Xiong Shuoyan, Hong Alexandria, Ghana Priyabrata, Bailey Brad C, Spinney Heather A, Bailey Hannah, Henderson Briana S, Marshall Steve, Agapie Theodor
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
Chemical Science, Core R&D, The Dow Chemical Company, Midland, Michigan 48667, United States.
J Am Chem Soc. 2023 Dec 6;145(48):26463-26471. doi: 10.1021/jacs.3c10800. Epub 2023 Nov 22.
Polar monomer-induced β-H elimination is a key elementary step in polar polyolefin synthesis by coordination polymerization but remains underexplored. Herein, we show that a bulky neutral Ni catalyst, , is not only a high-performance catalyst in ethylene/acrylate copolymerization (activity up to ∼37,000 kg/(mol·h) at 130 °C in a batch reactor, mol % tBA ∼ 0.3) but also a suitable platform for investigation of acrylate-induced β-H elimination. , a novel Ni alkyl complex generated after acrylate-induced β-H elimination and subsequent acrylate insertion, was identified and characterized by crystallography. A combination of catalysis and mechanistic studies reveals effects of the acrylate monomer, bidentate ligand, and the labile ligand (e.g., pyridine) on the kinetics of β-H elimination, the role of β-H elimination in copolymerization catalysis as a chain-termination pathway, and its potential in controlling the polymer microstructure in polar polyolefin synthesis.
极性单体诱导的β-H消除是配位聚合合成极性聚烯烃过程中的一个关键基元步骤，但仍未得到充分研究。在此，我们表明一种大位阻中性镍催化剂不仅是乙烯/丙烯酸酯共聚反应中的高性能催化剂（在间歇反应器中130℃下活性高达约37,000 kg/(mol·h)，叔丁醇丙烯酸酯摩尔百分比约为0.3），而且是研究丙烯酸酯诱导的β-H消除的合适平台。通过晶体学鉴定并表征了丙烯酸酯诱导的β-H消除及随后的丙烯酸酯插入后生成的新型镍烷基配合物。催化研究和机理研究相结合揭示了丙烯酸酯单体、双齿配体和不稳定配体（如吡啶）对β-H消除动力学的影响、β-H消除在共聚催化中作为链终止途径的作用及其在控制极性聚烯烃合成中聚合物微观结构方面的潜力。
