LiCB11(CH3)12-Catalyzed Radical Polymerization of Isobutylene: Highly Branched Polyisobutylene and an Isobutylene−Ethyl Acrylate Copolymer

Volkis, Victoria; Mei, Hua; Shoemaker, Richard K.; Michl, Josef

doi:10.1021/ja807297g

Cited by 35 publications

(62 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Lithium salts are also used in conjunction with aprotic dipolar solvents for cellulose dissolution and as reaction media [6][7][8][9][10]. Further examples of condensed-phase applications can be found in the domain of catalysis by weakly coordinated lithium cation [11][12][13][14][15] and hydrogen storage [16][17][18][19][20]. Analytical mass spectrometry makes use of the formation of gas-phase adducts with metal cations (a process often called cationization), and Li + has been extensively examined in this regard.…”

Section: Introductionmentioning

confidence: 99%

Gas-Phase Lithium Cation Basicity: Revisiting the High Basicity Range by Experiment and Theory

Mayeux

Burk

Gal

et al. 2014

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

According to high level calculations, the upper part of the previously published FT-ICR lithium cation basicity (LiCB at 373 K) scale appeared to be biased by a systematic downward shift. The purpose of this work was to determine the source of this systematic difference. New experimental LiCB values at 373 K have been measured for 31 ligands by proton-transfer equilibrium techniques, ranging from tetrahydrofuran (137.2 kJ mol(-1)) to 1,2-dimethoxyethane (202.7 kJ mol(-1)). The relative basicities (ΔLiCB) were included in a single self-consistent ladder anchored to the absolute LiCB value of pyridine (146.7 kJ mol(-1)). This new LiCB scale exhibits a good agreement with theoretical values obtained at G2(MP2) level. By means of kinetic modeling, it was also shown that equilibrium measurements can be performed in spite of the formation of Li(+) bound dimers. The key feature for achieving accurate equilibrium measurements is the ion trapping time. The potential causes of discrepancies between the new data and previous experimental measurements were analyzed. It was concluded that the disagreement essentially finds its origin in the estimation of temperature and the calibration of Cook's kinetic method.

show abstract

Section: Introductionmentioning

confidence: 99%

Gas-Phase Lithium Cation Basicity: Revisiting the High Basicity Range by Experiment and Theory

Mayeux

Burk

Gal

et al. 2014

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

show abstract

mentioning

confidence: 71%

“…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.…”

mentioning

confidence: 79%

Radical Copolymerization of Isobutylene and Ethyl Acrylate with LiCB₁₁Me₁₂ Catalyst

et al. 2011

Self Cite

View full text Add to dashboard Cite

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...

show abstract

“…11 A practically important application of LiCB 11 Me 12 is catalysis of the radical polymerization of alkenes also reported by Michl. 12 In previous work 13 we demonstrated that chiral anionic complexes of potassium and silver K-or D-bis[N-salicylidene-(S)-aminoacidato]cobaltates 14 can be used as Lewis acid catalysts in asymmetric trimethylsilylcyanation of aldehydes and Mukayama aldol reaction. It was deemed interesting to extend this approach to examine C-C bond-forming reactions catalyzed by lithium Kor D-bis[N-salicylidene-(S)-aminoacidato]cobaltates.…”

Section: Introductionmentioning

confidence: 99%

Chiral ion pairs in catalysis: lithium salts of chiral metallocomplex anions as catalysts for asymmetric C–C bond formation

Belokoń

Maleev

Kataev

et al. 2009

Tetrahedron: Asymmetry

View full text Add to dashboard Cite

LiCB₁₁(CH₃)₁₂-Catalyzed Radical Polymerization of Isobutylene: Highly Branched Polyisobutylene and an Isobutylene−Ethyl Acrylate Copolymer

Cited by 35 publications

References 12 publications

Gas-Phase Lithium Cation Basicity: Revisiting the High Basicity Range by Experiment and Theory

Gas-Phase Lithium Cation Basicity: Revisiting the High Basicity Range by Experiment and Theory

Radical Copolymerization of Isobutylene and Ethyl Acrylate with LiCB₁₁Me₁₂ Catalyst

Chiral ion pairs in catalysis: lithium salts of chiral metallocomplex anions as catalysts for asymmetric C–C bond formation

Contact Info

Product

Resources

About

LiCB11(CH3)12-Catalyzed Radical Polymerization of Isobutylene: Highly Branched Polyisobutylene and an Isobutylene−Ethyl Acrylate Copolymer

Cited by 35 publications

References 12 publications

Gas-Phase Lithium Cation Basicity: Revisiting the High Basicity Range by Experiment and Theory

Gas-Phase Lithium Cation Basicity: Revisiting the High Basicity Range by Experiment and Theory

Radical Copolymerization of Isobutylene and Ethyl Acrylate with LiCB11Me12 Catalyst

Chiral ion pairs in catalysis: lithium salts of chiral metallocomplex anions as catalysts for asymmetric C–C bond formation

Contact Info

Product

Resources

About

LiCB₁₁(CH₃)₁₂-Catalyzed Radical Polymerization of Isobutylene: Highly Branched Polyisobutylene and an Isobutylene−Ethyl Acrylate Copolymer

Radical Copolymerization of Isobutylene and Ethyl Acrylate with LiCB₁₁Me₁₂ Catalyst