Norbomenes, ring-opening metathesis

Ring-Opening Metathesis Polymerization. Several new titanacyclobutanes have been shown to initiate living ring-opening metathesis polymerization (ROMP) systems. These have been used to make diblock and triblock copolymers of norbomene [498-66-8] (N) and its derivatives (eg, dicyclopentadiene [77-73-6] (D)) (Fig. 2) (41). 

Polycycloolefins are prepared by ring opening metathesis polymerization (ROMP) using transition metal catalysts [31], By far the most commonly studied monomer is dicyclopenta-diene (Fig. 1.7). Cycloolefins with high ring strains like norbomenes and their analogs polymerize very fast and the polymerizations are quite exothermic. Metathesis catalyst systems tend to be sensitive to the presence of polar compounds and the polymerization rates... 

II), on a mesoporous support having a hexagonal unit cell. The catalyst was used to prepare 5-norbomene and cyclooctadiene copolymers by ring-opening metathesis polymerization. 

The best known polymerization of norbomene is the ring opening metathesis polymerization. The reaction is technically applied in the Norsorex process (7). 

S. T. Nguyen, L. K. Johnson, R. H. Grubbs, and J. W. Ziller, Ring-Opening Metathesis Polymerization (ROMP) of Norbomene by a Group VIII Carbene Complex in Protic Media, J. Am. Chem. Soc. 114, 3974-3975 (1992). 

These complexes are suitable for the ring-opening metathesis polymerization of functionalized norbomenes in water,148 as well as ring-closure reactions via ethylene elimination.149 The versatility of these catalysts has given rise to extensive applications in organic synthesis,150151 including, for example, amino acid derivatives.152... 

PiccineUi [5] used (tricyclopentylphosphine)dichloro(3-methyl-butenylidene), (VI), or related cyclic derivatives, (VII), to prepared anti-fog agents, (Vlll), by coupling 2-norbomene and aUyl-terminated ohgomeric ethylene oxide using ring opening metathesis polymerization as illustrated in (VIII) below. 

The ring-opening metathesis polymerization (ROMP, cf. Section 2.3.3) of strained-ring cyclic alkenes has attracted considerable attention in recent years due to the discovery that well-characterized metallacyclobutane [24] and metal alkylidene [25] complexes catalyze the living polymerization of monomers such as norbomene. Unfortunately, these catalysts often sulfer deactivating side reactions... 

The olefin metathesis reaction has been cleverly applied to organic synthesis. In ring-opening metathesis polymerization (ROMP), a strained alkene such as norbomene is allowed to undergo olefin metathesis with itself to give a polymer. 

Scheme 4.5-7 Ring-opening metathesis polymerization of norbomene in CO2 [138,139],...

Scheme 4.7-19 Metal-catalyzed ring opening metathesis (ROMP) of norbomene (nbe) in compressed SCCO2.

The ring opening metathesis polymerization (ROMP) of norbomene and other cyclic alkenes has been studied in liquid and supercritical CO2 (Scheme 4.7-19). Polynorbomenamer (Norsorex ) has very poor solubility in CO2 and the reactions proceed as precipitation polymerizations. The mthenium salt [Ru(H20)6](Tos)2 is also virtually insoluble in pure CO2 and the results with this catalyst proved difficult to reproduce because of variations in catalyst purity and reaction mixture agitation [98]. The catalytic performance could be greatly improved by working in C02/MeOH mixtures. The microstmcture of the polymer was found to be almost identical for samples prepared in neat norbomene or in CO2 and greatly differed from that obtained in MeOH or CO2/ MeOH mixtures [99]. 

Nguyen ST, Johnson LK, Grubbs RH et al (1992) Ring-opening metathesis polymerization (ROMP) of norbomene by a group VIII carbene complex in protic media. J Am Chem Soc 114 3974-3975... 

Ring-opening metathesis polymerization Norbomene- derivative. (Nor-der.) Ir/Ru-based catalyst P(Nor-der.) b b 34-37... 

Robert (Bob) Howard Grubbs main interests in organometallic chemistry and synthetic chemistry are catalysts, notably Gmbbs catalyst for olefin metathesis and ring-opening metathesis polymerization with qrdic olefins such as norbomene. He also contributed to the development of so-called living polymerization. ... 

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