Peroxide Oxidation of Arabinogalactan: Kinetics and Products

Monakov, Yu. B.; Борисов, И. М.; Zimin, Yu. S.; Mudarisova, R. Kh.; Широкова, Е. Н.; Толстикова, Т. Г.; Медведева, С. А.; Заиков, Г. Е.

doi:10.1002/chin.200630272

Cited by 3 publications

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“…The polymerization is performed at very low temperatures to avoid transfer reactions and achieve the high molar mass that is needed for PIB to be rubbery. Butyl rubber (IIR), a copolymer of IB and isoprene, is also manufactured at low temperature. , …”

Section: Introduction: Polymerization Of Alkenesmentioning

confidence: 99%

Li⁺Catalysis and Other New Methodologies for the Radical Polymerization of Less Activated Olefins

et al. 2016

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Section: Introduction: Polymerization Of Alkenesmentioning

confidence: 99%

Li⁺Catalysis and Other New Methodologies for the Radical Polymerization of Less Activated Olefins

et al. 2016

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“…Haloalkanes or aromatic hydrocarbons are usually used as reaction medium. Butyl rubber, i.e., a copolymer of IB and isoprene, is manufactured at low temperature in liquid ethylene …”

Section: Introductionmentioning

confidence: 99%

Highly Branched Polyisobutylene by Radical Polymerization under Li[CB₁₁(CH₃)₁₂] Catalysis

2012

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In the presence of a nonoxidizing radical initiator, azo-tert-butane, and a high concentration of LiCB11(CH3)12, isobutylene undergoes thermal or light-induced radical polymerization to b-PIB, a highly branched polymer of modest molecular weight (mostly a few thousand and up to ∼25 000 g/mol based on GPC with polystyrene standards). The structure of b-PIB was elucidated by NMR spectroscopy of a low-molecular-weight fraction. The polymer is branched on every carbon atom of the main chain; one chain end carries an isobutenyl group, and the other carries a tert-butyl group originating in the initiator. The branches are short segments of l-PIB (linear polyisobutylene), on the average composed of five IB units. A mechanism of formation if this dendrimer-like structure is proposed.

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“…EA and IB can be copolymerized, but it is difficult due to different reactivity . IB is normally polymerized cationically to a linear polymer with AlCl 3 in halogenated hydrocarbons in the presence of traces of water . In contrast, ethyl acrylate is ordinarily polymerized under radical initiation, sometimes under catalysis with rare earth metal complexes or other metal-containing species. − …”

Section: Introductionmentioning

confidence: 99%

Radical Copolymerization of Isobutylene and Ethyl Acrylate with LiCB₁₁Me₁₂ Catalyst

et al. 2011

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The radical homopolymerization of isobutylene (IB) is unusual but can be accomplished under catalysis with LiCB 11 (CH 3 ) 12 (1) in poorly coordinating solvents at ambient pressure and temperature. 1-3 It yields a novel highly branched form of polyisobutylene (b-PIB) with molecular weights in the thousands (up to ∼2.5 Â 10 4 ) according to GPC relative to polystyrene standards. Presently we examine the use of the LiCB 11 (CH 3 ) 12 catalyst with azo-tertbutane (ATB) radical initiator for the copolymerization of IB with ethyl acrylate (EA), as previously briefly mentioned in a short communication. 2 We find that it leads to an unusual somewhat branched nonalternating high molecular weight copolymer with up to ∼56 mol % of IB.EA and IB can be copolymerized, but it is difficult due to different reactivity. 4 IB is normally polymerized cationically to a linear polymer with AlCl 3 in halogenated hydrocarbons in the presence of traces of water. 5 In contrast, ethyl acrylate is ordinarily polymerized under radical initiation, sometimes under catalysis with rare earth metal complexes 6 or other metal-containing species. [7][8][9][10] The poor copolymerization potential of IB with acrylic esters in a radical process is apparent from the monomer reactivity ratio. The Alfrey-Price Q-e value 11 reactivity ratio of IB is more than 10 times lower than that of EA. 12 Still, conventional radical copolymerization of the two monomers results in a poly(ethyl acrylate) (PEA) containing a fair number of IB units. 13,14 For example, thermal or UV peroxide initiated radical copolymerization of IB and EA provides a low molecular weight product containing 20-30 mol % of IB. 14 The situation is improved by addition of strong Lewis acids, such as AlR n Cl 3-n , 15-17 BF 3 , 18 SnCl 4 , 18 ZnCl 2 , 18 etc. A high molecular weight alternating copolymer containing 50 mol % of IB was obtained using alkylaluminum and alkylboron halides as catalysts. 19 Metal-catalyzed coordination polymerizations are highly effective for olefins, but less so for polar acrylic monomers. Although recently, functionality tolerant late transition metal catalysts were used to catalyze the copolymerization, 20,21 EA/IB copolymers are still produced commercially by free-radical polymerization because other methods are too costly. 22' EXPERIMENTAL SECTION Materials. IB (Airgas) was pure grade (>99%) and was dried over activated 3 Å molecular sieves. EA (Aldrich) was distilled, dried over 4 Å molecular sieves, and stored in a Schlenk tube. 1,2-Dichloroethane (DCE, Aldrich) was dried with P 2 O 5 and distilled twice before use. ATB (Aldrich) was ∼97% pure. EA-d 5 and IB-d 8 were ordered from CDN Isotopes Inc. LiCB 11 Me 12 23 was dried under reduced pressure (∼0.04 mbar) at 100°C overnight before use. It contained residual sulfolane in a molar ratio sulfolane:LiCB 11 Me 12 = ∼1:10.Polymerization. Polymerization was conducted in a 25 mL stainless steel pressure reactor with a Teflon insert, a stir bar, and an accurate pressure gauge. In a typical reaction, the dried cata...

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Peroxide Oxidation of Arabinogalactan: Kinetics and Products

Cited by 3 publications

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Li⁺Catalysis and Other New Methodologies for the Radical Polymerization of Less Activated Olefins

Li⁺Catalysis and Other New Methodologies for the Radical Polymerization of Less Activated Olefins

Highly Branched Polyisobutylene by Radical Polymerization under Li[CB₁₁(CH₃)₁₂] Catalysis

Radical Copolymerization of Isobutylene and Ethyl Acrylate with LiCB₁₁Me₁₂ Catalyst

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Peroxide Oxidation of Arabinogalactan: Kinetics and Products

Cited by 3 publications

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Li+Catalysis and Other New Methodologies for the Radical Polymerization of Less Activated Olefins

Li+Catalysis and Other New Methodologies for the Radical Polymerization of Less Activated Olefins

Highly Branched Polyisobutylene by Radical Polymerization under Li[CB11(CH3)12] Catalysis

Radical Copolymerization of Isobutylene and Ethyl Acrylate with LiCB11Me12 Catalyst

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Li⁺Catalysis and Other New Methodologies for the Radical Polymerization of Less Activated Olefins

Li⁺Catalysis and Other New Methodologies for the Radical Polymerization of Less Activated Olefins

Highly Branched Polyisobutylene by Radical Polymerization under Li[CB₁₁(CH₃)₁₂] Catalysis

Radical Copolymerization of Isobutylene and Ethyl Acrylate with LiCB₁₁Me₁₂ Catalyst