References of "Noels, Alfred"
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See detailRuthenium alkylidenes : a new class of catalysts for Kharasch addition and controlled radical polymerisation of vinyl monomers
Richel, Aurore ULg; Delfosse, Sébastien; Demonceau, Albert ULg et al

Poster (2002)

Air-stable and readily available ruthenium benzylidene complexes of the general type [RuCl2(=CHPh)(L)(L’)] (L, L’ = PCy3 and/or N-heterocyclic carbene) constitute a new class of catalyst precursors for ... [more ▼]

Air-stable and readily available ruthenium benzylidene complexes of the general type [RuCl2(=CHPh)(L)(L’)] (L, L’ = PCy3 and/or N-heterocyclic carbene) constitute a new class of catalyst precursors for atom-transfer radical polymerisation (ATRP) of methyl methacrylate and styrene, and provide an unprecedented example for the involvement of ruthenium alkylidenes in radical reactions. They promote the polymerisation of various monomers with good to excellent yields, and in a controlled way with methyl methacrylate and styrene. The ligand L (PCy3 and/or N-heterocyclic carbene) turned out to play a particularly important role in determining the rate of the polymerisations. A similarly pronounced influence is exerted by the substituents on the N-heterocyclic carbene. Our results indicate that the catalysts decompose quickly under ATRP conditions, and polymerisations are mediated by both [RuCl2(=CHPh)-(L)(L’)] complexes and ruthenium species bereft of the benzylidene moiety. In addition, investigation on the reaction of metathesisable olefins such as styrene in the presence of carbon tetrachloride also exemplify the dual activity of ruthenium alkylidene complexes for radical reactions and olefin metathesis. [less ▲]

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See detailNew in situ generated ruthenium catalysts bearing N-heterocyclic carbene ligands for the ring-opening metathesis polymerization of cyclooctene
Delaude, Lionel ULg; Szypa, Magdalena; Demonceau, Albert ULg et al

in Advanced Synthesis & Catalysis (2002), 344(6-7), 749-756

New 1,3-diarylimidazol(in)ium chlorides bearing phenyl, 1-naphthyl, 4-biphenyl, 2-tolyl, 2,6-dimethylphenyl, and 3,5-dimethylphenyl substituents were synthesized. They were combined with [RuCl2 (p-cymene ... [more ▼]

New 1,3-diarylimidazol(in)ium chlorides bearing phenyl, 1-naphthyl, 4-biphenyl, 2-tolyl, 2,6-dimethylphenyl, and 3,5-dimethylphenyl substituents were synthesized. They were combined with [RuCl2 (p-cymene)](2) and potassium tert-butoxide or sodium hydride to generate the corresponding ruthenium-N-heterocyclic carbene complexes in situ. Catalyst precursors derived from imidazol(in)ium salts bearing the 2,4,6-trimethylphenyl (mesityl) and the 2,6-diisopropylphenyl groups were also prepared. The catalytic activity of all these species in the photoinduced ring-opening metathesis polymerization of cyclooctene was investigated. The C4-C5 double bond in the imidazole ring of the N-heterocyclic carbene ligands was not crucial to achieve high catalytic efficiencies. The presence or the absence of alkyl groups on the ortho positions of the phenyl rings had a more pronounced influence. Blocking all the ortho positions was a requisite for obtaining efficient catalysts. Failure to do so probably results in the ortho-metallation of the carbene ligand, thereby altering the coordination sphere of the ruthenium active centers. [less ▲]

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See detailSynthesis and ring-opening metathesis polymerization of eight-membered unsaturated lactams and related monomers
Baran, Janusz; Bogdanska, Irena; Jan, Dominique et al

in Journal of Molecular Catalysis A-Chemical (2002), 190(1-févr Sp. Iss. SI), 109-116

Novel eight-membered ring unsaturated lactams were synthesized and tested as monomers for the ruthenium-catalyzed ring-opening metathesis polymerization (ROMP). The reaction of a N-protected cyclic ... [more ▼]

