Metallocene catalysts for olefin polymerization

Deffieux A, Cramail H, Radharkrishnen K, Pedeutour JN (2001) Reactivity of metallocene catalysts for olefin polymerization influence of activator nature and structure. Macromol Rapid Commun 22 1095-1123... 

Chien JCW, Llinas GH, Rausch MD, Lin YG, Winter HH, Atwood JL, Bott SG (1992) Metallocene catalysts for olefin polymerizations. XXIV. Stereoblock propylene polymerization catalyzed by rac-anri -ethylidene(l-T 5-tetramethylcyclopentadienyl)(l-r 5-indenyl) dimethyltitanium A two-state propagation. J Polym Sci A 30 2601-2617... 

Brookhart and coworkers [1] have recently developed Ni(II) and Pd(II) bis-imine based catalysts of the type (ArN=C(R)-C(R)=NAr)M-CH3+ (la of Figure 1) that are promising alternatives to both Ziegler-Natta systems and metallocene catalysts for olefin polymerization. Traditionally, such late metal catalysts are found to produce dimers or extremely low molecular weight oligomers due to the favorability of the P-elimination chain termination process [2],... 

Fig. 6 Typical metallocene catalysts for olefin polymerization containing a C2-symmetric ligand (left) and a Cs-symmetric ligand (right)...

Further evidence for the existence of cationic centers is given by the activation of metallocene catalysts for olefin polymerization by the use of anionic counterions such as tetraphenylborate (CeFIs B-, carborane (C2B9H12), or fluorinated borate. The use of (CgF5)4B counterions by Hlatky et al. (83), Sishta et al. (84), and Zambelli et al. (85) leads to highly active metallocene catalysts, which are formed by the reaction of a dealkylated zirconocene with dimethylaniliniumtetra(/us,-perfluorophenyl)borate ... 

Kaminsky, W., Metallocene catalysts for olefin polymerization, in Science and Technology in Catalysis 1998 (V. Dragutan and R. Streck, Eds.), p. 3. Elsevier, Amsterdam, 1999. 

Another combination catalyst that includes a Lewis acid component is Cp2MCl2/2n-BuLi/B(C6F5)3.60-61 Interest in such systems came about as a consequence of the successful use of well-characterized homogeneous cationic and cation-like Group 4 and actinide metallocene catalysts for olefin polymerization.62 63... 

The Heterogenization of Homogeneous Metallocene Catalysts for Olefin Polymerization... 

Suzuki and Suga reported the use of clays as solid acids to support and activate metallocene catalysts for olefin polymerization. They were able to use much less alkylaluminmn cocatalyst relative to solution polymerization conditions. The clays were slurried with AlMeg in toluene, then treated with a solution containing zirconocene dichloride, II, and AIMeg. The metallocenium cation was presumed formed via abstraction of chloride and/or methyl ligands by acidic sites on the surface of the clay, and the low basicity of the clay smface was proposed to stabilize the coordinatively unsaturated cation. Propylene was copolymerized with 250 psi ethylene at 70°C. For acid-treated KIO montmorillonite, an activity of 3300 X 10 kg polymer/(g Zr h) was obtained. Catalysts based on vermiculite, kaolin, and synthetic hectorite all showed lower but still appreciable activities. In this brief report, the Al/Zr ratio was not specified, and the clay dispersion was not reported. 

Suzuki, T. and Suga, Y. 1997. Solid acid supported metallocene catalysts for olefin polymerization. Polymer Preprints 38 207-208. 

Group NIB and f-BIOCk Metallocenes. The need for expensive cocatalysts has always hampered the development of metallocene catalysts for olefin polymerization. It was recognized early on that substitution of the Group IVB metal with a lanthanide or Group IIIB element in the -1-3, state would represent a cocatalyst-free analogue of the Kaminsky system. Active catalysts are indeed obtained from bis-Cp lanthanocenes and yttrium- and scandium-based congeners. The lutetium dimer 29 has an activity of >7 kg/mmol(Lu)/h/atm for ethylene polymerization in cyclohexane (95). (This remarkable compound can also break the C—H bonds of alkanes.)... 

Chien, J. C. W. Elinas, G. H. Rausch, M. D. Lin, Y. G Winter, H. H. Atwood, J. L. Bott, S. G. J. Metallocene catalysts for olefin polymerization catalyzed by rac-[anft -ethylidene(l-r -tetramethylcyclopentadienyl)(l-r -indenyl)]dimethyltitanium A two-state propagation. XXIV. Stereoblock propylene polymerization. J. Polym. ScL, Part A Polym. Chem. 1992, 30, 2601-2617. 

Kaminsky W (1999) Metallocene catalysts for olefin polymerization. Stud Surf Sci Catal 121 3 Katayama K, Amano T, Nakamura N (1968) Structural formation during melt spinning process. Kolloid Z Z Polym 226 125... 

Razavi A (2004) Synthesis of hydrogenated metallocene catalyst for olefin polymerization and polyolefins prepared thereby. Patent WO 2004/078,798 A2 2004/0,916, Fina Technology... 

J. M. Canich, G. G. Hlatky, H. W. Turner, Aluminum-free monocyclopentadienyl metallocene catalysts for olefin polymerization. PCTAppl. 1992 WO 92-00333. 

Kaminsky, W. Highly active metallocene catalysts for olefin polymerization. J. Chem. Soc. Dalton Trans., 1413-1418 (1998). 

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