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.

Piperidine as ancillary ligand in the novel [RuCl2(PPh3)2(piperidine)] complex for metathesis polymerization of norbornene and norbornadiene

Abstract: Reaction between [RuCl 2 (PPh 3 ) 3 ] and piperidine (pip) gives the novel [RuCl 2 (PPh 3 ) 2 (pip)] complex, which quantitatively polymerizes norbornene (NBE) via ring opening metathesis polymerization for less than 1 min at RT, in the presence of 5 μL of ethydiazoacetate. An M w / M n value of 1.05 is obtained if amounts of norbornene are added in several batches up to the [NBE]/[Ru] = 5.000. Norbornadiene is polymerized with 48% yield for 5 min at RT. The precursor complex gives only 63% of polynorbornene and 6% of polynorbornadiene for 5 min at 50 °C. 31 P{ 1 H} NMR analyses indicate that the new complex does not undergo dimerization in solution as it occurs in the case of the precursor complex. It is proposed that the presence of the piperidine is appropriated in enhancing the rate of reaction and controlling the ruthenium metathesis catalysis via a highly active five-coordinated mononuclear Ru(II) complex.

Ring-Opening Metathesis Polymerization Using Alkenyl Sulfides as Chain-Transfer Agents: Efficient Routes to Unsymmetrical Poly(norbornene)-Based Macroinitiators Bearing a Terminal Hydroxy Group

Abstract: Convenient routes to hydroxy-terminated poly(norbornene)s (PNBEs) have been developed. Hydroboration of PNBEs bearing a terminal vinyl group with 9-BBN followed by oxidation with H2O2/NaOH forms hydroxy-terminated PNBEs in high yields. The parent PNBEs are prepared by ring-opening metathesis polymerization (ROMP) of norbornene using vinylic sulfides as chain-transfer agents (CTAs). On the other hand, ROMP of norbornene using (Z)-1-phenylthio-1-propen-3-ol as a CTA causes one-step synthesis of ω-hydroxy-terminated PNBE, where the molecular weight of polymer depends linearly on the initial feed ratio of CTA to monomer. Similarly, ROMP reactions using (Z)-1-phenylthio-1-propen-3-ols having bromo, amino, and 4-(chloromethyl)benzamido substituents at the para position of the phenyl group as CTAs afford the corresponding α,ω-heterodifunctionalized (heterotelechelic) PNBEs. The resulting PNBEs serve as macroinitiators for anionic ring-opening polymerization (AROP) of e-caprolactone and atom-transfer radical poly...

Ethene-norbornene copolymerizations using two different homogeneous metallocene catalyst systems and investigations of the copolymer microstructure

Abstract: Ethene–norbornene copolymerizations were carried out at various ethene pressures by using the homogeneous catalyst systems iPr[(3-iPr-Cp)Ind]ZrCl2/MAO and rac-iPr[Ind]2ZrCl2/MAO. The copolymer microstructures were analyzed by 13 C NMR spectroscopic investigations. On the basis of the obtained results, it could be concluded that copolymers generated with the metallocene iPr[(3-iPr-Cp)Ind]ZrCl2 contain norbornene microblocks with a maximum length of two norbornene units in spite of high norbornene excess in the norbornene and ethene feedstock composition. In the microstructures of copolymers generated with the metallocene rac-iPr[Ind]2ZrCl2 norbornene microblocks with a length of three norbornene units have been detected. Results have shown that the amount of norbornene triblocks in the copolymer chain as well as the stereochemical connection of the norbornene triblocks depends on the monomer concentration and the polymerization temperature.

Novel multifunctional polymeric materials with predominant cis microstructures derived from α‐norbornenyl macromonomer and stable macroinitiator via ring‐opening metathesis polymerization and atom transfer radical polymerization

Abstract: Novel star-like polymeric materials with high cis content could be obtained by using α-norbornenyl macromonomers and highly stable macroinitiators derived from an active norbornene derivative [5-(2-bromo-2-methylpropionylaminomethyl)bicyclo[2.2.1]hept-2-ene (NBBrMPAM)], which was synthesized by the reaction of norbornene methylene amine and 2-bromo-2-methylpropionyl bromide. The α-norbornenyl macromonomer (NBPMMA), which is polymethyl methacrylate containing norbornenyl end group, was prepared by atom transfer radical polymerization (ATRP) using NBBrMPAM as an initiator. Star-like polynorbornene with high cis microstructure (cis/trans = 72/28) was obtained directly by ring-opening metathesis polymerization of NBPMMA macromonomer having number molecular weight (Mn) as low as 6.39 × 103. Random ring-opening metathesis copolymerization of NBPMMA and norbornene derivative containing carbazole group (NBCbz) was carried out at 25 °C by using Ru catalyst [(Cy3P)2Cl2Ru = CHPh, Cy = cyclohexyl, Ph = phenyl]. High cis (cis/trans = 63/37) organo-soluble star-like random poly(NBPMMA-co-NBCbz) was successfully obtained with high number-average molecular weight (Mn) of 4.76 × 104 and molecular weight distribution polydispersity index of 1.78. Organo-soluble comb-shaped copolymers with MMA could be successfully obtained using ATRP macroinitiator [poly(HNBBrMPAM)] in diluted macroinitiator solution with a concentration less than 3.64 × 10−2 mol.L−1. This is the first ever attempt to prepare novel star-like organo-soluble polymeric materials with high cis microstructure via the combination of ring-opening metathesis polymerization and ATRP. Multimodification could be considered to be carried out by using the functional bromo group at the end of side chains. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3382–3392, 2006