Novel eight-membered ring unsaturated lactams were synthesized and tested as monomers for the ruthenium-catalyzed ring-opening metathesis polymerization (ROMP). The reaction of a N-protected cyclic alkeneamine was also investigated. The Grubbs' benzylidene complexes RuCl2(=CHPh)(PCy3)(2) or RUCl2(=CHPh)(PCy3)(IMesH(2)) and selected ruthenium-arene species bearing either phosphine or stable Arduengo-type N-heterocyclic carbene ligands served as catalyst precursors. In most cases, isomerization of the starting materials took place and only 1-benzyl-1-aza-2-ketocyclooct-5-ene afforded a polymeric product. This polyamide was characterized by numerous analytical techniques. (C) 2002 Elsevier Science B.V All rights reserved. [less ▲]

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See detailVisible light induced ring-opening metathesis polymerisation of cyclooctene
Delaude, Lionel ULg; Demonceau, Albert ULg; Noels, Alfred ULg

in Chemical Communications (2001), (11), 986-987

Under visible light irradiation, ruthenium-arene complexes bearing N-heterocyclic carbene ligands with aryl substituents - either preformed or generated in situ - are active catalyst precursors for the ... [more ▼]

Under visible light irradiation, ruthenium-arene complexes bearing N-heterocyclic carbene ligands with aryl substituents - either preformed or generated in situ - are active catalyst precursors for the ROMP of cyclooctene already at room temperature. [less ▲]

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See detailEvaluation of ruthenium-based complexes for the controlled radical polymerization of vinyl monomers
Simal, François; Jan, Dominique; Delaude, Lionel ULg et al

in Canadian Journal of Chemistry (2001), 79(5-6), 529-535

New complexes of the type RuCl2(p-cymene)L where the ligand L is either a phosphine or a stable triazolinylidene carbene have been tested and compared to the Grubbs' benzylidene complex RuCl2(=CHPh)(PCy3 ... [more ▼]

New complexes of the type RuCl2(p-cymene)L where the ligand L is either a phosphine or a stable triazolinylidene carbene have been tested and compared to the Grubbs' benzylidene complex RuCl2(=CHPh)(PCy3)(2) as catalyst precursors for the controlled atom transfer radical polymerization (ATRP) of methyl methacrylate and of various para-substituted styrenes. Kinetic data and Hammett rho constants are reported, as well as the X-ray structure of the ortho-metallated triazolinylidene-ruthenium(II) complex RuCl(p-cymene)[1,2-phenylene[3,4-diphenyl-1H-1,2,4-triazol-1-yl-5(4H)-yl idene]]. [less ▲]

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See detailRuthenium-based catalysts for the ring-opening metathesis polymerization (ROMP) of functionalized cyclic olefins
Delaude, Lionel ULg; Jan, Dominique; Simal, François et al

in Macromolecular Symposia (2000), 153

Recent developments in Ring-Opening Metathesis Polymerization (and copolymerization) of functionalized cycloolefins with well-defined ruthenium-based initiators are summarized and illustrated with ... [more ▼]

Recent developments in Ring-Opening Metathesis Polymerization (and copolymerization) of functionalized cycloolefins with well-defined ruthenium-based initiators are summarized and illustrated with synthesis of graft copolymers, telechelic and liquid crystalline polymers, glycopolymers and unsaturated ester-functionalized oligomers. [less ▲]

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See detailSynthesis and evaluation of new RuCl2(p-cymene)(ER2R') and (eta(1):eta(6)-phosphinoarene)RuCl2 complexes as ring-opening metathesis polymerization catalysts
Jan, Dominique; Delaude, Lionel ULg; Simal, François et al

in Journal of Organometallic Chemistry (2000), 606(1), 55-64

New RuCl2(p-cymene)(ER2R') complexes (E = P, As, Sb; R, R' = H, alkyl, arylalkyl) have been synthesized and used as catalyst precursors for the ring-opening metathesis polymerization (ROMP) of cyclooctene ... [more ▼]

