Stereoelective Polymerization of Racemic α-Olefins by Highly-Active Chirally Modified Ziegler-Natta Catalysts
The possibility of inducing the preferential polymerization of a single enantiomer from a racemic α-olefin(stereoelective polymerization) by using optically active Lewis bases firstly shown for conventional Ziegler-Natta catalysts(1), was extended by Pino and coworkers(2,3) to highlyactive systems such as MgCl2/TiCl4 ·B*/Al(i.Bu)3·B*. In this last case (-)-menthyl anisate(B*) was used both as “internal”(IB) and as “external” (EB) Lewis base. IB and EB can in general play different roles by interacting to different extent with the transition metal and the aluminum alkyl.
KeywordsEthyl Toluate MgCl Fractionation Diethyl
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