Oligomerization of ethylene using tridentate nickel catalysts bearing ether-pyrazol ligands with pendant O- and S-donor groups

Ulbrich, Ana H.D.P.S.; Bergamo, Adão L.; Casagrande, Osvaldo L.

doi:10.1016/j.catcom.2011.09.006

Cited by 25 publications

(16 citation statements)

References 75 publications

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“…For instance, an increase in ethylene pressure from 5 to 20 bar results in an increased activity from 500 to 1400 kg (mol Ni) −1 h −1 (Table , entries 2, 6 and 7). Consistent with literature reports, improved selectivity towards α‐olefins is also observed at higher pressure (Table , entries 2, 6 and 7) which may be attributed to chain transfer being favoured over chain isomerization …”

Section: Resultssupporting

confidence: 91%

Nickel(II) complexes bearing pyrazolylpyridines: synthesis, structures and ethylene oligomerization reactions

Nyamato

Alam

Ojwach

et al. 2015

Applied Organom Chemis

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Reactions of 2-bromo-6-(3,5-dimethyl-1H-pyrazol-1-yl)pyridine (L1) and 2,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)pyridine (L2) with NiCl 2 and NiBr 2 led to the formation of their respective metal complexes [NiCl 2 (L1)] (1), [NiBr 2 (L1)] (2) and [NiBr 2 (L2)] (3) in moderate to high yields. The complexes were characterized using elemental analyses, mass spectrometry and singlecrystal X-ray diffraction for 2. The solid-state structure of 2 confirmed the bidentate coordination mode of L1 and formation of a monometallic compound. Activation of the nickel(II) pre-catalysts with methylaluminoxane afforded active catalysts in the ethylene oligomerization reaction to produce mainly butenes (84-86%). In contrast, activation of nickel(II) pre-catalyst 2 with ethylaluminium dichloride resulted in partial Friedel-Crafts alkylation of the toluene solvent by the preformed oligomers. Complex structure, nature of co-catalyst employed, type of solvent and reaction conditions influenced the catalytic behaviour of these pre-catalysts.

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Section: Resultssupporting

confidence: 91%

Nickel(II) complexes bearing pyrazolylpyridines: synthesis, structures and ethylene oligomerization reactions

Nyamato

Alam

Ojwach

et al. 2015

Applied Organom Chemis

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“…In addition, the selectivity for a-C 4 also increased from 65% to 77%. Increased selectivity for a-C 4 with increase in ethylene concentration could be due to increased rate of dimerization, thus limiting parallel isomerization of 1-butene into 2-butenes [53]. We also observed that elevating the reaction temperature to 50 C from 30 C (Table 5, entry 15) resulted in reduction in catalytic activity which may result from thermal decomposition of the catalyst at high temperatures [50].…”

Section: Effect Of Reaction Conditions On Ethylene Oligomerization Rementioning

confidence: 72%

(Pyrazolyl)-(phosphinoyl)pyridine iron(II), cobalt(II) and nickel(II) complexes: Synthesis, characterization and ethylene oligomerization studies

Nyamato

Alam

Ojwach

et al. 2015

Journal of Organometallic Chemistry

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“…[17] More recently, Ojwach et al has also try to design unsymmetrical pyrazolyl-phosphine transition metal complexes containing a pyrazolyl unit and a secondary donor atom. [20,21] In this context, to gain a knowledge of the role of the pyrazolyl-phosphynoyl bidentate ligands in the catalytic performance of the nickel complexes, we decided to synthesize and characterize a new class of nickel (II) complexes of general formula [NiBr 2 (N, O) 2 ], and evaluate their catalytic performance for ethylene oligomerization. Thence, the authors reported the syntheses of a series of Fe (II), Co (II) and Ni (II) complexes with N,N,O pyrazolyl-phosphinoyl-pyridine ligands and evaluate their behavior in ethylene oligomerization reactions.…”

Section: Introductionmentioning

confidence: 99%

Pyrazolyl‐phosphinoyl nickel (II) complexes: synthesis, characterization and ethylene dimerization studies

Junges

Dresch

Costa

et al. 2019

Applied Organom Chemis

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A series of new nickel (II) complexes of general formula [NiBr 2 (N,O) 2 ] (Ni1-Ni5) based on bidentate pyrazolyl-phosphinoyl ligands were prepared and characterized by IR spectroscopy, elemental analysis, high-resolution mass spectrometry (HRMS), and X-ray crystallography for Ni1. X-ray crystallographic analyses of Ni1 revealed a six-coordinate species, in which Ni (II) lies in an octaedral environment. The nickel center is chelated by two pyrazolyl-phosphinoyl ligands with the two bromide ligands occupying mutually trans positions. Upon activation with methylaluminoxane (MAO), all nickel complexes were able to oligomerize ethylene with turnover frequencies (TOFs) varying from 5.0 to 16.6 × 10 3 (mol ethylene) (mol Ni) −1 h −1 producing selectively 1-butene (91.0-95.5 wt%). The substitution on the pyrazolyl group and the length of the backbone chain play a significant role in the catalytic activity. The use of MAO/TMA (1:1) or MAO/TiBA (1:1) instead of MAO drastically reduced the activities. The TMA content has no significant influence on the selectivity. However, the use of TiBA leads to a reduction of 1-butene (from 94.9 to 71.0 wt%) and an improvement in the hexene production (from 1.5 to 23.3 wt%). Under optimized reaction conditions (10°C, 20 min, 20 bar ethylene, [Al/Ni] = 600), Ni1/MAO catalytic system yielded TOF = 24.7 × 10 3 (mol ethylene) (mol Ni) −1 h −1 with good selectivities for α-C4 (94.9 wt%).

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Oligomerization of ethylene using tridentate nickel catalysts bearing ether-pyrazol ligands with pendant O- and S-donor groups

Cited by 25 publications

References 75 publications

Nickel(II) complexes bearing pyrazolylpyridines: synthesis, structures and ethylene oligomerization reactions

Nickel(II) complexes bearing pyrazolylpyridines: synthesis, structures and ethylene oligomerization reactions

(Pyrazolyl)-(phosphinoyl)pyridine iron(II), cobalt(II) and nickel(II) complexes: Synthesis, characterization and ethylene oligomerization studies

Pyrazolyl‐phosphinoyl nickel (II) complexes: synthesis, characterization and ethylene dimerization studies

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