New RuCl2(p-cymene)(ER2R') complexes (E = P, As, Sb; R, R' = H, alkyl, arylalkyl) have been synthesized and used as catalyst precursors for the ring-opening metathesis polymerization (ROMP) of cyclooctene, cyclopentene, and norbornene. When ER2R' was a phosphinoarene, the p-cymene ligand could be displaced upon heating and tethered (eta(1):eta(6)-phosphinoarene)RuCl2 complexes were obtained. Simple thermogravimetric analysis (TGA) of the complexes provided clear-cut indication on their potential catalytic activity in ROMP. (C) 2000 Elsevier Science S.A. All rights reserved. [less ▲]

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See detailAccretion from AGB winds.
Thoul, Anne ULg; Jorissen, A.; Goriely, S. et al

in Memorie della Società Astronomica Italiana : Journal of the Italian Astronomical Society (2000), 71

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See detailHighly stereoselective ruthenium-catalyzed ring-opening metathesis polymerization of 2,3-difunctionalized norbornadienes and their 7-oxa analogues
Delaude, Lionel ULg; Demonceau, Albert ULg; Noels, Alfred ULg

in Macromolecules (1999), 32(7), 2091-2103

The ring-opening metathesis polymerization (ROMP) of 2,3-difunctionalized norbornadienes and their 7-oxa analogues catalyzed by [RuCl2(p-cymene)](2) in the presence of trimethylsilyldiazomethane (TMSD ... [more ▼]

The ring-opening metathesis polymerization (ROMP) of 2,3-difunctionalized norbornadienes and their 7-oxa analogues catalyzed by [RuCl2(p-cymene)](2) in the presence of trimethylsilyldiazomethane (TMSD) yields high-trans, highly tactic polymers. A tentative mechanism involving arene loss, carbene formation, and monomer chelation is presented. The ROMP of 2,3-dicarbomethoxynorbornadiene served as a test reaction to investigate the influence of the various experimental parameters (reaction time and temperature, nature of the solvent and catalyst, and TMSD initiation conditions). An all-trans, highly tactic (>79%) polymer was obtained under a wide variety of conditions. Strikingly, the addition of tricyclohexylphosphine had a detrimental influence on the polymerization yield and stereoselectivity. The procedure was successfully applied to various other 2,3-dicarboalkoxynorbornadienes, benzonorbornadiene, and their 7-oxa analogues. In the case of the diester monomers, an increase in the alkyl substituent size led to a decrease of the polymer trans content and tacticity. Because of the ruthenium catalyst's ready availability and marked resistance to oxygen and water, reactions were very easy to set up and to carry out. [less ▲]

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See detailAtom-transfer radical polymerization of vinyl monomers mediated by stable ruthenium-carbene complexes.
Demonceau, Albert ULg; Simal, François; Delaude, Lionel ULg et al

in Abstracts of Papers - American Chemical Society, National Meeting (1999), 218(Part 2), 289-

We reported on the exceptional efficacy of new catalytic systems based on well-defined and fully characterized [RuCl2(p-cymene)(PR3)] complexes (p-cymene = 4-isopropyltoluene) to promote the controlled ... [more ▼]

We reported on the exceptional efficacy of new catalytic systems based on well-defined and fully characterized [RuCl2(p-cymene)(PR3)] complexes (p-cymene = 4-isopropyltoluene) to promote the controlled free-radical polymerization of vinyl monomers without cocatalyst activation. It appeared that only phosphines which are both strongly basic and which possess a well-defined steric bulk presented both high catalytic activity and high control of the polymerization process. The most suitable phosphines were triisopropylphosphine and tricyclohexylphosphine (PCy3, Cy = cyclohexyl). Surprisingly, the best catalyst systems for ATRP were also the most active ones for the ring-opening metathesis polymerization (ROMP) of cycloolefins. With this in mind, [RuCl2(=CHPh)(PCy3)2], the Grubbs' ruthenium-carbene complex commonly used for olefin metathesis, was tested and found to be also highly efficient for ATRP. In this paper, we present some studies on the scope and limitations of stable ruthenium-carbene complexes as potential catalysts for the ATRP of vinyl monomers. [less ▲]

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See detailStereoselective hydrogenation of methacycline to doxycycline catalysed by rhodium-carborane complexes
Pirotte, Bernard ULg; Felekidis, Apostolos ULg; Fontaine, M. et al

in Tetrahedron Letters (1993), 34

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