Synthesis and characterization of oxazoline-amine zirconium complexes for ethylene homo- and co-polymerization catalysis

Fang，Xian Ya1,2; Qin，Long2; Liu，Jiashuai2; Shi，Haonan2; Sun，Xiu Li2; Kuang，Xiaokang3; Gao，Yanshan2; Tang，Yong2

2023-04-15

10.1016/j.mcat.2023.113108

Molecular Catalysis   Impact Factor & Quartile

2468-8231

The development of group IV catalysts for homogeneous olefin polymerizations is crucial for both industrial and academic research. In this study, we present the synthesis and full characterization (H NMR, C NMR, Elem. Anal. and X-ray) of a new class of oxazoline-amine zirconium complexes. When used in combination with PhCB(CF) as the cocatalyst in the absence of scavenger, these complexes show high activity (up to 29.5 kg/(mol·min·atm)) in ethylene homopolymerization giving PE with M up to 392.4 kg/mol. On average, these complexes generate less than one polymer chain per catalyst, and negligible olefinic end groups were observed by NMR, both suggesting the absence or lack of chain transfer during polymerization. Furthermore, these complexes are also effective in ethylene/1-octene copolymerization, showing activity up to 42.9 kg/(mol·min·atm) and octene enchainment ratio up to 25.2 mol%. Gradually increasing the reaction time from 1 to 15 min leads to an increase in polymer M, chains/cat (up to 14.4) and a decrease in activity. Octene incorporation ratio increases from 12.6 to 17.9 mol% over reaction time (1 to 5 min) at 50 °C, likely suggesting mass transfer limitations at long reaction times. Increasing temperature from 50 °C to 90 °C leads to reduced activity and product M (> 5 ×), and increased chains/cat (≈5 ×) in the copolymerization. Olefinic end group analysis by H NMR suggests β-H elimination/transfer occurs after octene 2,1-insertion (vinylene; predominant), ethylene insertion (vinyl) and octene 1,2-insertion (vinylidene) at high temperatures.

Chain transfer Comonomer incorporation Ethylene polymerization Mass transfer Olefinic end group

English

Others

National Natural Science Foundation of China[U19B6001];

2-s2.0-85151284123

Scopus

1.College of Chemistry and Materials Science,Sichuan Normal University,Chengdu,5 Jing'an Road, Sichuan,610066,China
2.State Key Laboratory of Organometallic Chemistry,Shanghai Institute of Organic Chemistry,Chinese Academy of Sciences,Shanghai,345 Lingling Road,200032,China
3.Shenzhen Grubbs Institute and Department of Chemistry,Southern University of Science and Technology,Guangdong,China

Fang，Xian Ya,Qin，Long,Liu，Jiashuai,et al. Synthesis and characterization of oxazoline-amine zirconium complexes for ethylene homo- and co-polymerization catalysis[J]. Molecular Catalysis,2023,541.

Fang，Xian Ya.,Qin，Long.,Liu，Jiashuai.,Shi，Haonan.,Sun，Xiu Li.,...&Tang，Yong.(2023).Synthesis and characterization of oxazoline-amine zirconium complexes for ethylene homo- and co-polymerization catalysis.Molecular Catalysis,541.

Fang，Xian Ya,et al."Synthesis and characterization of oxazoline-amine zirconium complexes for ethylene homo- and co-polymerization catalysis".Molecular Catalysis 541(2023).