molecular weights.

Novel monotitanocene and methylaluminoxane catalyst for syndiospecific polymerization of styrene

Syndiotactic polystyrene (sPS) was synthesized with a novel monotitanocene complex of η5-pentamethylcyclopentadienyltri-4-methoxyphenoxy titanium [Cp*Ti(OC6H4OCH3)3] activated by methylaluminoxane (MAO) in different polymerization media, including heptane, toluene, chlorobenzene, and neat styrene. In all cases bulk polymerization produced sPS with the highest activity and molecular weight. Solution polymerization produced much better activity in heptane than in the other solvents. Using a solvent with a higher dipole moment, such as chlorobenzene resulted in lower activity and syndiotacticity because of the stronger coordination of solvent with the Ti(III) active species, which controlled syndiospecific polymerization of styrene. With bulk polymerization at a higher polymerization temperature the Cp*Ti(OC6H4OCH3)3–MAO catalyst produced sPS with high catalytic activity and molecular weight. The external addition of triisobutylaluminum (TIBA) to the Cp*Ti(OC6H4OCH3)3–MAO system catalyzing styrene polymerization led to significant improvement of activity at a lower Al:Ti molar ratio, while the syndiotacticity and molecular weight of the yields were little affected. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1243–1248, 2001

Triisobutylaluminium mediated carbocyclisation of sugar derived spiroketals and ketosides

The carbocyclisation of sugar derived spiroketals and ketosides under the agency of triisobutylaluminium is presented. In addition, the synthetic usefulness of cyclooctenic product 21 , derived from the corresponding exo-glycal 20 , was shown by its transformation into conformationally locked l-idose analogues 22 and 23 .

Application of the triisobutylaluminum‐promoted reductive rearrangement to sucrose‐5‐enes

AbstractCarbohydrate‐based vinyl acetals (5‐hex‐enopyranosides) undergo reductive rearrangement with triisobutylaluminum (TIBAL) to afford highly functionalized cyclohexanes in which both the aglycon and anomeric stereochemistry are retained. Here, we report the first application of this process to the rearrangement of hex‐5‐enopyranosides of sucrose in which the interglycosidic oxygen atom of the vinyl acetal system links the anomeric centers of both monosaccharide units. The sucrose‐derived 5‐hex‐enopyranoside 1 undergoes smooth reductive rearrangement with TIBAL to afford the (1 → 2′) ether‐linked pseudo‐disaccharide 2 in 34% yield. The rearrangement is accompanied by some loss of stereochemical integrity at C‐2′ due to a competitive exo‐cleavage of the interglycosidic (O‐C2′) bond, hence diastereomers at C‐2′ are also obtained in 12% yield. The 4‐O‐allyl‐protected sucrose‐5‐ene 3 is similarly transformed into the corresponding (1 → 2′) ether‐linked pseudo‐disaccharide 4, illustrating the compatibility of the allyl group with the TIBAL reaction conditions.magnified image

Diimine nickel catalysis of ethylene copolymerization with polar cyclic monomers

ε-Caprolactam (CL) and tetrahydrofuran (THF) were copolymerized with ethylene (E) and terpolymerized with E and P (propylene) for the first time made possible using the late transition metal catalyst precursor [bis(N,N ′-dimesitylimino)acenaphthene]dibromonickel activated by methylaluminoxane (MAO). The polar cyclic monomers need to be pretreated with an equimolar quantity of AlR3 as modifier. Triisobutylaluminium (TIBA) was found to be the preferred modifier for CL, whereas trimethylaluminium (TMA) was the preferred modifier for THF. Copolymerization of CL and E occurs at high activity of 1 to 10×106 g/(mol Ni×[E]×h); it is very much slower for THF and E. Characterizations by FTIR, DSC, mechanical properties and elemental analysis for C, H and N showed that novel high molecular weight (1.5 to 2.0×105) copolymers of E and CL were prepared containing about 14 CL units per chain. Terpolymerization of E, P and CL were also achieved for the first time. In contrast, the copolymerization involving THF was slower, favored by TMA pretreatment over TIBA and elevated temperature. A mechanism for E and CL copolymerization is proposed.

