1.5- cyclooctadiene polymerization activity

The presence of halogen atoms appears to exert little, if any, effect on catalyst activity, but it can influence the course of the metathesis reaction. Vinylic halides are unreactive, as exemplified by the ring-opening polymerization of l-chloro-l,5-cyclooctadiene, which afforded a perfectly alternating copolymer of butadiene and chloroprene (7/2) via polymerization exclusively through the unsubstituted double bond. 

A glass reactor was charged with W-(2,6-diisopropylphenyl)-2-(2,6-diisopropyl-phenylimino)propanamide-benzyltrimethylphosphine nickel (20 pmol) in toluene, bis(l,5-cyclooctadiene)-nickel (50p,mol) in toluene, and 5-norbomen-2-ol (4.49 mmol) were dissolved in toluene, and additional toluene (18.45 g) added so that the total volume of the toluene solution was 30 ml. The glass reactor was then sealed and ethylene continuously fed into the reactor at 100 psi and the mixture stirred for 20 minutes at 20°C. Acetone was then added to quench the polymerization and die precipitated polymer isolated by filtration, dried, and 0.518 g of product isolated. The activity of the catalyst was 105 kg mol lh 1. 

The complex is also active in ring-opening metathesis polymerization of 1,5-cyclooctadiene (COD), where the ruthenium—carbene bond is now the initiating point. Therefore, a mixture of MMA and COD undergoes a dual or tandem living polymerization of both monomers to generate block copolymers of COD and MMA, which can be converted into ethylene-block-MMA copolymers on subsequent hydrogenation, also catalyzed by the complex. 

Such polycondensation dehalogenation reactions remain a commonly employed route to poly thiophene, and a range of solvents, halogenothiophene substrates, and other metal-based catalysts have been examined, as recently reviewed.29 For example, the reaction of 2,5-dibromothiophene with Ni(cyclooctadiene)2 and triphenylphosphine in DMF leads to an almost quantitative yield of polythiophene.30 Solid-state 13C NMR studies confirm exclusive 2,5-coupling of the thiophene repeat units in the polymeric product. The 2,5-dichlorothiophene monomer is less active as a substrate in such reactions however, the corresponding 2,5-diiodothiophene is reported to be a good substrate.31... 

The activity and selectivity of the bound Wilkinson catalyst parallels in many ways the homogeneous system. Terminal olefins are hydrogenated more rapidly than internal olefins, cw-olefins react faster than rran5-olefins, and olefins are reduced faster than acetylenes.There were some differences with the sterically hindered l(7)-p-menthene the polymeric catalyst, for example, produced appreciably more isomerized material. Furthermore, the attached complex was more selective in the hydrogenation of 1,3-cyclooctadiene. 

When conducting the ROMP of norbornene or cyclooctadiene in miniemulsions [82], two approaches were followed (i) addition of a catalyst solution to a miniemulsion of the monomer and (ii) addition of the monomer to a miniemulsion of Grubbs catalyst in water. With the first approach it was possible to synthesize stable latexes with a high conversion, whereas for the second approach particles of >400 nm were created, without coagulum, but with 100% conversion. Subsequently, a water-soluble ruthenium carbene complex [poly(ethylene oxide)-based catalyst] was prepared and used in the direct miniemulsion ROMP of norbornene [83], whereby particles of 200-250 nm were produced. The catalytic polymerization of norbornene in direct miniemulsion was also carried out in the presence of an oil-soluble catalyst generated in situ, or with a water-soluble catalyst [84] the reaction was faster when using the oil-soluble catalyst. Helical-substituted polyacetylene could be efficiently polymerized in direct miniemulsion to yield a latex with particles that ranged between 60 and 400 nm in size, and which displayed an intense circular dichroism [85] that increased as the particle size decreased. The films were prepared from dried miniemulsion latexes that had been mixed with poly(vinyl alcohol) (PVA) in order to conserve the optical activity. 

