Eine einfache Synthese von Polyacetylen‐Latices in wässrigem Medium

Krause, Jens O.; Zarka, M. Tobias; Anders, Udo; Weberskirch, Ralf; Nuyken, Oskar; Buchmeiser, Michael R.

doi:10.1002/ange.200352637

Cited by 71 publications

(93 citation statements)

References 34 publications

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“…In fact, 2 in particular is highly active in the polymerization of DEDPM even at room temperature to form poly(DEDPM) consisting of 95 % five-membered rings, that is, poly(cyclopent-1-enevinylene)s, and 5 % of six-membered rings, that is, poly(cyclohex-1-ene-3-methylidene)s, as evidenced by the two different chemical shifts (d = 171.6 and 170.5 ppm, respectively) of the carbonyl carbon atoms of the two repeat units in the 13 C NMR spectrum (Figures 3 and 4). [77] Unlike with other Ru-based metathesis catalysts, [54,57] the polymerization does not proceed in a living [78] manner: it yields poly(DEDPM) with M n = 20 000 and a PDI of 1.9-2.3.…”

Section: Resultsmentioning

confidence: 96%

Novel Metathesis Catalysts Based on Ruthenium 1,3‐Dimesityl‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidenes: Synthesis, Structure, Immobilization, and Catalytic Activity

Yang

Mayr

Wurst

et al. 2004

Chemistry A European J

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178

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The synthesis of novel ruthenium-based metathesis catalysts containing the saturated 1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene ligand, that is, [RuCl2(NHC)[=CH-2-(2-PrO)-5-NO(2)-C6H3]] (1) and [Ru(CF3COO)2(NHC)[=CH-2-(2-PrO)-5-NO2-C6H3]] (2) (NHC=1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene) is described. Both catalysts are highly active in ring-closing metathesis (RCM) and ring-opening cross-metathesis (ROCM). Compound 1 shows moderate activity in enyne metathesis. Compound 2 is not applicable to enyne metathesis since it shows high activity in the cyclopolymerization of diethyl dipropargylmalonate (DEDPM). Poly(DEDPM) prepared by the action of 2 consists of 95% five-membered rings, that is, poly(cyclopent-1-enevinylene)s, and 5 % of six-membered rings, that is, poly(cyclohex-1-ene-3-methylidene)s. The polymerization proceeds in a nonliving manner and results in polyenes with broad polydispersities (1.9< or =PDI< or =2.3). Supported analogues of 2 were prepared by immobilization on hydroxymethyl-Merrifield resin and a monolithic support derived from ring-opening-metathesis polymerization (ROMP). Catalyst loadings of 1 and 2.5%, respectively, were obtained. Both supported versions of 2 showed excellent reactivity. With 0.24-2% of the supported catalysts, yields in RCM and ROCM were in the range of 76-100%. Leaching of ruthenium was low and resulted in Ru contaminations of the products of less than 0.000014% (0.14 ppm).

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Section: Resultsmentioning

confidence: 96%

Novel Metathesis Catalysts Based on Ruthenium 1,3‐Dimesityl‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidenes: Synthesis, Structure, Immobilization, and Catalytic Activity

Yang

Mayr

Wurst

et al. 2004

Chemistry A European J

Self Cite

178

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“…[13,14] Generally, both selectivity and reactivity of Grubbs-or GrubbsHoveyda-type initiators is governed by the nature of the Nheterocyclic carbene (NHC), [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] the alkylidene, [31][32][33][34][35][36][37][38][39][40][41][42] or the (pseudo)halide ligands. [43][44][45][46][47][48][49][50][51][52][53] We recently reported on an alternative system for the synthesis of alternating copolymers based on Grubbs-type initiators containing an unsymmetrical, chiral NHC. [29] In this contribution, we investigated the scope and limitations of this concept by using a series of Ru-alkylidenes based on unsymmetrical NHCs.…”

Section: Introductionmentioning

confidence: 99%

Alternating Ring‐Opening Metathesis Copolymerization by Grubbs‐Type Initiators with Unsymmetrical N‐Heterocyclic Carbenes

Lichtenheldt

Wang

Vehlow

et al. 2009

Chemistry A European J

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A series of Ru(IV)-alkylidenes based on unsymmetrical imidazolin-2-ylidenes, that is, [RuCl(2){1-(2,4,6-trimethylphenyl)-3-R-4,5-dihydro-(3H)-imidazol-1-ylidene}(CHPh)(pyridin)] (R = CH(2)Ph (5), Ph (6), ethyl (7), methyl (8)), have been synthesized. These and the parent initiators [RuCl(2)(PCy(3)){1-(2,4,6-trimethylphenyl)-3-R-4,5-dihydro-(3H)-imidazol-1-ylidene}(CHC(6)H(5))] (R = CH(2)C(6)H(5) (1), C(6)H(5) (2), ethyl (3)) were used for the alternating copolymerization of norborn-2-ene (NBE) with cis-cyclooctene (COE) and cyclopentene (CPE), respectively. Alternating copolymers, that is, poly(NBE-alt-COE)(n) and poly(NBE-alt-CPE)(n) containing up to 97 and 91% alternating diads, respectively, were obtained. The copolymerization parameters of the alternating copolymerization of NBE with CPE under the action of initiators 1-3 and 5-8 were determined by using both a zero- and first-order Markov model. Finally, kinetic investigations using initiators 1-3, 6, and 7 were carried out. These revealed that in contrast to the 2nd-generation Grubbs-type initiators 1-3 the corresponding pyridine derivatives 6 and 7 represent fast and quantitative initiating systems. Hydrogenation of poly(NBE-alt-COE)(n) yielded a fully saturated, hydrocarbon-based polymer. Its backbone can formally be derived by 1-olefin polymerization of CPE (1,3-insertion) followed by five ethylene units and thus serves as an excellent model compound for 1-olefin polymerization-derived copolymers.

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“…[5] The chloride-free versions of the nitro [6a] and asarone [6b] Hoveydatype catalysts were reported by Buchmeiser and co-workers to be advantageous in the living polymerization of some 1,6-heptadiynes. [7] Hoveyda and co-workers introduced various chiral phenol-tethered alkylidenes to give excellent catalysts for enantioselective metathesis.…”

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confidence: 99%

A Dormant Ruthenium Catalyst Bearing a Chelating Carboxylate Ligand: In Situ Activation and Application in Metathesis Reactions

et al. 2007

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Eine einfache Synthese von Polyacetylen‐Latices in wässrigem Medium

Cited by 71 publications

References 34 publications

Novel Metathesis Catalysts Based on Ruthenium 1,3‐Dimesityl‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidenes: Synthesis, Structure, Immobilization, and Catalytic Activity

Novel Metathesis Catalysts Based on Ruthenium 1,3‐Dimesityl‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidenes: Synthesis, Structure, Immobilization, and Catalytic Activity

Alternating Ring‐Opening Metathesis Copolymerization by Grubbs‐Type Initiators with Unsymmetrical N‐Heterocyclic Carbenes

A Dormant Ruthenium Catalyst Bearing a Chelating Carboxylate Ligand: In Situ Activation and Application in Metathesis Reactions

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