Pd‐Catalyzed Polymerization of Dienes that Involves Chain‐Walking Isomerization of the Growing Polymer End: Synthesis of Polymers Composed of Polymethylene and Five‐Membered‐Ring Units

2012

Polym J

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Pd complexes with diimine ligands promoted the controlled cyclopolymerization of 1,6-dienes and 1,6,11-trienes to afford polymers containing 1,2-trans-cyclopentane groups with well-regulated stereochemistry. The polymerization proceeded with quantitative cyclization of the monomer, even under bulk conditions or in copolymerization reactions with ethylene and aolefins. The polymerization of monomers with oligomethylene spacers yielded polymers with five-membered rings that are accurately distributed along the polymer chain. 4-Alkylcyclopentenes and alkenylcyclohexanes were also polymerized by Pddiimine complexes to afford polymers with 1,3-trans-cyclopentane groups and 1,4-trans-cyclohexane groups, respectively. Pd complexes with a C 2 symmetrical structure promoted the isospecific polymerization of 4-alkylcyclopentenes, and the resultant isotactic polymers showed liquid crystalline properties. The mechanism of the polymerization reaction has been revealed.

Section: Isomerization Cyclopolymerization Of Monoalkyl-substituted Dmentioning

confidence: 98%

Stereo-controlled synthesis of polyolefins with cycloalkane groups by using late transition metals

2012

Polym J

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“…Re-addition of the monomer after the polymerization (M n = 10 800 and M w /M n = 1.10) at À10 8C causes the resumption of polymer growth to yield a product with M n = 18 500 and M w /M n = 1.24 (conversion = 93 %), which indicates living cyclopolymerization at that temperature. Cyclopolymerization of the monomers with cyclic imide groups (III-V) affords the corresponding five-membered ring polymers (Table 1, entries [11][12][13]. Diethyl diallylmalonate (VI), without a cyclic group in the monomer, also undergoes the cyclopolymerization catalyzed by 1 b/NaBARF to produce poly-VI, at a lower rate than the polymerization of I (Table 1, entry 14 versus 2).…”

Section: Resultsmentioning

confidence: 98%

“…The resonance is at a higher magnetic field than that of poly-I (d = 47.0 ppm) and is similar to the polymer of isopropylidene allylA C H T U N G T R E N N U N G (2-pentyl)malonate (shown here), which has an alternating sequence of the cyclized diene unit and a ÀA C H T U N G T R E N N U N G (CH 2 )À group (d = 46.4 ppm). [11] Diene II, which has a cyclic diketone group, also forms a copolymer, which contains 21 % of the repeating units from II (Table 2, entry 2). Dienes III-VII, IX, and X, containing a polar group, also copolymerize with ethylene to give the respective copolymers (Table 2, entries 3-9).…”

Section: A-iv)mentioning

confidence: 99%

“…Cyclopolymerization of monoterminal 1,6-dienes affords polymers with 1,2-trans-fused five-membered rings linked by polymethylene spacers. [11] These reactions contrast with the cyclopolymerization of 1,6-heptadienes catalyzed by complexes of early transition metals, [12] which form polymers with irregular structures or primarily contain sixmembered rings, except for the reactions discussed in recent reports by Coates and co-workers. [13,14] Complexes of other late-transition metals, such as Co and Fe, catalyze cyclopolymerization to form polymers with trans-and/or cis-fused five-membered rings.…”

Section: Introductionmentioning

confidence: 98%

See 1 more Smart Citation

Cyclopolymerization and Copolymerization of Functionalized 1,6‐Heptadienes Catalyzed by Pd Complexes: Mechanism and Application to Physical‐Gel Formation

Park

Okada

et al. 2010

Chemistry A European J

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Cationic Pd complexes, prepared from [PdCl(ArN=C(12)H(6)=NAr)(Me)] and Na[B{3,5(CF(3))(2)C(6)H(3)}(4)] (NaBARF), catalyze the cyclopolymerization of 4,4-disubstituted 1,6-heptadienes. The polymers produced contain a trans-fused five-membered ring in each repeating unit. NMR spectroscopy and FAB mass spectrometry of the polymers formed indicated that the initiation end of the chain contains either the cyclopentyl group derived from the preformed Pd-monomer complex or a hydrogen atom left on the Pd center by the chain-transfer reaction. The stable cyclopentylpalladium species are involved in both initiation and propagation steps and undergo isomerization into (cyclopentylmethyl)palladium species followed by the insertion of a CH=CH(2) bond of a new monomer molecule into the Pd-CH(2) bond. Copolymerization of 1,6-heptadiene derivatives with ethylene, catalyzed by the Pd complexes, yields polymers that contain trans five-membered rings and branched oligoethylene units. Copolymerization of isopropylidene diallylmalonate with 1-hexene affords a polymer with 26% diene incorporation. The copolymerization consumes 1-hexene more readily than isopropylidene diallylmalonate, although gel permeation chromatography and NMR spectroscopy of the polymers produced show the formation of copolymers rather than of a mixture of homopolymers. Polymerization of 1-hexene initiated with a Pd-barbiturate complex and terminated with 5-allyl-5-hexylpyrimidine-2,4,6(1H,3H,5H)-trione/Et(3)SiH leads to polyhexene with barbiturate moieties at both terminal ends. Addition of 5-hexyl-2,4,6-triaminopyrimidine to a toluene solution of the telechelic poly(1-hexene) converts the solution into gel.

“…Pd-catalyzed polymerization of 1,6-heptadiene having alkyl group on 7-position is accompanied by chain walking reaction to give the polymer containing both cyclopentane and oligomethylene groups in alternating sequence [256]. The intervals between neighboring cyclopentane groups can be controlled by the length of alkyl group of the monomer.…”

Section: Cyclopolymerization Of Non-conjugated Dienesmentioning

confidence: 99%

Olefin Polymerization with Non-metallocene Catalysts (Late Transition Metals)

Organometallic Reactions and Polymerization

2014

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Diimine Pd and Ni complexes catalyze the polymerization of ethylene, propylene, and a-olefins. The reaction involves isomerization of the growing terminal (chain walking) and, as its result, produces highly branched polyethylene and poy(a-olefin)s having a smaller number of the alkyl substituents than expected from the monomer structure. Ni complexes with salicylaldimine or iminocarboxamide ligands and Pd complexes with phosphinesulfonate ligands are used as single component catalysts for ethylene polymerization. Especially, the latter catalysts show tolerance towards polar functional groups and promote copolymerization of ethylene with wide varieties of polar monomers. The Pd and Ni complexes are able to catalyze ethylene polymerization in aqueous media to yield polyethylene particles. Fe and Co complexes with bis(imino)pyridine ligands show high catalytic activity for ethylene polymerization to yield linear polyethylene. Complexes of the metals such as Rh, Ir, Ru, and Ag were revealed to become catalytically active by proper design of the ligand. Not only monometallic complexes but also bimetallic or multimetallic complexes are used for ethylene polymerization. Late transition metal complexes catalyze selective cyclopolymerization of non-conjugated dienes and trienes to afford the polymers with cycloalkane groups with controlled stereochemistry.