(Ferrocenylpyrazolyl)nickel(<scp>ii</scp>)-catalysed ethylene oligomerisation

Obuah, Collins; Jordaan, Johannes H.; Darkwa, James

doi:10.1039/c5cy02055g

“…Production of linear α-olefins (LAOs) through ethylene oligomerization is an important issue in both industry and academia, − and development of efficient catalysts for this process is an active research area. − LAOs are used in the polyolefin industry as comonomers, and demand for them has increased with the increase in polyolefin production using the homogeneous metallocene-type catalysts. Recently, LAOs have also been used in the production of poly(α-olefin) lubricant base-stocks .…”

Section: Introductionmentioning

confidence: 99%

Methylaluminoxane-Free Chromium Catalytic System for Ethylene Tetramerization

Kim

¹

,

Lee

²

,

Jeong

³

et al. 2017

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Ethylene tetramerization catalyst systems comprising a Cr(III) complex containing PNP ligands and methylaluminoxane (MAO) are useful for the production of 1-octene. However, a concern with these systems is the use of expensive MAO in excess. Herein, we report a catalytic system that avoids the use of MAO. Metathesis of CrCl 3 (THF) 3 and [(CH 3 CN) 4 Ag] + [B(C 6 F 5 ) 4 ] − afforded [L 4 Cr III Cl 2 ] + [B(C 6 F 5 ) 4 ] − (L = CH 3 CN or tetrahydrofuran (THF)), which was converted to [(PNP)CrCl 2 L 2 ] + [B(C 6 F 5 ) 4 ] − , where PNP is iPrN(PPh 2 ) 2 ( 1 ) or [CH 3 (CH 2 ) 16 ] 2 CHN(PPh 2 ) 2 ( 2 ). The molecular structures of [(THF) 4 Cr III Cl 2 ] + [B(C 6 F 5 ) 4 ] − and [ 1 -CrCl 2 (THF) 2 ] + [B(C 6 F 5 ) 4 ] − were unambiguously determined by X-ray crystallography. The cationic (PNP)Cr III complexes paired with [B(C 6 F 5 ) 4 ] − anions, that is, [(PNP)CrCl 2 (CH 3 CN) 2 ] + [B(C 6 F 5 ) 4 ] − , exhibited high activity in chlorobenzene when activated with common trialkylaluminum species (Me 3 Al, Et 3 Al, and iBu 3 Al). The activities and selectivity were comparable to those of the original MAO-based Sasol system ( 1 -CrCl 3 /MAO). When activated with Et 3 Al or iBu 3 Al, the Cr complex, [ 2 -CrCl 2 (CH 3 CN) 2 ] + [B(C 6 F 5 ) ...

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“…However, this mechanism much worse describes the distribution of products formed during the oligomerization of 1-hexene, because it requires the preferable β-C 2 H 5 elimination. The possible formation of odd carbon number olefins, as a result of side-reactions in the presence of the EtAlCl 2 , is not supported neither by literature [57,[66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82] nor by experimental data (SI, Figure S51).…”

Section: Formation Of Odd Carbon Number Olefinsmentioning

confidence: 91%

NNNO‐Heteroscorpionate nickel (II) and cobalt (II) complexes for ethylene oligomerization: the unprecedented formation of odd carbon number olefins

Zubkevich

¹

,

Тuskaev

²

,

Гагиева

³

et al. 2020

Applied Organom Chemis

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The unprecedented observation of odd carbon number olefins is reported during nickel‐ catalyzed ethylene oligomerization. Two complexes based on Co (II) and Ni (II) with novel tetradentate heteroscorpionate ligand have been synthesized and fully characterized. These complexes showed the ability to oligomerize ethylene upon activation with various organoaluminum compounds (Et2AlCl, Et3Al2Cl3, EtAlCl2, MMAO). Ni (II) based catalytic systems were sufficiently more active (up to 1900 kg·mol (Ni)−1·h−1·atm−1) than Co (II) analogs and have been found to be strongly dependent on the activator composition. The use of PPh3 as an additive to catalytic systems resulted in the increase of activity up to 4,150 kg·mol (Ni)−1·h−1·atm−1 and in the alteration of selectivity. All Ni (II) based systems activated with EtAlCl2 produce up to 5 mol. % of odd carbon number olefins; two probable mechanisms for their formation are suggested – metathesis and β‐alkyl elimination.

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“…74 In the presence of MAO, the ferrocenyl phosphane nickel(0) complex 30 described by Lang et al 111 displays low activity and forms hexenes as the main product followed by butenes and higher oligomers (Table 5). Darkwa et al 112 suggest that the use of bulky ferrocenyl groups in pyrazolyl ligands may enhance catalyst stability and thus favor the activity of the catalytic system. Complexes 31−33 (Figure 18) are active in the presence of AlEtCl 2 and form butenes and higher oligomers from C 16 + without C 6 −C 14 oligomers.…”

Section: Neutral Ligandsmentioning

confidence: 99%

Nickel Catalyzed Olefin Oligomerization and Dimerization

Olivier‐Bourbigou

¹

,

Breuil

²

,

Magna

³

et al. 2020

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Brought to life more than half a century ago and successfully applied for high-value petrochemical intermediates production, nickel-catalyzed olefin oligomerization is still a very dynamic topic, with many fundamental questions to address and industrial challenges to overcome. The unique and versatile reactivity of nickel enables the oligomerization of ethylene, propylene and butenes into a wide range of oligomers that are highly sought-after in numerous fields to be controlled. Interestingly, both homogeneous and heterogeneous nickel catalysts have been scrutinized and employed to do this. This rare specificity encouraged us to interlink them in this review so as to open up opportunities for further catalyst development and innovation. An in-depth understanding of the reaction mechanisms in play is essential to being able to fine-tune the selectivity and achieve efficiency in the rational design of novel catalytic systems. This review thus provides a complete overview of the subject, compiling the main fundamental/industrial milestones and remaining challenges facing homogeneous/heterogeneous approaches as well as emerging catalytic concepts, with a focus on the last 10 years.

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(Ferrocenylpyrazolyl)nickel(ii)-catalysed ethylene oligomerisation

Abstract: (Ferrocenylpyrazolyl)nickel(ii) complexes upon activation with EtAlCl2 catalyse ethylene oligomerisation reactions in chlorobenzene to isomers of butenes and C16–C64 olefins without Schulz–Flory distribution.

Cited by 16 publications

References 71 publications

Methylaluminoxane-Free Chromium Catalytic System for Ethylene Tetramerization

Methylaluminoxane-Free Chromium Catalytic System for Ethylene Tetramerization

NNNO‐Heteroscorpionate nickel (II) and cobalt (II) complexes for ethylene oligomerization: the unprecedented formation of odd carbon number olefins

Nickel Catalyzed Olefin Oligomerization and Dimerization

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