Triene polymerization

The metathesis ring-opening polymerization of COT yielded PA as a viscous liquid [67] and substituted COT was polymerized or copolymerized with the formation of soluble materials with moderate conductivity. The other original and accessible method for the production of trans-PA films is ring-opening polymerization of 7,8-bis(trifluoromethy)-tricyclo-(4,2,2,0)-deca-3,7,9-triene. Polymerization in vacuum on a flask surface treated with a catalytic solution resulted in a silvery polymer film. The flotation density of this film reaches 1.1 g/cm and becomes close to the density of PA obtained by other methods. These polymers have an amorphous structure and are completely trans-isomers. They are easily dissolved in common solvents such as acetone and chloroform. A detailed description of the synthesis can be found in Ref. 68-70. 

Related to the topochemical diene polymerization is the topochemical triene polymerization. Because dienes successfully undergo a topochemical polymerization with supramolecular structural features similar to topochemical diyne polymerization it would be anticipated that trienes would require similar supramolecular parameters as for triynes. 

COT is prepared by the polymerization of ethyne at moderate temperature and pressure in the presence of nickel salts. The molecule is non-planar and behaves as a typical cyclic olefin, having no aromatic properties. It may be catalytically hydrogenated to cyclo-octene, but with Zn and dil. sulphuric acid gives 1,3,6-cyclooclairiene. It reacts with maleic anhydride to give an adduct, m.p. 166 C, derived from the isomeric structure bicyclo-4,2,0-octa-2,4,7-triene(I) ... 

Aqueous hydrofluoric acid dissolved in acetonitrile is a good catalyst for intramolecular Diels-Alder reactions [9] This reagent promotes highly stereoselective cyclizations of different triene esters (equation 8) The use of other acids, such as hydrochloric, acetic, and trifluoroacetic acid, results in complete polymerization of the starting trienes [9] (equation 8)... 

The oligomerization of cardanol with boron trifluoride etharate as the initiator was studied in detail by Antony et al. [171]. The reaction conditions were optimized by using gel permeation chromatography as 140°C with an initiator concentration of 1%. GPC data indicate conversion of all monoene, diene, and triene components into polymer except the saturated component, indicating participation of all the unsaturated components in polymerization. It is possible that the initiation of po-... 

Cyclononatriene, the smallest cyclic [3]cumulene isolated so far, polymerizes when its solutions are concentrated57. On the other hand, several radialenes have been isolated which represent cyclodimers of seven- and eight-membered 1,2,3-trienes (Scheme 9). 

Durham route, the metathesis polymerization of 7,8-bis(trifluoromethyl)tricyclo[4.2.2.0]deca-3,7,9-triene gives a high-molecular weight soluble precursor polymer that is thermally converted to polyacetylene (equation 19.6). The precursor polymer is soluble in common organic liquids and easily purified by reprecipitation. The end product can be aligned giving a more compact material with bulk densities on the order of 1.05 —1.1 g/cm. ... 

Star and miktostar polymers have been synthesized by living cationic polymerization using dienes and trienes as coupling agents and/or multifunctional initiators [Faust and Shaffer, 1997 Hadjichristidis, et al., 1999 Hadjikyriacou and Faust, 2000 Kennedy and Jacob, 1998 Puskas et al., 2001 Sawamoto, 1991]. Multifunctional halides such as hexaiodo-methylmelamines have also been used to obtain star and comb polymers [Ryu and Hirao, 2001 Zhang and Goethals, 2001], Hyperbranched and dendritic polymers have also been studied. 

Dupont and co-workers studied the Pd-catalyzed dimerization [108] and cyclodimerization [109] of butadiene in non-chloroaluminate ionic liquids. The biphasic dimerization of butadiene is an attractive research goal since the products formed, 1,3,5-octatriene and 1,3,6-octatriene, are sensitive towards undesired polymerization, so that separation by distillation is usually not possible. These octa-trienes are of some commercial relevance as intermediates for the synthesis of fragrances, plasticizers, and adhesives. Through the use of PdCl2 with two equivalents of the ligand PPhj dissolved in [BMIM][Pp6], [BMIM][Bp4], or [BMIM][CF3S03], it was possible to obtain the octatrienes with 100 % selectivity (after 13 % conversion) (Scheme 5.2-23) [108]. The turnover frequency (TOP) was in the range of 50 mol butadiene converted per mol catalyst per hour, which represents a substantial increase in catalyst activity in comparison to the same reaction under otherwise identical conditions (70 °C, 3 h, butadiene/Pd = 1250) in THF (TOP = 6 h ). 

Oxabicyclo[3.2.0]hepta-l,4,6-triene (289), a planar Sn-electron analog of 4, has been prepared by flow pyrolysis of 288 (both cis and trans) in approximately 10% yield (>95% purity) 289 is an extremely sensitive compound, polymerizing instantaneously on exposure to oxygen. In solution, where it is stable for several days, it slowly dimerizes to give the known compound 291 the pentacyclic intermediate 290 is possibly involved. In Diels-Alder reactions, 289 behaves like an olefin with cyclopentadiene it reacts immediately to give 292. Hydrogenation occurs at the same site. ... 

In contrast to 52 (Scheme 12), diastereomer 55 (Scheme 13), because of its more exposed and highly reactive strained olefin, undergoes rapid polymerization in the presence of 4a. The less reactive Ru complex 56 [23] can however be used under an atmosphere of ethylene to effect a tandem ROM/CM to generate 57. The resulting triene can be induced to undergo Mo-catalyzed ARCM (5 mol % 4a) to afford optically pure 58, the AROM/RCM product that would be obtained from 55. 

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