Mechanisms for the effects of fluorine and α-diimine backbone structure on the catalyst behavior and catalyst deactivation in ethylene polymerization by Ni catalysts

Ahmadjo, Saeid; Damavandi, Saman; Zohuri, Gholamhossein; Farhadipour, Abolghasem; Etemadinia, Z.

doi:10.1016/j.jorganchem.2017.02.043

Cited by 18 publications

(17 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This finding suggested that the ortho-F substitution suppressed chain-walking and favored β-H elimination. The explanation for this observation is uncertain but may be due to weak hydrogen bonding between the ortho-fluorine atoms and the coordinated ethylene during the insertion transition state; similar results have been observed elsewhere [39][40][41]. This lower branching content of the polyethylene formed by Ni4 was also consistent with the higher Tm of the polymer.…”

Section: Microstructural Analysis Of the Polyethylenessupporting

confidence: 77%

Remote dibenzocycloheptyl-substitution of an iminotrihydroquinoline-nickel catalyst as a route to narrowly dispersed branched polyethylene waxes with alkene functionality

Guo

Zhu

Zhang

et al. 2018

European Polymer Journal

View full text Add to dashboard Cite

The 8-(arylimino)-5,6,7-trihydroquinoline-nickel(II) chlorides, [8-N{2,6-R2-4-(C15H13)C6H2}C9H8N]NiCl2 (R = Me Ni1, Et Ni2, i-Pr Ni3, F Ni4, Cl Ni5), each appended with a remote para-dibenzocycloheptyl group, have been synthesized from either the pre-formed ligand (Ni1-Ni3) or by generating the ligand in-situ during complexation (Ni4, Ni5). The molecular structures of Ni2 and Ni3 adopt dimeric or trimeric forms in the solid state, in which the chlorides can act as doubly or triply bridging ligands. On treatment with either MMAO or Et2AlCl, Ni1-Ni5 showed low (Ni4, Ni5) to high activities (Ni1-Ni3: up to 4.58 × 10 6 g PE mol-1 (Ni) h-1) for ethylene polymerization producing unsaturated polyethylenes of low molecular weight (1.4-2.7 kg•mol-1) and narrow dispersity (< 2.0). In the main, these polyethylene waxes are highly branched and contain relatively high levels of internal vinylenes (-CH=CH-) with respect to terminal vinyls (-CH=CH2). The ortho-substituents of the precatalyst were found to not only affect the catalytic activity but also the vinylene:vinyl ratio and the branching content. Notably, the materials generated using ortho-fluoro Ni4/Et2AlCl possessed the least number of branches and an increased vinyl contribution. Furthermore, these unsaturated polyethylenes can be readily functionalized by epoxidation with almost quantitative conversion.

show abstract

Section: Microstructural Analysis Of the Polyethylenessupporting

confidence: 77%

Remote dibenzocycloheptyl-substitution of an iminotrihydroquinoline-nickel catalyst as a route to narrowly dispersed branched polyethylene waxes with alkene functionality

Guo

Zhu

Zhang

et al. 2018

European Polymer Journal

View full text Add to dashboard Cite

show abstract

“…10) possessing various backbone structures. 89,90 The acenaphthoquinone-based catalyst in ethylene polymerization exhibited a moderate activity of 1.4 × 10 4 g PE (mol Ni h) −1 (30°C, 30 min). 89 Despite the steric openness of these ligands, molecular weights of up to 2.48 × 10 5 g mol −1 with good crystallinity (58%) were generated.…”

Section: Fig 17mentioning

confidence: 99%

“…89,90 The acenaphthoquinone-based catalyst in ethylene polymerization exhibited a moderate activity of 1.4 × 10 4 g PE (mol Ni h) −1 (30°C, 30 min). 89 Despite the steric openness of these ligands, molecular weights of up to 2.48 × 10 5 g mol −1 with good crystallinity (58%) were generated. The introduction of ortho-fluorine into the ligand's N-aryl can effectively retard the β-hydride elimination through the influence of F-H bonds, leading to semicrystalline polymers.…”

Section: Fig 17mentioning

confidence: 99%

See 1 more Smart Citation

A continuing legend: the Brookhart-type α-diimine nickel and palladium catalysts

2019

View full text Add to dashboard Cite

show abstract

“…Initial reports by Brookhart and co‐workers revealed that complexes of nickel and palladium bearing sterically hindered α‐diimine ligands could generate high‐molecular‐weight polymers with high catalytic activity in ethylene polymerization . The properties and reactions of metal complexes are highly dependent on the selection of supporting ligand(s), and this selection is one of the keys to successful coordination chemistry. Late transition metal catalysts based on bulky bis)imine(ligands usually depend on the structures of ligands and ortho ‐position groups on the aryl rings that showed very interesting behaviours in olefin polymerization .…”

Section: Introductionmentioning

confidence: 99%

Single and binary catalyst systems based on nickel and palladium in polymerization of ethylene

Kimiaghalam

Nasr‐Isfahani

Zohuri

et al. 2017

Applied Organom Chemis

View full text Add to dashboard Cite

The catalyst (N,N‐bis(2,6‐dibenzhydryl‐4‐ethoxyphenyl)butane‐2,3‐diimine)nickel dibromide, a late transition metal catalyst, was prepared and used in ethylene polymerization. The effects of reaction parameters such as polymerization temperature, co‐catalyst to catalyst molar ratio and monomer pressure on the polymerization were investigated. The α‐diimine nickel‐based catalyst was demonstrated to be thermally robust at a temperature as high as 90 °C. The highest activity of the catalyst (494 kg polyethylene (mol cat)−1 h−1) was obtained at [Al]/[Ni] = 600:1, temperature of 90 °C and pressure of 5 bar. In addition, the performance of a binary catalyst using nickel‐ and palladium‐based complexes was compared with that of the corresponding individual catalytic systems in ethylene polymerization. In a study of the catalyst systems, the average molecular weight and molecular weight distribution for the binary polymerization were between those for the individual catalytic polymerizations; however, the binary catalyst activity was lower than that of the two individual ones. The obtained polyethylenes had high molecular weights in the region of 105 g mol−1. Gel permeation chromatography analysis showed a narrow molecular weight distribution of 1.44 for the nickel‐based catalyst and 1.61 for the binary catalyst system. The branching density of the polyethylenes generated using the binary catalytic system (30 branches/1000 C) was lower than that generated using the nickel‐based catalyst (51/1000 C). X‐ray diffraction study of the polymer chains showed higher crystallinity with lower branching of the polymer obtained. Also Fourier transform infrared spectra confirmed that all obtained polymers were low‐density polyethylene.

show abstract

Mechanisms for the effects of fluorine and α-diimine backbone structure on the catalyst behavior and catalyst deactivation in ethylene polymerization by Ni catalysts

Cited by 18 publications

References 25 publications

Remote dibenzocycloheptyl-substitution of an iminotrihydroquinoline-nickel catalyst as a route to narrowly dispersed branched polyethylene waxes with alkene functionality

Remote dibenzocycloheptyl-substitution of an iminotrihydroquinoline-nickel catalyst as a route to narrowly dispersed branched polyethylene waxes with alkene functionality

A continuing legend: the Brookhart-type α-diimine nickel and palladium catalysts

Single and binary catalyst systems based on nickel and palladium in polymerization of ethylene

Contact Info

Product

Resources

About