The emulsion polymerization of norbornene and cyclooctadiene in water was catalyzed by well-defined, water-soluble Ru-alkylidene metathesis catalysts (such as [RuCl2(TPPTS)2(=CHC02Et)] in the presence of surfactants. Well-controlled polynorbornene latexes were obtained with particle sizes in the range of 50-100 nm (194). The easily available water-soluble allenylidene complex [RuCl2(TPPMS)2(=C=CH—CeHs)] was found catalytically active in the crossmetathesis of methylacrylate with cyclopentene in biphasic mixtures of acidic water and diethyl ether to give C12H19CO2CH3 in 42% yield (195). 

One of the key technologies needed to make cyclic conjugated diene polymers useful is an expansion of monomer availability. Presently, neither 1,3-cycloheptadiene nor 1,3-cyclooctadiene has been coordinatively polymerized, even with highly active cationic Ni complexes. The polymerization of functionalized CHDs is, so far, limited to ANiTFA. In order to provide processability and functionality to cyclic conjugated diene polymers, these problems must be overcome. The progress of transition metal-catalyzed polymerization may make this possible in the near future. 

The kinetics of the ADMET reaction is not amenable to study by many traditional means, as these polymerizations are mostly conducted in bulk. The most effective way to measure the kinetics of the polymerization is to monitor the volume of evolved ethylene. This technique has been used to probe the difference in activity between [Mo] 2 and [Ru]l for ADMET polymerization of 1,9-decadiene [37]. At 26 °C in bulk monomer, [Mo] 2 promotes ADMET polymerization of 1,9-decadiene at a rate approximately 24 times that of [Ru]l. Additionally, [Mo] 2 polymerizes 1,5-hexadiene 1.7 times faster than 1,9-decadiene, while [Ru]l only cyclodimerizes 1,5-hexadiene to 1,5-cyclooctadiene. Monomers with coordinating functionality, specifically ethers and sulfides, were also investigated. Predictably, these monomers did not undergo polymerization as rapidly as hydrocarbon monomers however, this difference was dramatically more pronounced with [Ru]l than with [Mo]2. In fact, the dialkenyl sulfide monomers that were studied completely shut down the polymerization with [Ru]l, whereas the catalytic activity of [Mo]2 was only slightly lowered. This reduction in polymerization rate is most likely due to coordination of the heteroatom to the vacant coordination site of [Ru] 1, following phosphine dissociation. This reversible coordination of heteroatoms to the ruthenium complex likely occurs both intramolecularly and intermolecularly. Conversely, the steric bulk of the ligands in [Mo] 2 makes it less likely to intramolecularly form a coordinate complex, despite molybdenum being far more electrophilic than ruthenium. 

Nickel compounds can also be employed as catalysts [161-170]. A three-component system consisting of nickel naphthenate, triethyl-aluminum, and boron trifluoride diethyletherate is used technically. The activities are similar to those of cobalt systems. The molar Al/B ratio is on the order of 0.7 to 1.4. Polymerization temperatures range from -5 to 40 °C. On a laboratory scale the synthesis of 1,4-polybutadiene with allylchloronickel giving 89% cis, 7.7% trans, and 3.4% 1,2-structures is particularly simple [8]. In nickel compounds with Lewis acids as cocatalysts, complexes with 2,6,10-dodecatriene ligands are more active than those with 1,5-cyclooctadiene (Table 4) [171]. 

The catalysts 4a-d show no activity at room temperature but are stable for months in solution. We tested their activity in the ring-opening metathesis polymerization (ROMP) of 1,5-cyclooctadiene (COD) at 90°C in toluene-d8 (Figure 2). The Schiffbase catalysts 4a-d and 5c are clearly less active than... 

Various unicomponent catalysts based on n complexes of transition metals from groups IV-VII of the Periodic Table, e.g., (7i-allyl)4Zr, (7i-allyl)3Cr, (ti-allyl)2Ni, (7i-allyl)3Co, (7i-allylPdX)2, (7i-allylRhX)2, have been found to be very active in polymerization of a large number of cycloolefins like cyclobutene, cyclopentene, cyclooctene, cyclooctadiene and norbornene [36], Some of these catalysts induce polymerization of the cycloolefin totally to vinyl polymers while other catalysts of this class give preferentially vinylic polymers accompanied in a large extension by ring-opened polymers. 

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