Activation of Single-Component Nickel(II) Polyethylene Catalysts via Phase Transfer of Fluorous Phosphine Ligands

Xi, Zhenxing; Bazzi, Hassan S.; Gladysz, J. A.

doi:10.1021/jacs.5b06562

Cited by 23 publications

(28 citation statements)

References 30 publications

(21 reference statements)

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“…[50] Polymerizations are carried out under ac onstant pressure of 8atm using monophasic (toluene) and biphasic (toluene/ PFMC)c onditions. [51] As showni nF igure 8, appreciable phase-transfer activation occurred,w ith that for 27 a greatert han that for 27 b.T he phosphine ligand in the latter is, owing to the additional methylene groups,l ess fluorophilic.…”

Section: Other Catalysts or Reactionsmentioning

confidence: 91%

Phase‐Transfer Activation of Transition Metal Catalysts

Tuba

Bazzi

et al. 2015

Chemistry A European J

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With metal-based catalysts, it is quite common that a ligand (L) must first dissociate from a catalyst precursor (L'n M-L) to activate the catalyst. The resulting coordinatively unsaturated active species (L'n M) can either back react with the ligand in a k-1 step, or combine with the substrate in a k2 step. When dissociation is not rate determining and k-1 [L] is greater than or comparable to k2 [substrate], this slows the rate of reaction. By introducing a phase label onto the ligand L and providing a suitable orthogonal liquid or solid phase, dramatic rate accelerations can be achieved. This phenomenon is termed "phase-transfer activation". In this Concept, some historical antecedents are reviewed, followed by successful applications involving fluorous/organic and aqueous/organic liquid/liquid biphasic catalysis, and liquid/solid biphasic catalysis. Variants that include a chemical trap for the phase-labeled ligands are also described.

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Section: Other Catalysts or Reactionsmentioning

confidence: 91%

Phase‐Transfer Activation of Transition Metal Catalysts

Tuba

Bazzi

et al. 2015

Chemistry A European J

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“…[19] These diverse applicationsc onvincingly validate the concept positedi n Scheme 1a nd show that it can be reliably exploited. In recent studies, the applicabilityo ft his protocolt on ickel-catalyzed ethylene polymerization was also demonstrated.…”

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confidence: 54%

“…[14] The perfluoroalkyl segmentsi n5 render it less basic than pyridine. Thus,t od rive the reaction, as eries of freeze/ pump/thaw cycles were conducted with fresh charges of CF 3 C 6 H 5 .A lthough most of the pyridine volatilized, trace amountso f5 remained, affording a9 3% yield of 7 of approximately 95 %p urity,a sa ssayed by the signal for Ru = CHPh in the 1 HNMR spectrum.N onetheless, the CF 3 C 6 F 11 /toluenep artition coefficient (39.8:60.2) could be determined by 19 FNMR spectroscopy,a sd escribed in the Supporting Information. This shows the complex to be predominantly lipophilic, suited for phase-transfer activation as in Schemes 1a nd 3.…”

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confidence: 99%

“…Rates of formation of 8b (roomtemperature, [8a] 0 = 0.010 m, 1mol % 7). [1,19] In exploratory efforts, attempts werem ade to preparea nalogues of 7 with as ingle (CH 2 ) 2 R f8 group on each pyridine ligand. Solvent/catalyst systems: & CD 2 Cl 2 (0.7 mL, monophasic), 1mol % 7; * CD 2 Cl 2 (0.7 mL, monophasic), 1mol % 3;~CD 2 Cl 2 /perfluoro(methyldecalin) (0.7 mL/0.2 mL, biphasic), 1mol % 7;^CD 2 Cl 2 /perfluoro(methyldecalin) (0.5 mL/0.2 mL, biphasic), 1mol % 7.…”

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confidence: 99%

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An Analogue of Grubbs Third‐Generation Catalyst with Fluorophilic Pyridine Ligands: Fluorous/Organic Phase‐Transfer Activation of Ring‐Closing Alkene Metathesis

