Ulrich Weingarten

Ethene/propene copolymerisation by [Me2C(3‐RCp)(Flu)]ZrCl2/MAO (R = H, Me, isoPr, tertBu)

Ethene/propene copolymerisations were carried out at 30°C and 60°C using four different metallocenes [Me2C(3-RCp)(Flu)]ZrCl 2 (R = H, Me, iso Pr, tert Bu). With increasing size of the substituent distinct changes in the copolymerisation behaviour and polymer microstructure were observed. A copolymerisation model taking into account the heterotopic nature of the metallocenes has been developed which fits the experimental triad distributions obtained. It is concluded that copolymerisation proceeds via chain migratory insertion for R = H and Me whereas a retention mechanism is found for R = tert Bu. For R = iso Pr especially at 60 °C a defective alternating mechanism seems to be operative.

EP(D)M-synthesis with highly active homogeneous and heterogeneous metallocene/MAO-catalysts

Abstract Copolymerizations of ethene and propene were carried out either with the soluble catalyst systems dimethylsilylbis(2-methyl-4-phenylindenyl)zirconiumdichloride/methylaluminoxane (MAO) (1), isopropylidenecyclopentadienylfluorenylzirconiumdichloride/MAO (2) and isopropylidene(3-methylcyclopentadienyl)fluorenylzirconiumdichloride/MAO (3) in toluene or with the supported metallocenes (1)/SiO 2 , (2)/SiO 2 and (3)/SiO 2 in the gas phase. Furthermore, terpolymerizations of ethene, propene and 5-ethylidene-2-norbornene (ENB) were performed with the homogeneous system (3) and with the heterogeneous system (3)/SiO 2 in the gas phase. The physical and chemical properties of the resulting polymers were compared in order to examine the behavior of the metallocenes when supported. In general, they work in much the same way as their soluble counterparts and the synthesis of EP(D)M co(ter)polymers with the above mentioned metallocenes can easily be transfered to gas phase processes.

Synthesis, characterization, and catalytic properties of bis[alkylindenyl]-, bis[alkenylindenyl]- and [alkenylindenyl(cyclopentadienyl)]zirconium dichloride complexes

Abstract 4,7-Dimethylindenyl lithium or 2,4,7-trimethylindenyl lithium reacts with 1-bromobutane, 1-chloro-2-propene, or 1-bromo-3-methyl-2-butene to give 3-butyl-4,7-dimethyl-1 H -indene ( 1 ), 3-(2-propene-1-yl)-2,4,7-trimethyl-1 H -indene ( 2 ), or 3-(3-methyl-2-butene-1-yl)-2,4,7-trimethyl-1 H -indene ( 3 ), respectively. Deprotonation of 1 – 3 with n -butyl lithium yields the lithium salts 1a – 3a . The reactions of 1a – 3a and of [1-(4-pentene-1-yl)indenyl]lithium ( 4a ) with zirconiumtetrachloride produce the complexes bis[1-butyl-4,7-dimethylindenyl]- ( 1b ), bis[1-(2-propene-1-yl)-2,4,7-trimethyl-indenyl]- ( 2b ), bis[1-(3-methyl-2-butene-1-yl)-2,4,7-trimethylindenyl]- ( 3b ) or bis[1-(4-pentene-1-yl)indenyl]zirconium dichloride ( 4b ). The reaction of cyclopentadienylzirconium trichloride with [2-(3-butene-1-yl)-4,7-dimethylindenyl]lithium or [2-(4-pentene-1-yl)-4,7-dimethylindenyl]lithium affords the mixed complexes [2-(3-butene-1-yl)-4,7-dimethylindenyl(cyclopentadienyl)]zirconium dichloride ( 5c ) or [2-(4-pentene-1-yl)-4,7-dimethylindenyl(cyclopentadienyl)]zirconium dichloride ( 6c ). All new compounds were characterized by elemental analysis, 1 H- and 13 C{ 1 H}-NMR spectroscopy as well as by mass spectrometry. In addition, single-crystal X-ray structural analysis was done for 3b . The complexes 1b – 4b , 5c , and 6c were tested as catalysts for the homopolymerization and copolymerization of ethene and propene and the results were compared to those of analogous compounds.

Comparison of the Polymerization of Propene by Homogeneous and Heterogeneous Metallocene/MAO‐Catalysts under Different Polymerization Conditions

Propene was polymerized using rac-dimethylsilylbis(2-methyl-4-(1-naphtyl)indenyl)zirconium dichloride (rac-[Me2Si(2-Me-4-(1-Naphtyl)Ind)2]ZrCl2) under six sets of conditions: in toluene solution, bulk, toluene slurry, bulk with the supported metallocene, a stirred bed with polyethene and a stirred bed with NaCl. The first two procedures were carried out with methylaluminoxane (MAO) as cocatalyst, the latter four were performed with methylaluminoxane supported on silicagel (MAO/SiO2) as activator. The differences between the procedures employed were examined by comparison of the polymer properties of the resulting products and of the activities at different temperatures. The polymerization procedure has a significant influence on the products. The polypropenes obtained with the homogeneous catalyst systems have generally high melting points and molar masses and exhibit very high activities. The heterogeneous analogues, on the other hand, gain enhanced stability by supporting, even at higher temperatures.

