Heptadienes cyclopolymerization

Cyclopolymerization of Nonconjugated Dienes. Cyclopolymerization is an addition polymerization that leads to introduction of cyclic structures into the main chain of the polymer. Nonconjugated dienes are the most deeply studied monomers for cyclopolymerization and for cyclocopolymerizations with alkene monomers 66 In general, (substituted and unsubstituted) dienes with double bonds that are linked by less than two or more than four atoms cannot undergo efficient cyclization and result in crosslinked materials.12 In fact, efficient cyclopolymerization processes have been described, for instance, for a,oo-dienes like 1,5-hexadiene, 2-methyl-l,5-hexadiene, 1,6-heptadiene, and 1,7-octadiene,67 73 which lead to formation of homopolymers and copolymers containing methylene-1,3-cycloalkane units. 

Cyclopolymerizations of functionalized 1,6 dienes such as 4-trimethyl-silyoxy-1,6-heptadiene are also possible, with B(C6F5)3 as cocatalyst and bis-(pentamethylcyclopentadienyl)zirconocenes as catalysts. Hydrolysis of the product with HC1 gives polymethylene-3-hydroxycyclohexane. With the same catalyst, Kesti et al. (269) succeeded in polymerizing 5-/ /V-diisoprop-lyl-amino-l-pentene and 4-tert-butyldimethylsiloxy-l-pentene. 

Polymerization of a-tv-diolefins has also been investigated to further explore the unusual regiochemistry exhibited by bis(phenoxy-imine) Ti catalysts. Cyclopolymerization of 1,6-heptadiene (see Figure 55) produced a polymer with no observable unsaturations. This indicated quantitative cyclization of the monomer. The NMR analysis of the polymer indicated the presence of ethylene-1,2-cyclopentane units and of methylene-1,3-cyclohexane units in almost... 

Figure 55 Cyclopolymerization of 1,6-heptadiene with bis(phenoxy-imine) Ti based catalysts.

Scheme 5.11 Cyclopolymerization of heptadienes. X=C(COOEt)2, C((1S, IR, 5S)-(+)-menthyloxy-carbonyl), C(COOEt) ((1 S.2R.5S)-(+)-menthyloxycarbonyl).

FIGURE 19.1 Maximum order structures of the cyclopolymers produced by the cyclopolymerization of 1,5-HD (a), 1,6-heptadiene (b), and 1,7-OD (c) with metallocene catalysts. These structures are also referred to as cis-diisotactic (me o-diisotactic), cis-disyndiotactic (m 56>-disyndiotactic), trans-diisotactic (racemo-diisotactic), and trans-disyndiotactic (rac mo-disyndiotactic). 

Method 5. Other Methods of Initiation Catalysts were prepared by the interaction of molybdenum or tungsten hexacarbonyl with bicyclo(2.2.1]heptadiene or cycloheptatriene (Si). They were described as being effective for the cyclopolymerization of [9] and [143]. 

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