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  • 1
    Electronic Resource
    Electronic Resource
    (η5-Pentamethylcyclopentadienyl)trimethyltitanium as a precursor for the syndiospecific polymerization of styrene (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 8 (1994), S. 393-396 
    Details
    ISSN: 0268-2605
    Keywords: Polystyrene ; syndiotactic ; syndioselective ; MAO ; cationic catalysts ; trityl tetrakis(pentafluorophenyl)borate ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An equimolar mixture of Cp*Ti(CH3)3 (2) and Ph3C+[B(C6F5)4]- (1) forms a highly active and syndioselective catalyst for the polymerization of styrene, producing 96% syndiotactic polystyrene (PS) at an activity of 0.91 × 107 g PS (mol Ti)-1 (mol styrene)-1 h-1. Both activity and syndioselectivity can be increased using tri-isobutylaluminum (TIBA) to scavenge the system. ESR measurements indicate that the polymerization proceeds via titanium(IV) intermediates. Catalysts derived from 2/methylaluminoxane (MAO) as well as Cp*TiCl3/MAO also function as syndioselective styrene polymerization catalysts, but are less active than the ‘cationic’; system derived from 1 and 2.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590080413
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  • 2
    Electronic Resource
    Electronic Resource
    Low-temperature isospecific polymerization of propylene catalyzed by alkylzirconocene-type ‘cations’ (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 7 (1993), S. 71-74 
    Details
    ISSN: 0268-2605
    Keywords: Polypropylene ; polymerization ; isospecificity ; alkylzirconocene-type cations ; stereoselectivity ; MAO ; cationic catalysts ; trityl tetrakis(pentafluorophenyl)borate ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rac-ethylenebis(indenyl)methylzirconium ‘cation’ (1), generated from rac-Et(Ind)2ZrMe2 and Ph3CB(C6F5)4, has recently been shown to be exceedingly active and stereoselective in propylene polymerization. The ethyl analog (2) can be produced by an alternate, efficient route involving a reaction between rac-Et(Ind)2ZrCl2 and AlEt3 (TEA), followed by addition of Ph3CB(C6F5)4. The use of excess AlEt3 serves both to alkylate the zirconium complex as well as to scavenge the system. The propylene polymerization activity of the ‘cation’ 2 is about 7000 times greater than the activity of rac-Et(Ind)2ZrCl2/methylaluminoxane (MAO) at Tp=-20°C. The related catalyst system rac-Me2Si(Ind)2ZrCl2/TEA/Ph3CB(C6F5)4 (3) was found to produce 98.3% i-PP with Tm 156.3°C and an activity of 1.8 × 109 g PP {(mol Zr) [C3H6]h}-1.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590070109
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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