Cyclooctenes ring-opening metathesis polymerization

Ring-opening metathesis polymerization was conducted by Verpoort et al. (4) using cyclooctene with a ruthenium Schiff base complex, (V), and proceeded with a monomer-to-catalyst ratio of 150,000 1, respectively. 

M.A. Hillmyer, W.R. Laredo, and R.H. Grubbs, Ring-opening metathesis polymerization of functionalized cyclooctenes by a ruthenium-based metathesis catalyst, Macromolecules, 28(18) 6311-16,1995. 

The synthesis of polyoctenamer has been commercialized by Huels.150 In contrast with the transformation of cyclooctene to 1,9-decadiene [Eq. (12.31)], homogeneous catalyst compositions, such as WClg + EtAlCl2, are used to promote ring-opening metathesis polymerization of cyclooctene. A polymer of narrow molecular-weight distribution with high trans content (55-85%) called Vestenamer is produced and used as blend component in different rubbers and thermoplastics. 

Recently, Dai, Su, and coworkers synthesized the block copolymer of polythiophene and polypyridine from the vinyl-terminated polythiophene (Scheme 102) [336]. Meijer and coworkers used an allyl-terminated polythiophene to synthesize a block copolymer of poly(3-hexylthiophene) and polyethylene the ring-opening metathesis polymerization of cyclooctene in the presence of the allyl-terminated polythiophene was followed by hydrogenation (Scheme 103) [337]. 

Dimerization of butadiene is used for the selective formation of 1,5-cyclo-octadiene (1,5-COD), which on selective hydrogenation gives cyclooctene. By ring-opened metathesis polymerization of cyclooctene a specialty polymer is obtained (see Section 7.6.1). Hulls sells this polymer as Vestenamer . 

Metathesis of alkenes is essentially a class of reactions where an interchange of C atoms between pairs of double bonds takes place. A few representative examples are shown by the reactions listed in Fig. 7.10. The industrial use of metathesis reactions so far has been limited mainly to exchange metathesis (Fig. 7.10, top, backward reaction) as in the SHOP process, and ring-open metathesis polymerization (ROMP). As already mentioned (Section 7.5), Vas-tenamer is a polymer made by Hulls by ROMP from cyclooctene. Similarly, the polymer from norborene by ROMP is manufactured by CdF Chemie and is sold by the trade name of Norsorex . 

Figure 7.12 Ring-opened metathesis polymerization (ROMP) of cyclooctene. Note that ROMP could be initiated with any M=CR2, and for a living polymer the end group will be CH=CR2.

A screening of ruthenium(II) carboxylates and several ruthenium(II) chloride complexes has identified tetrakis(trifluoroacetato)diruthenium as an excellent catalyst for the cyclo-propanation of cyclooctene with ethyl diazoacetate (60°C, excess of alkene, 0.75 mol% of catalyst yield of ethyl bicyclo[6.1,0]nonane-9-carboxylate 99% endojexo 1.65)." With several other ruthenium(II) complexes, ring-opening metathesis polymerization of cyclooctene competes strongly with the cyclopropanation reaction. 

Cyclic olefins undergo a very unusual type of ring-opening polymerization in the presence of certain transition metal catalysts [253-257]. This is illustrated in Eq. (90) for the ring-opening metathesis polymerization (ROMP) [255] of cyclooctene to form polyoctenamer. Quite surprisingly, the double bond is maintained in the polymer, i.e., it is not a normal addition polymer. The generally accepted mechanism for these... 

P. H. Henna and R. C. Larock, Rubbery thermosets by ring-opening metathesis polymerization of a functionalized castor oil and cyclooctene , Macromol Mater Eng, 2007, 292,1201-9. 

The aim of this work is to asses tentatively the synthetic value of ultrasound mediated metathesis reactions. To our knowledge no research has been to date reported in this specific ultrasound application domain. In particular, we chose to explore the effects of an ultrasonic field on the preparation of tungsten-based metathesis catalysts and thereby ring-opening metathesis polymerization of two cycloolefins, cyclooctene and cyclododecene. 

Alternatively, poly(3-hexylthiophene)-f>-polystyrene was prepared by anionic polymerization [247]. Mei-jer and co-workers reported the use of allyl-terminated regioregular poly(3-hexylthiophene) as a chain transfer agent in ring-opening metathesis polymerization (ROMP) of cyclooctene. Subsequent hydrogenation yielded poly(3-hexylthiophene)-f>-polyethylene [248]. 

The partial hydrogenation of multiple bonds includes chemical reactions of industrial interest for example, the partial hydrogenation of benzene to cyclohexene used to synthesize several compounds, from which the main is nylon production, the partial hydrogenation of 1,5-cyclooctadiene (COD) to cyclooctene (COE), which is an important industrial intermediate product for manufacturing special polymers such as poly-octenamers via ring-opening metathesis polymerization, which is used as a modifier in mbbers and thermoplastics (Sato, Aoki, Noyori, 1998 Rylander, 1985 Schmidt Schomacker, 2007). 

Table 7.1 Gas-phase, Gibbs free energies at 298 K of the intermediates and transition states in the ring-opening metathesis polymerization (ROMP) of norbornene, cyclopentene, cycloheptene, and Z-cyclooctene. Adapted from Ref [39] . ...

Stumpf, A.W., Salve, E., Demonceau, A., Noels, A.F., Rutheiiiimi-based catalysts for the ring-opening metathesis polymerization of low-strain cyclic olefins and of functionalised derivatives of norbomene and cyclooctene, Chem. Commua 1995, 1127-1128. 

Abstract Several routes to access ruthenium (Ru)-vinylidene complexes are described, the majority of which employ alkynes and a Ru source as the starting materials. The successful application of Ru-vinylidenes as efficient pre-catalysts for the synthesis of carbocyclic and heterocyclic compoimds by ring-closing metathesis (RCM) of a, -dienes, and in the synthesis of polymers by ring-opening metathesis polymerization (ROMP) of cyclooctene, norbomene, 5-substituted norbomene, and dicyclopentadiene is fully illustrated. Relevant aspects concerning the activity and selectivity of this type of Ru complexes in metathesis reactions are highlighted. 

Keywords cyclooctene, homogeneous catalysis, imidazole, ortto-metallation, ring-opening metathesis polymerization (ROMP), triazole... 

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