Major commercial metallocene/single-site catalyst precursors are non-alkylated compounds, which requires an alkylation agent to do pre-activation alkylation if a boron based activator alone is used.1-2 Boron based activators with an aluminumalkyl compound (e.g., triisobutylaluminum) have been used for in-situ alkylation of non-alkylated metallocenes during activation, which usually requires largely excess aluminumalkyl compound for a complete activation.1, 3-4 Some boron based activators such as B(C6F5)3 are not stable with free aluminumalkyls due to serious Al-R/B-R exchanges. The present of excess free aluminumalkyls may also destroy the desired polymer properties. From our previous methylaluminoxane activation studies, we have concluded that, by using an aluminumalkyl as the alkylation agent, an activation system should provide three functions for the efficient activation of a non-alkylated metallocene: 1) cationization of the metallocene; 2) alkylation of the metallocene leaving groups (e.g., Cl); and (3) scavenging of the leaving groups.5 This contribution provide detailed studies on a boron-based activator system with aluminumalkyls as the alkylation agents and various choices of scavengers to support the three-function theory by using a so-called �post-activation alkylation� method to from stable, highly active boron based catalytic systems without excess aluminumalkyls in use. 1Bochmann, Organometallics, 2010 ; 2Chen and Marks, Chem. Rev., 2000 ; 3Baldwin, Bercaw, and Brintzinger, JACS, 2012 ; 4Marthis, Couzijn, and Chen, Organometallics, 2011; 5Luo and Diefenbach, Conference Abstract, Advances in Polyolefins (ACS), Santa Rosa, CA, 2011

Efficient activation of non-alkylated metallocenes with boron based activators

245th National Meeting (2013)

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