Synthesis and characterization of 1- and 2-(ω-alken-1-yl)indenes, their lithium salts and dichlorozirconium(IV) complexes

A series of new 1-, 2-, and multi-substituted indenes has been synthesized and characterized. The reaction of indenyl lithium or 4,7-dimethylindenyl lithium with alkenyl bromides yielded a mixture of 1- and 3-allylindene ( 1 ), 3-(3-buten-1-yl)indene ( 2 ), 3-(4-penten-1-yl)indene ( 3 ), 3-allyl-4,7-dimethylindene ( 4 ), 3-(3-buten-1-yl)-4,7-dimethylindene ( 5 ), as well as 3-(4-penten-1-yl)-4,7-dimethylindene ( 6 ). The 2-substituted indenes 2-allylindene ( 7 ), 2-(3-buten-1-yl)indene ( 8 ), 2-(4-penten-1-yl)indene ( 9 ), 2-allyl-4,7-dimethylindene ( 10 ), 2-(3-buten-1-yl)-4,7-dimethylindene ( 11 ), and 2-(4-penten-1-yl)-4,7-dimethylindene ( 12 ) were prepared by PdCl 2 (DPPF) or NiCl 2 (DPPE) catalyzed cross-coupling reactions of the appropriate Grignard reagents with 2-bromoindene or 2-bromo-4,7-dimethylindene. Alkenylation of 3-methylindenyl lithium and 2,4,7-trimethylindenyl lithium produced 1-(3-buten-1-yl)-3-methylindene ( 13 ) or 1-(3-buten-1-yl)-2,4,7-trimethylindene ( 14 ), respectively. The indene derivatives 1 – 14 react with n -butyl lithium in hexane yielding the corresponding lithium salts 1a – 14a . Zirconium tetrachloride reacts with 1a , 2a , 4a – 6a and 11a – 14a under formation of the corresponding bis(indenyl)zirconium dichloride complexes 1b , 2b , 4b – 6b and 11b – 14b . All compounds were characterized by elemental analysis, 1 H and 13 C{ 1 H}-NMR spectroscopy and mass spectrometry, 5b and 12b also by single crystal X-ray structural analysis. 1b , 4b – 6b and 11b – 13b are active catalysts for the polymerization of ethene and propene.

Ethene/styrene-copolymerizations with [Me2C(3-RCp)(Flu)]ZrCl2/MAO (R=H,Me,tertBu, cHex, Ph)

Abstract Two new C 1 -symmetric zirconocenes of the type [Me 2 C(3-RCp)(Flu)]ZrCl 2 bearing a phenyl (Ph) or a cyclohexyl (cHex) substituent on the cyclopentadienyl ring were synthesized. Copolymerizations of ethene and styrene were carried out using these catalysts and compared to the results obtained with the methyl- and tert butyl-substituted as well as with the unsubstituted system. By the introduction of the phenyl substituent both the activities and the molar masses could be increased whilst the styrene incorporation was comparable to that achieved with the unsubstituted system. In the case of the alkyl substituted systems (R=Me, tert Bu, cHex) the styrene incorporation is decreased drastically and molar masses and activities are also strongly effected.

Surface model for gas-phase polymerizations of ethylene and propylene using supported metallocene/methylalumoxane catalysts

In order to obtain more detailed information about supported metallocene/methylaluminoxane catalysts, two catalysts are supported onto a flat silicon wafer by spincoating impregnation. These model catalysts are characterized by SEM and EDX showing a film of metallocene catalyst dispersed inside the methylaluminoxane matrix, as well as regions of a localized increased concentration of the catalyst. Applying these model catalysts in a gas-phase polymerization reactor results in rather homogeneous films of polyethylene and polypropylene, respectively. In addition, crater-like and spherical polymer structures can be observed, probably formed by inhomogeneous catalyst distribution.

The influence of the polymerization process on the product properties of metallocene-polypropene

Metallocene based catalysts are excellent tools in the production of poly--olefins. The product properties of these catalysts can be tailor-made by controlling the microstructure as well as the molar mass and the thermal properties. Rac-[Me2Si(2-Me-4-(1-Naphtyl)Ind2]ZrCl2/MAO is a system that exhibits exceptional capabilities in respect to activity and isospecificity while producing polypropenes with high molar masses in the solution process.

Metallocene Catalyzed Alternating Copolymerization of Olefins

C1-symmetric metallocenes enable the production of alternating copolymers as well as that of blocky ones. A new model of copolymerization has been developed and applied to ethene/norbornene, ethene/propene and ethene/octene copolymerization. It is shown that the mechanism of polymerization depends on the catalysts structure, the monomer structure, and the temperature of polymerization.