Stereospecific Living Ziegler-Natta Polymerization via Rapid and Reversible Chloride Degenerative Transfer between Active and Dormant Sites

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• 作者：Yonghui Zhang and Lawrence R. Sita
• 刊名：Journal of the American Chemical Society
• 出版年：2004
• 出版时间：June 30, 2004
• 年：2004
• 卷：126
• 期：25
• 页码：7776 - 7777
• 全文大小：48K
• 年卷期：v.126,no.25(June 30, 2004)
• ISSN：1520-5126

文摘

The successful realization of a stereospecific chloride degenerative transfer living Ziegler-Natta polymerization process that provides isotactic polyolefins of narrow polydispersity (M_w/M_n mages/entities/le.gif"> 1.05) is documented. Variable-temperature NMR studies confirm the configurational stability of all species with respect to metal-centered epimerization and large magnitudes for both k_{mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">} and k_{-mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">}. Additional kinetic analyses with an increasing concentration of the dormant state establish that k_{mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">} is larger than k_{-mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">}. Finally, [Et₃Si][B(C₆F₅)₄] has been shown to be an effective substoichiometric halide abstractor for chloride degenerative transfer Ziegler-Natta polymerization.