Highly efficient asymmetric (diphenylphosphino)benzene‐based chromium catalysts for selective ethylene trimerization

Ma, Jing; Fan, Haonan; Hao, Biao‐Biao; Jiang, Tao

doi:10.1002/aoc.6907

Cited by 9 publications

(6 citation statements)

References 23 publications

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“…Diphosphine ligands L 1 and L 2 were prepared according to literature methods, respectively. , Mixed PR 2 /PPh 2 (R = Et) diphosphine ligand L 3 and PPhR/PPh 2 (R = Cy, i Pr, Et) diphosphine ligands ( L 4 – L 7 ) were prepared by a two-step synthesis according to literature methods (Scheme ). , The corresponding Cr complexes 1 – 7 were prepared by reaction of the ligands ( L 1 – L 7 ) with CrCl 3 (THF) 3 , respectively (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

“…Ligand L 8 was obtained from commercial sources. 2-Bromophenyldiphenylphosphine, (2-bromo-4-methoxyphenyl)diphenylphosphine, chlorodiethylphosphane, chloro(cyclohexyl)(phenyl)phosphane, chloro(isopropyl)(phenyl)phosphane, chloro(ethyl)(phenyl)phosphane, ligand L 1 , ligand L 2 , and complex 8 were prepared by literature methods. The 1 H NMR spectra and 31 P NMR spectra of ligand L 1 – L 2 are shown in Figures S1–S4.…”

Section: Methodsmentioning

confidence: 99%

“…Inspired by our successful use of the PCCP ligands in ethylene tri-/tetramerization, , especially C , we envisioned that phenylene-bridged mixed alkyl/aryl diphosphine ligands G and H might have advantages over their PPh 2 and P(alkyl) 2 counterparts, i.e., D and E , such as high activity, controllable selectivity, and low PE selectivity. During the course of this work, we became aware of the very recent publication by the Jiang group, describing the use of similar ligands G and H bearing a P-ethyl or P-isopropyl group in ethylene oligomerization . However, these catalysts exhibited ethylene trimerization rather than tetramerization, producing a very low 1-octene selectivity of <6 wt % and considerable PE formation (0.2–1.7 wt %).…”

Section: Introductionmentioning

confidence: 99%

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Ethylene Tri-/Tetramerization Catalysts Supported by Phenylene-Bridged Mixed Alkyl/Aryl Diphosphine Ligands

Kong

Zuo

et al. 2023

Organometallics

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Cr(III) complexes supported by phenylene-bridged diphosphine ligands with P-alkyl substitution were prepared and evaluated in ethylene tri-/tetramerization. The ligand steric and electronic properties have significantly influenced the catalytic activity. The Cr complex 1 based on a bulky PCy2 phosphine ligand L 1 having a stronger σ-donor ability exhibited the highest activity, which is more reactive than its PPh2 counterpart 8. The selectivity toward ethylene tri-/tetramerization is mainly determined by the steric property of ligands. Reducing the ligand steric bulk switched the selectivity from predominant trimerization into mixed tri-/tetramerization. 1 achieved a high 1-hexene selectivity of 82.5 wt % with a 1-octene selectivity of 9.7 wt %, while 4 based on L4 bearing a less bulky PPhCy group gave a considerable 1-octene selectivity of 43.3 wt % with a very high activity of 1874 kg·gCr –1·h–1. 1 also exhibited a high activity even at a relatively low temperature of 40 °C, while both 4 and 5 based on a PPh(alkyl) diphosphine ligand gave poor activities at 40 °C. More importantly, these Cr complexes showed a very low PE selectivity of ≤0.1 wt %.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ethylene Tri-/Tetramerization Catalysts Supported by Phenylene-Bridged Mixed Alkyl/Aryl Diphosphine Ligands

Kong

Zuo

et al. 2023

Organometallics

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“…Catalyst development for selective olefin oligomerization remains a hot research topic in both academia and industry. [35][36][37][38][39][40][41][42][43][44][45] Cr complexes with privileged ligands are instrumental in numerous catalytic processes. 46,47…”

