Norbornene

About: Norbornene is a research topic. Over the lifetime, 5628 publications have been published within this topic receiving 104495 citations. The topic is also known as: norbornylene & norcamphene.

Process for the preparation of chemically homogenous cycloolefinic copolymers

Abstract: Chemically homogeneous cycloolefin copolymers of polycyclic olefins, for example norbornene or tetracyclododecene, with cycloolefins and/or acyclic olefins are obtained without ring opening and in high space-time yields if a catalyst system is used which comprises an aluminoxane and a stereorigid metallocene compound of an element from groups IVb to VIb, of the formula the part of the metallocene molecule formed by M and the substituents R -R having C1 symmetry or being in the meso form.

Sulfuration of the norbornene double bond

Abstract: Sulfuration par S 8 des norbornene, dicyclopentadiene, isodicyclopentadiene, norbornadiene, dihydro-1,4 methano-1,4naphtalene, aryl-2 norbornenes et sesquinorbornene: obtention dans la plupart des cas de trithiolannes-1,2,3 eventuellement avec des pentathiepannes-1,2,3,4,5. Mecanismes

Homobimetallic Ruthenium–N‐Heterocyclic Carbene Complexes: Synthesis, Characterization, and Catalytic Applications

Abstract: Two new homobimetallic ruthenium-arene complexes [(p-cymene)Ru(μ-Cl) 3 RuCl(η 2 -C 2 H 4 )(L)], where L=1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene (3a) or 1,3-bis(2,4,6-trimethylphenyl)-4,5-di-chloroimidazolin-2-ylidene (3b), were isolated in high yields upon heating a toluene solution of [RuCl 2 (p-cymene)] 2 with 1 equivalent of carbene ligand under an ethylene atmosphere. They were characterized by NMR and TGA. Their catalytic activity was investigated in the atom transfer radical polymerization of vinyl monomers. In the polymerization of methyl methacrylate, complex 3a displayed faster reaction rates than 3b and the related phosphine-based complex 2a (L=tricyclohexylphosphine), although control was more effective with the latter catalyst. When n-butyl acrylate or styrene served as monomer, a major shift of reactivity was observed between complex 2a that promoted controlled radical polymerization, and complexes 3a or 3b that favored metathetical coupling. Further homocoupling experiments with various styrene derivatives confirmed the outstanding aptitude of complex 3a (and to a lesser extent of 3b) to catalyze olefin metathesis reactions. Contrary to monometallic ruthenium-arene complexes of the [RuCl 2 (p-cymene)(L)] type, the new homobimetallic species did not require the addition of a diazo compound or visible light illumination to initiate the ring-opening metathesis of norbornene or cyclooctene. When α,ω-dienes were exposed to 3a or 3b, a mixture of cycloisomerization and ring-closing metathesis products was obtained in a non-selective way. Addition of a terminal alkyne co-catalyst enhanced the metathetical activity while completely repressing the cycloisomerization process. Thus, quantitative conversions of diethyl 2,2-diallylmalonate and N,N-diallyltosylamide were achieved within 2 h at room temperature using 2 mol% of catalyst precursor 3a and 6 mol % of phenylacetylene.