Alkene polymerization, metallocene catalyzed

Landis and coworkers [140] have developed an active-site counting method based on H-labelling, for the metallocene-catalyzed alkene polymerization. After quenching the reaction by addition of methanol, the polymer is analyzed by NMR, which allows the quantification of Zr-alkyl sites. A typical NMR of quenched polymer is shown in Scheme 1.7 (label is found at terminal positions only). This technique has been applied to the polymerization of 1-hexene catalyzed by [Zr(rac-C2H4(l-indenyl)2)Me][MeB(QF5)3], 91. As shown in Scheme 1.7, there are two possible approaches ... 

Casey et al. have studied complex 98 as a model for intermediates in metallocene catalyzed alkene polymerization, by means of LSA [166]. 

Methylaluminoxane (MAO), sometimes referred to as polymethylaluminoxane (PMAO), currently gamers the most industrial interest of aU the alkylaluminoxanes owing to its activity as a cocatalyst for metallocene-catalyzed alkene polymerization (see Oligomerization Polymerization by... 

Regarding metallocene-based catalysts, several reports concerning the copolymerization of functionalized olefins with simple a-olefins have been published. In course of their extensive studies on the metallocene-catalyzed polymerization of aluminum-protected oxygen-containing monomers, Lofgren a al. also examined ester-functionalized olefins. " ° ° Decomposition reactions could be observed in the reaction of ester functionalities and MAO. ° For example, during the reaction of tert-butyl undecenoate with MAO, slow formation of alkene fragments can be observed by NMR spectroscopic... 

Ziegler-Natta polymerization of alkenes is an important industrial process for the manufacture of polyolefins. Although it originally involved the use of the triethylaluminum-TiCft complex as the catalysts, many other transition metal complexes and /-block compounds (lanthanides) also catalyze the polymerization of alkenes. Group IV metallocenes exhibit particularly outstanding properties. 

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