Topic
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.
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TL;DR: The glass transition temperature of norbornene/ethene copolymers exceeds 130°C as discussed by the authors, which is the glass transition point of cyclopentene with propene.
Abstract: With homogenous catalysts on the basis of chiral metallocenes and methylaluminoxane it has become possible to polymerize cyclic olefins like cyclobutene, cyclopentene or norbornene. No ring opening reaction occurs. The crystalline polycycloalkenes show extremly high melting points between 400 and 600°C. Copolymers of cyclopentene with propene are amorphous. They have a low molecular weight and glass transition point. On the other hand the glass transition temperature of norbornene/ethene copolymers exceeds 130°C. These copolymers could be used as materials for optical discs and fibers.
261 citations
TL;DR: The reaction mechanism of olefin metathesis by ruthenium carbene catalysts is studied by gradient-corrected density functional calculations (BP86) and the most likely dissociative mechanism with trans Olefin coordination is investigated.
Abstract: The reaction mechanism of olefin metathesis by ruthenium carbene catalysts is studied by gradient-corrected density functional calculations (BP86). Alternative reaction mechanisms for the reaction of the “first-generation” Grubbs-type catalyst (PCy3)2Cl2RuCH2 (1) for the reaction with ethylene are studied. The most likely dissociative mechanism with trans olefin coordination is investigated for the metathesis reaction between the “first-” and the “second-generation” Grubbs-type catalysts 1 and (H2IMes)(PCy3)Cl2RuCH2 (2) with different substrates, ethylene, ethyl vinyl ether, and norbornene, and a profound influence of the substrate is found. In contrast to the degenerate reaction with ethylene, the reactions with ethyl vinyl ether and norbornene are strongly exergonic by 8−15 kcal/mol, and this excess energy is released after passing through the metallacyclobutane structure. While the metallacyclobutane is in a deep potential minimum for degenerate metathesis reactions, the energy barrier for the [2+2] cy...
261 citations
TL;DR: In this article, a comparison of different titania-silica catalysts for cyclohexene, cyclodecene, norbornene and limonene epoxidation was performed using FTIR and UV-vis spectroscopy.
256 citations
TL;DR: A Pd and norbornene-catalyzed ortho-arene amination via Catellani-type C-H functionalization is reported, which gives complementary site selectivity at the Ortho- instead of ipso-position of aryl halides.
Abstract: A Pd and norbornene-catalyzed ortho-arene amination via Catellani-type C–H functionalization is reported. Aryl halides are used as substrates; N-benzoyloxyamines and isopropanol are employed as the amine source (oxidant) and reductant respectively. Examples are provided in 50–99% yields with high functional group tolerance. This method gives complementary site selectivity at the ortho- instead of ipso-position of aryl halides.
252 citations
TL;DR: 2-Carbomethoxynorbornene is identified as a more effective transient mediator to promote a Pd(II)-catalyzed meta-C(sp(2))-H alkylation of amides with various alkyl iodides as well as arylation with previously incompatible aryl iodide.
Abstract: 2-Carbomethoxynorbornene is identified as a more effective transient mediator to promote a Pd(II)-catalyzed meta-C(sp2)–H alkylation of amides with various alkyl iodides as well as arylation with previously incompatible aryl iodides. The use of a tailor-made quinoline ligand is also crucial for this reaction to proceed.
240 citations