Gas-phase polymerization of 1,3-butadiene with supported half-sandwich-titanium-complexes

Using half-sandwich-titanium-complexes polybutadiene (BR) can be produced with a particular microstructure of about 81% cis, 18% 1,2, and 1% trans units. A stirred bed reactor and a fluidized bed reactor were constructed for gas-phase polymerization of 1,3-butadiene by cyclopentadienyltrichlorotitanium (CpTiCl3) on MAO (methylaluminoxane) impregnated silica (MAO/SiO2). The major determinant of polymerization activity and molecular weight is the AlMAO/Ti-ratio on the carrier. Polymerization activity increases to 14 500 kg BR/(mol Ti*h) with a molecular weight of 1.9×106 g/mol and the catalyst becomes noticeably more stable. Activity further increases when the CpTiCl3 catalyst is prealkylated with small quantities of TIBA (triisobutylaluminium). Systematic methodological experimentation of the heterogenization suggests that a Ti(III)-species is responsible for polymerization. The gas-phase polymerization of 1,3-butadiene reveals a rate of polymerization which is considerably greater than the equivalent rate in the homogeneous system. The polymers all have similar characteristics, pointing to the same active species. The microstructure of the polybutadiene produced was investigated by spectroscopic measurements and by hydration; a preference to block structures of 1,2-units could not be established.

Ring-opening polymerization of styrene oxide with rare earth coordination catalysts

Ring-opening polymerization of styrene oxide was successfully carried out by using new rare earth catalytic systems for the first time. It has been found that trinary rare earth coordination catalysts composed of neodymium 2-ethylhexyl phosphonate or calix[6]arene–neodymium, tri-isobutyl aluminum and 2-ethylhexyl phosphonate are effective catalysts for the ring-opening polymerization of styrene oxide. The dependence of polymerization on molar ratio of catalyst components (Al/Nd), solvent, polymerization temperature and time has been investigated. The polymers were characterized by IR, 1H-NMR, 13C-NMR and GPC.

Synthesis and application in high-pressure polymerization of a titanium complex with a linked cyclopentadienyl-phenoxide ligand

The ansa half-sandwich complex [η 5:η 1-C 5H 4-C(CH 3) 2-2-C 6H 4O]TiCl 2 ( 1) has been prepared using two different ways, a ‘one-pot’ synthesis and a synthesis via thermolysis of the Ti trichloride precursor [η 5-C 5H 4-C(CH 3) 2-2-C 6H 4OCH 3]TiCl 3 ( 3). When activated with methylaluminoxane ( 4) or the cocatalyst system triisobutyl aluminum/[Me 2PhNH] +[B(C 6F 5) 4] − ( 5), complex 1 could be used as a catalyst in high-pressure, high-temperature polymerization. The productivity of the catalyst system 1/ 4 in high-pressure polymerization of ethene is 400 t polymer mol −1 Ti, while the productivity of catalyst system 1/ 5 is only 6 t polymer mol −1 Ti. In ethene/1-hexene copolymerizations productivity and molecular weights decrease with increasing 1-hexene in the feed. The polymerization results were discussed and compared to results of high-pressure polymerization with the catalyst system Me 2Si[IndH 4] 2ZrCl 2/ 4.

Synthesis of Novel Hindered Amine Light Stabilizers (HALS) and Their Copolymerization with Ethylene or Propylene over Both Soluble and Supported Metallocene Catalyst Systems

Novel polymerizable hindered amine light stabilizers (HALS) such 1-(but-3-enyl)-2,2,6,6-tetramethylpiperidine (1), 1-(undec-10-enyl)-2,2,6,6-tetramethylpiperidine (2), 4-(but-3-enyl)-1,2,2,6,6-pentamethyl-3,4-dehydropiperidine (3), 2-(but-3-enyl)-2,6,6-trimethylpiperidine (4), 4-(but-3-enyl)-1,2,2,6,6-pentamethyl-4-piperidyl ether (5), 4-(undec-10-enylamide)-1,2,2,6,6-pentamethylpiperidine (6), 4-((N-n-butyl)-undec-10-enylamide)-1,2,2,6,6-pentamethylpiperidine (7), and bis(N-n-butyl-N-2,2,6,6-tetramethylpiperidine)-N-n-butyl-N-allyltriazine (8) were synthesized. All the aforementioned HALS monomers except for 5 and 8 were successfully copolymerized in fair to high yields with ethylene or propylene over eight different group 4 metallocene catalysts using methylalumoxane (MAO) as cocatalyst. Copolymerizations were also performed over a supported metallocene/SiO2/MAO/triisobutylaluminum(TIBA) catalyst system. The silica-supported metallocene catalyst system readily promoted copolymerization of the sterically...