Polymer reaction 1,4-poly-1,3-diene

The deliberate introduction of multifunctional branching into anionically prepared polydiene and poly (diene-co-styrene) polymers produces materials with unique morphological and viscoelastic properties (1-3). Work has included synthesis of symmetric star polymers produced by reaction of living polyanionic "arms" with multi-functional chlorosilane (4-9),... 

The tetrahydrofuran heterocycle has been incorporated into the main chain of a polymer by a ring expansion reaction of an epoxidized poly(diene) (172) (79BRP1550017). The reaction apparently takes place with equal efficiency (Scheme 85) with either nucleophilic or electrophilic initiation. 

One of the time honored polymer modification reactions resulting in heterocyclic polymer formation is reaction of a poly(diene) with maleic anhydride or a maleimide (B-64MI11100). Two modification techniques have, in general, been employed—one catalyzed or initiated, the other not. Although most reports deal with modifications using maleic anhydride, A-alkylmaleimides are reported to behave in a completely analogous fashion. 

The reader should note that stereoisomerism does not exist if the substituents X and Y in the monomer 4-14 are identical. Thus there are no configurational isomers of polyethylene, polyisobutene, or polyfvinylidene chloride). It should also be clear that 1,2-poly-butadiene (reaction 4-3) and the 1,2- and 3,4-isomers of polyisoprene can exist as isotactic, syndiotactic. and atactic configurational isomers. The number of possible structures of polymers of conjugated dienes can be seen to be quite large when the possibility of head-to-head and head-to-tail isomerism is also taken into account. 

Free-radical polymerization reactions have recently been studied for different monomers, for example mono and disubstituted vinyl monomers and dienes. The bulk polymerization of vinyl monomers (e.g. vinyl acetate, styrene, methyl methacrylate, and acrylonitrile) has been investigated by Amorim et al. [10]. The reactions were conducted in the presence of catalytic amounts of AIBN (or benzoyl peroxide). It was found that the rate of polymerization depends on the structure of the monomers and the power and time of microwave irradiation. In a typical experiment 10.0 mL of each monomer and 50 mg AIBN was irradiated in a domestic microwave oven for 1 to 20 min to afford the polymers polystyrene, poly(vinyl acetate), and poly(methyl methacrylate) with weight-average molecular weights 48 400, 150 200, 176700 g mol, respectively (Scheme 14.1). The experiments were performed without temperature control. 

The thermal reaction of cis or trans 1,4-poly(butadiene) with iron carbonyls results in geometrical isomerization of the alkenyl moieties and formation of polymers containing conjugated diene) iron tricarbonyl units. In the course of our continuing studies of the formation of stable colloidal iron dispersions by thermal decomposition of metal carbonyls in the presence of functional polymers, some aspects of this work have been repeated. Our objective was to isolate the soluble organometallic polymer which was intermediate to particle nucleation and independently examine the intramolecular condensation of metal atoms to yield metal clusters and metal particles. In this paper, the structure of the intermediate obtained on thermolysis of an excess of FeCCO) in a dilute xylene solution of c/5-poly(butadiene) has been described. 

C/5-2,6 octadiene would be the most appropriate small molecular model for the repeat unit in m-poly(butadiene). However, in light of the fact that FeCCO) catalyzes double bond migration and isomerization any isomeric octadiene monomer should serve as an appropriate model for the polymer reaction. We reacted 1,7-octadiene with FeCCO) and obtained a simple infrared spectrum which was nearly identical to that for the reaction product of c/5-poly (butadiene) with Fe(C0)5, i.e., both materials displayed two discrete peaks in the carbonyl region, a sharp peak at 2050 cm and a broad absorption ( "30 cm HWHH) centered at 198O cm" (See Fig. 2). The broad unresolved character of the 1980 cm" band, as compared to that in rj -butadiene iron tricarbonyl which shows discrete sharp peaks at 1980 and 1990 cm in addition to the sharp peak at 2056 cm", can be understood in terms of the variety of isomeric diene iron tricarbonyls which can be formed in the reaction of FeCCO) with either c/5-poly(butadiene) or 1,7-octadiene. 

The NMR spectroscopy results show that the maleic anhydride addition is carried out as an ene-reaction [59-61] by the vinyl bonds of the polymer without the cycle disclosure and the double bond is moved to the p-carbon atom of the vinyl bond [55,57], The maleic anhydride addition to the >C=C< double bonds of 1,4-units of poly diene macromolecules does not take place. As in synthesis of the arylamino derivatives of syndiotactic 1,2-PB, it is connected with steric difficulties preventing the interaction of bulk molecules of the maleic anhydride with iimer double bonds of the polymer chain [56]. 

The polymers prepared from thexylborane and diene monomers were reacted with carbon monoxide at 120°C, followed by treatment with NaOH and H202 to produce a polyalcohol (scheme 5).13 This conversion includes migration of the polymer chain and thexyl group from the boron atom to carbon, as shown in scheme 5. When this reaction was carried out under milder condition, poly(ketone) segments were included in the polymer backbone due to an incomplete migration of the thexyl group. 

It is evident that reactions of unsaturated polymers with bisnitrile oxides lead to cross-linking. Such a procedure has been patented for curing poly(butadiene), butadiene-styrene copolymer, as well as some unsaturated polyethers and polyesters (512-514). Bisnitrile oxides are usually generated in the presence of unsaturated polymers by dehydrochlorination of hydroximoyl chlorides. Cross-linking of ethylene-propylene-diene co-polymers with stable bisnitrile oxides has been studied (515, 516). The rate of the process has been shown to reduce in record with the sequence 2-chloroterephthalonitrile oxide > terephthalonitrile oxide > 2,5-dimethylterephthalonitrile oxide > 2,3,5,6-tetramethylterephthalo-nitrile oxide > anthracene-9,10-dicarbonitrile oxide (515). 

Asymmetric Diels-Alder reactions have also been achieved in the presence of poly(ethylene glycol)-supported chiral imidazohdin-4-one [113] and copper-loaded silica-grafted bis(oxazolines) [114]. Polymer-bound, camphor-based polysiloxane-fixed metal 1,3-diketonates (chirasil-metals) (37) have proven to catalyze the hetero Diels-Alder reaction of benzaldehyde and Danishefsky s diene. Best catalysts were obtained when oxovanadium(lV) and europium(III) where employed as coordinating metals. Despite excellent chemical yields the resulting pyran-4-ones were reported to be formed with only moderate stereoselectivity (Scheme 4.22). The polymeric catalysts are soluble in hexane and could be precipitated by addition of methanol. Interestingly, the polymeric oxovanadium(III)-catalysts invoke opposite enantioselectivities compared with their monomeric counterparts [115]. 

Side chain furan functionalization has been accomplished by acetalization (Section 1.11.4.4.3) of poly(vinyl alcohol) (180) with furan-3-carbaldehyde (181 Scheme 87) (72MI11106). The adduct (182) was utilized as the diene reactant in a Diels-Alder reaction to bind vinyl-functional siloxane oligomers to the polymer. 

The formation of polymers containing [=CH(CH2)4CH=], units is possible through the ROMP of an appropriate cyclic diene, such as cycloocta-1,3-diene, or by a double-bond shift reaction of a polymer such as poly(l-pentenylene). Such units can be eliminated as cyclohexene so long as metathesis activity is present in the system360. The ROMP of 2,3-dihydropyran, initiated by Mo(CO)6/CBr4// v, has been reported361. 

---