Balogh

Hlil

et al. 2015

ChemCatChem

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= 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene, R f8 = (CF 2 ) 7 CF 3 ]w as prepared from the fluorous pyridine 3,5-NC 5 H 3 (CH 2 CH 2 R f8 ) 2 (2.1 equiv.) and the pyridine complex(H 2 IMes)(NC 5 H 5 ) 2 (Cl) 2 Ru(= CHPh). 3,5-NC 5 H 3 (CH 2 CH 2 R f8 ) 2 was synthesized by aH eck reaction of 3,5-dibromopyridine and the fluorousa lkene H 2 C=CHR f8 [2.4 equiv. ;P d(OAc) 2 (cat.), n-Bu 4 N + Br À /NaOAc( 2.0 equiv.)],f ollowed by hydrogenation. The catalyst shows dramatic rate accelerations in the ring-closing metatheses of a,w-dienes under fluorous/organic liquid/ liquid biphasic conditions [e.g.,p erfluoro(methyldecalin)/ CD 2 Cl 2 ]r elative to rates under monophasic organic conditions (e.g.,C D 2 Cl 2 ). These catalysts require initial dissociation of the pyridine ligands to generate the active species, which can either combine with an alkene (productive) or recombine with ap yridine (unproductive). In the case of (H 2 IMes)[3,5-NC 5 H 2 (CH 2 CH 2 R f8 ) 2 ] 2 (Cl) 2 Ru(= CHPh), fluorophilic 3,5-NC 5 H 3 (CH 2 CH 2 R f8 ) 2 transfers to the fluorousp hase, in accord with its CF 3 C 6 F 11 /toluene partition coefficient [93.9:6.1 vs. 39.8:60.2 for (H 2 IMes)[3,5-NC 5 H 3 (CH 2 CH 2 R f8 ) 2 ] 2 (Cl) 2 Ru(= CHPh)], which decreases the fraction of unproductive events.Scheme1.Phase-transfer activationo fcatalysts:general principles and phosphine-containing metathesis catalystss tudied previously.Cy= cyclohexyl, Mes = 2,4,6-trimethylphenyl.[a] Dr.

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“…[2] The cooperativity effect engendered by dinuclear catalysts has been extensively investigated (Scheme 1, I). [6] By installing ap olyethylene glycol moiety into the salicylaldiminato ligand, Do et al showed that the properties of the corresponding nickel catalysts could be tuned using alkali cations during ethylene polymerization (Scheme 1, VI). [4] Theolefin polymerization process was modulated by the introduction of al igand second coordination sphere that interacted weakly with the growing polymer chain or the metal center (Scheme 1, III and IV).…”

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Influence of Polyethylene Glycol Unit on Palladium‐ and Nickel‐Catalyzed Ethylene Polymerization and Copolymerization

Zhang

Chen

2017

Angewandte Chemie

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The transition-metal-catalyzed copolymerization of olefins with polar functionalized co-monomers represents am ajor challenge in the field of olefin polymerization. It is extremely difficult to simultaneously achieve improvements in catalytic activity,p olar monomer incorporation, and copolymer molecular weight through ligand modifications.Herein we introduce ap olyethylene glycol unit to some phosphinesulfonate palladium and nickel catalysts,a nd its influence on ethylene polymerization and copolymerization is investigated. In ethylene polymerization, this strategy leads to enhanced activity,catalyst stability,and increased polyethylene molecular weight. In ethylene copolymerization with polar monomers, improvements in all copolymerization parameters are realized. This effect is most significant for polar monomers with hydrogen-bond-donating abilities.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

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Activation of Single-Component Nickel(II) Polyethylene Catalysts via Phase Transfer of Fluorous Phosphine Ligands

Cited by 23 publications

References 30 publications

Phase‐Transfer Activation of Transition Metal Catalysts

Phase‐Transfer Activation of Transition Metal Catalysts

An Analogue of Grubbs Third‐Generation Catalyst with Fluorophilic Pyridine Ligands: Fluorous/Organic Phase‐Transfer Activation of Ring‐Closing Alkene Metathesis

Influence of Polyethylene Glycol Unit on Palladium‐ and Nickel‐Catalyzed Ethylene Polymerization and Copolymerization

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