Nitrogen-Linked Diphosphine Ligands with Ethers Attached to Nitrogen for Chromium-Catalyzed Ethylene Tri- and Tetramerizations

Elowe, Paul R.; Mccann, Cassandra; Pringle, Paul G.; Spitzmesser, Stefan K.; Bercaw, John E.

doi:10.1021/om0601596

Cited by 122 publications

(82 citation statements)

References 20 publications

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“…Our results are generally in agreement with these studies. 51,71 It is noteworthy that in previous reports the longer chain oligomeric products are reported to be either C 11+ linear alpha olefins 71 or C 10 isomers (through the cotrimerisation of 1-hexene and ethylene) and C 12 isomers (through the co-trimerisation of 1-octene and ethylene), 51 however the co-trimeric isomers were not present in our catalytic mixtures. Detailed analysis of the liquid phase for ligands 10-12 in conjunction with MAO reveals some interesting features.…”

Section: Methodsmentioning

confidence: 50%

A survey of pendant donor-functionalised (N,O) phosphine ligands for Cr-catalysed ethylene tri- and tetramerisation

Suttil

Wasserscheid

McGuinness

et al. 2014

Catal. Sci. Technol.

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In this study three classes of ligands are explored for ethylene tri-/tetramerisation in conjunction with chromium and both triethylaluminium (AlEt 3 ) and methylaluminoxane (MAO) co-catalysts. Hydrazine based ligands containing an N-H functionality [PN(NH)P], analogous to Rosenthal's previously reported PNPNH system, show selectivity towards 1-hexene and 1-octene formation in conjunction with AlEt 3 , and act as PNP tetramerisation analogues when MAO is employed. PNP ligands containing non-protic pendant donor moieties generally show poor activity and selectivity when AlEt 3 is employed as an activator, however when MAO is used good activities and selectivities are achieved. n-Propylcyclopentane and 2-propenylcyclopentane, and higher homologues, are produced during catalysis when oxygen is the donor atom. The formation of such products is discussed with respect to the generation of methylenecyclopentane and methylcyclopentane by PNP based tetramerisation catalysts. Simple phosphine ligands containing O-H functionalisation are also explored and it was shown that the catalyst selectivity is highly dependent on both the activator and structural features of the ligand employed.

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Section: Methodsmentioning

confidence: 50%

A survey of pendant donor-functionalised (N,O) phosphine ligands for Cr-catalysed ethylene tri- and tetramerisation

Suttil

Wasserscheid

McGuinness

et al. 2014

Catal. Sci. Technol.

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“…Upon activation with MAO (methylaluminoxane), these catalytic systems can trimerize ethylene to 1-hexene with unprecedented selectivity and productivity. NZN ligands (multidentate nitrogen-, oxygen-, or sulfur-bridged bis(imino) ligands [14,15], with some exceptions [16]), PNP ligands (chelating nitrogen-bridged diphosphine ligands) [17,18] and SNS ligands (chelating nitrogen-bridged disulfur ligands) [17,19] are the three different kinds of mixed-donor ligands investigated most for ethylene oligomerization.…”

Section: Synthesis and Properties Of Chromium-based Catalysts With DImentioning

confidence: 99%

“…Bollmann et al reported a kind of nitrogen-linked diphosphine PNP ligands for ethylene trimerization and tetramerization [7,17,18]. Although the common belief was that ethylene tetramerization is improbable, they, for the first time, reported an ethylene tetramerization reaction that produced 1-octene in good selectivity.…”

Section: Pnp Ligandsmentioning

confidence: 99%

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Recent Research Progress in Preparation of Ethylene Oligomers with Chromium-Based Catalytic Systems

Zhu

Wang

2011

Designed Monomers and Polymers

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Ethylene oligomers, notably 1-hexene and 1-octene, are usually used as co-monomers in the production of linear low-density polyethylene (LLDPE). Because of the great value of 1-hexene and 1-octene, there have been many reports on the selective oligomerization of ethylene to 1-hexene and 1-octene recently. Research of ethylene oligomerization focuses mainly on the synthesis of catalysts and the mechanism of oligomerization. Much of this research concerns investigation into a catalytic system that can oligomerize ethylene to 1-hexene or 1-octene with high selectivity and activity. Different kinds of catalysts have been synthesized to catalyze the reactions, and the chromium-based homogeneous catalysts are found to be the most suitable ones. This article reviews the recent research progress in synthesis of chromium catalyst systems and study on the mechanism of ethylene oligomerization catalyzed by these catalysts.

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“…Since the first report of ethylene tetramerization to form 1-octene using Cr-bis(diphenylphosphino)amine (PNP) catalysts [9], numerous studies have investigated the relationship between ligand structure and catalytic properties. These include investigations into various single-site PNP ligands, wherein alkyl [10][11][12], cycloalkyl [13], ether [14], thioether, pyridyl tethers [15] and aryl [16,17] substituents attached to the N or P atom of the ligand backbone were synthesized and evaluated. Several dual-site PNP ligands [12,18] and a triple-site [19] were also found to have moderate activity and selectivity toward 1-octene in ethylene tetramerization.…”

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confidence: 99%

Ethylene tetramerization with a highly active and long-lifetime trinuclear diphenylphosphinoamine/Cr(III)/MAO catalyst

et al. 2012

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The synthesis and characterization of a novel trinuclear diphosphinoamine ligand 2 are reported. The ligand combined with Cr(III), activated with methylaluminoxane, lead to highly active and long-lifetime catalytic systems for the tetramerization of ethylene to form 1-octene. The effects of reaction temperature, reaction pressure, molar ratio of Al/Cr and bis(diphenylphosphino)amine/Cr on the catalytic activity and product selectivity were studied. Compared with its mononuclear analogue 1, ligand 2 showed a higher catalytic activity and longer lifetime for ethylene tetramerization in the presence of methylaluminoxane as cocatalyst. High molecular weight polyethylene was generated as a by-product with extremely broad molecular weight distributions. In recent years there has been a substantial acceleration in research activity concerned with homogeneous transition metal catalysts for ethylene oligomerization and polymerization. Chromium catalysts play an important role in both of these processes [1][2][3][4][5][6][7][8]. Since the first report of ethylene tetramerization to form 1-octene using Cr-bis(diphenylphosphino)amine (PNP) catalysts [9], numerous studies have investigated the relationship between ligand structure and catalytic properties. We were attracted by the potential for using chromium as an ethylene tetramerization active center because of its high catalytic activity and high selectivity to 1-octene. Here, we describe a new trinuclear PNP ligand that displays higher activity and a long lifetime for ethylene tetramerization to 1-octene.

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Nitrogen-Linked Diphosphine Ligands with Ethers Attached to Nitrogen for Chromium-Catalyzed Ethylene Tri- and Tetramerizations

Cited by 122 publications

References 20 publications

A survey of pendant donor-functionalised (N,O) phosphine ligands for Cr-catalysed ethylene tri- and tetramerisation

A survey of pendant donor-functionalised (N,O) phosphine ligands for Cr-catalysed ethylene tri- and tetramerisation

Recent Research Progress in Preparation of Ethylene Oligomers with Chromium-Based Catalytic Systems

Ethylene tetramerization with a highly active and long-lifetime trinuclear diphenylphosphinoamine/Cr(III)/MAO catalyst

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