Synthetic Optimization and Scale-Up of Imino鈥揂mido Hafnium and Zirconium Olefin Polymerization Catalysts
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- 作者：Chunming Zhang ; Heqi Pan ; Jerzy Klosin ; Siyu Tu ; Arvind Jaganathan ; Philip P. Fontaine
- 刊名：Organic Process Research & Development
- 出版年：2015
- 出版时间：October 16, 2015
- 年：2015
- 卷：19
- 期：10
- 页码：1383-1391
- 全文大小：423K
- ISSN：1520-586X
文摘
Improved synthetic protocols were developed for the safe, efficient, and scalable preparation of imino鈥揳mido Hf and Zr complexes that are precatalysts for olefin polymerizations. Facile syntheses of four imino鈥揳mido complexes were achieved in high yields by direct reactions of 4 equiv of MeMgBr with mixtures of the corresponding bisimines or imine鈥揳mines and MCl4 (M = Hf, Zr). These synthetic routes eliminate the use of the pyrophoric reagents AlMe3 and n-BuLi used previously, avoid cryogenic conditions, and lead to significant yield improvements. Notably, competing reaction pathways between the bis-imine and MeLi were observed. This led to the discovery of the selective addition of MeMgBr to the bis-imine, which was successfully applied in the synthesis of the imine鈥揳mine ligand.