Section: Introductionmentioning

confidence: 99%

“…In this study, we present the outcomes of our research efforts, focusing on the synthesis of Cr precursors and the target Cr catalyst. Catalyst development for selective olefin oligomerization remains a hot research topic in both academia and industry 35–45 . Cr complexes with privileged ligands are instrumental in numerous catalytic processes 46,47 …”

Section: Introductionmentioning

confidence: 99%

Preparation of chromium complexes for ethylene tetramerization catalyst

Park,

Baek

et al. 2024

Bulletin Korean Chem Soc

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One of the remaining challenges in the commercialization of a highly efficient ethylene tetramerization catalyst, [1‐CrCl2][B(C6F5)4] (1=iPrN[P(C6H4Si(Octyl)3)2]2), is the generation of small amounts of polyethylene (PE). To address this issue, we explored different activator options and found that (Octyl)3Al was the most effective choice. Building on the observation that [iPrN(PPh2)2]CrCl3(THF) was not completely alkylated by the action of excess Me3Al to form ([iPrN(PPh2)2]Cr(μ2‐Cl)(ClMe2AlClAlMe3))2, we synthesized [ortho‐(MeO)C6H4CH2‐η1C:κO]3Cr, developing a catalytic system comprising this precursor, PNP ligand 1, and [MeN(H)(C18H37)2][B(C6F5)4]. However, this catalytic system exhibited a long induction time (~30 min) and generated a significant amount of PE. Returning to the catalytic system of [1‐CrCl2][B(C6F5)4], we successfully achieved the conversion of [(EtOH)4CrCl2][B(C6F5)4] to [(CH3CN)4CrCl2][B(C6F5)4] at a large scale by designing a specialized glass apparatus. Finally, we discovered that the generation of PE could be reduced by adjusting the reaction conditions during the synthesis of [1‐CrCl2][B(C6F5)4].

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High Activity Ethylene Oligomerization Using Asymmetric Alkyl P‐Substituted Bis(phosphanyl)amine Ni(II) complexes

Shao,

Zhang,

Yang

et al. 2024

Applied Organom Chemis

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A series of novel asymmetric alkyl P‐substituted bis(phosphanyl)amine (PNP) Ph2PN (cyclopentyl) PR1R2‐type L1–L5 ligands and these corresponding Ni(II) precatalysts C1–C5 were synthesized and characterized. The structures of these complexes were confirmed by using 1H‐, 31P‐, 13C‐NMR, FT‐IR, and elemental analysis. Using ethylaluminum dichloride (EADC) as a cocatalyst, nickel complexes exhibited high activity in elective ethylene oligomerization, with the main products being dimers and a small number of trimers. Under optimized conditions of 60°C and 1.0 MPa ethylene pressure, C4, bearing a diisopropylphosphoryl group, exhibited highest catalytic activity of 1342.9 kg·g Ni−1·h−1 with 85.2% C4 and 14.8% C6 products selectivity, while C2, bearing a diethylphosphonyl group, showed catalytic activity of 596.4 kg·g Ni−1·h−1 with 88.2% C4 and 11.8% C6 product selectivity. Single crystal analysis offered a more comprehensive insight into the subtle effects of alkyl P‐substituted in the scaffold of C2 and C4 ligands on catalytic activity. Density functional theory (DFT) calculations indicated that lower energy of the LUMO in the C4A intermediate enhances the activity of ethylene oligomerization. It provides a new method for purposefully designing ligands for ethylene oligomerization with high catalytic activity.

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Highly efficient asymmetric (diphenylphosphino)benzene‐based chromium catalysts for selective ethylene trimerization

Cited by 9 publications

References 23 publications

Ethylene Tri-/Tetramerization Catalysts Supported by Phenylene-Bridged Mixed Alkyl/Aryl Diphosphine Ligands

Ethylene Tri-/Tetramerization Catalysts Supported by Phenylene-Bridged Mixed Alkyl/Aryl Diphosphine Ligands

Preparation of chromium complexes for ethylene tetramerization catalyst

High Activity Ethylene Oligomerization Using Asymmetric Alkyl P‐Substituted Bis(phosphanyl)amine Ni(II) complexes

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