Towards the control of the reactivity in high temperature anionic polymerization of styrene: retarded anionic polymerization. 3– influence of triisobutylaluminum on the reactivity of polystyryllithium species

Desbois, Philippe; Fontanille, Michel; Deffieux, Alain; Warzelhan, Volker; Schade, Christian

doi:10.1002/1521-3900(200007)157:1<151::aid-masy151>3.0.co;2-9

Cited by 17 publications

(23 citation statements)

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“…In light of these results and previously reported reactivity data, [13] the 1:1 i Bu 3 Al/PBLi heterocomplex is assumed to be inactive (no polymerization observed at r ! 1).…”

Section: Styrene/butadiene Copolymerization Reactivity Ratiossupporting

confidence: 55%

“…At an equimolar [Al]/[Li] ratio (r ¼ 1), the initial band has totally disappeared, in agreement with the quantitative formation of a 1:1 i Bu 3 Al/PBLi complex as already reported for i Bu 3 Al/PSLi. [13][14][15][16] No further modification of the UV-visible spectrum was noticed when adding a higher amount of i Bu 3 Al to this system.…”

Section: Uv-visible Investigation Of Active Speciesmentioning

confidence: 99%

“…[10][11][12][13] Much less data are available concerning diene polymerization. The kinetics of buta-1,3-diene polymerization initiated by PBLi seeds in the presence of the Lewis acid additives were investigated in cyclohexane at 40 8C using the dilatometry technique.…”

Section: Buta-13-diene Polymerizationmentioning

confidence: 99%

“…No butadiene polymerization is observed for r equal or higher than one, as already described for styrene. [13] Experimental PB molar masses can be compared to theoretical ones assuming one PB chain formed by initial PBLi seeds. Data are in agreement with an initiation involving all the initial PBLi species, independently of r, and the non-participation of the aluminium derivative.…”

Section: Buta-13-diene Polymerizationmentioning

confidence: 99%

“…More recently, we have investigated in greater detail and over a much broader range the use of R 2 Mg (0 < [Mg]/[Li] ¼ 20) and of trialkylaluminium (R 3 Al) (0 < [Al]/[Li] < 1) as retarders of the styrene anionic polymerization initiated by alkyllithium derivatives at elevated temperature. [10][11][12][13] The formation of ''ate'' heterocomplexes between PSLi and the organometallic additives was found as the keystone for the retardation effect and the stabilization of active species at high temperature. However, the exact nature of the propagating species was not completely elucidated.…”

Section: Introductionmentioning

confidence: 99%

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Retarded Anionic Polymerization: Copolymerization of Butadiene and Styrene in the Presence of Alkyllithium and n,s‐Dibutylmagnesium or Triisobutylaluminium Derivatives

Carlotti

Ménoret

Barabanova

et al. 2004

Macro Chemistry & Physics

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Summary: The influence of Lewis acid additives on the anionic butadiene polymerization using lithium as a counter ion in non‐polar solvent is investigated. A decrease of the polymerization rate was always observed. In the presence of n,s‐Bu2Mg the percentage of 1,2‐vinyl units increases with the [Mg]/[Li] ratio. This evolution can be explained by further complexation of lithium with free dialkylmagnesium modifying the nature of the propagating species and/or possible 1,4 to 1,2 isomerization during chain exchanges between lithium and magnesium derivatives. As a result of the transmetallation process, 0.5 to 1 supplementary chains are formed by magnesium depending on the [Mg]/[Li] ratio. In contrast, the iBu3Al/RLi system does not yield any modification of polybutadiene microstructure, which remains close to the one observed with s‐BuLi alone. The determination of the reactivity ratios in styrene‐butadiene copolymerization shows that tapered‐like copolymers are obtained in the presence of both n,s‐Bu2Mg and iBu3Al. However the magnesium derivative induces a lesser increase of styrene incorporation in the copolymer than the aluminium additive. The observed microstructure and reactivity ratios support that the monomer insertion proceeds directly into heterocomplexes.magnified image

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“…In light of these results and previously reported reactivity data, [13] the 1:1 i Bu 3 Al/PBLi heterocomplex is assumed to be inactive (no polymerization observed at r ! 1).…”

Section: Styrene/butadiene Copolymerization Reactivity Ratiossupporting

confidence: 55%

Section: Uv-visible Investigation Of Active Speciesmentioning

confidence: 99%

Section: Buta-13-diene Polymerizationmentioning

confidence: 99%

Section: Buta-13-diene Polymerizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Retarded Anionic Polymerization: Copolymerization of Butadiene and Styrene in the Presence of Alkyllithium and n,s‐Dibutylmagnesium or Triisobutylaluminium Derivatives

Carlotti

Ménoret

Barabanova

et al. 2004

Macro Chemistry & Physics

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Synthesis of Epothilone Analogues by Antibody-Catalyzed Resolution of Thiazole Aldol Synthons on a Multigram Scale. Biological Consequences of C-13 Alkylation of Epothilones

et al. 2001

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Three monoclonal aldolase antibodies (84G3, 85H6, and 93F3), generated against a beta-diketone hapten (II) by the reactive immunization technique, catalyzed highly enantioselective retro-aldol reactions of the racemic thiazole aldols 13-20. Antibody 84G3 (0.0004-0.005 mol%) was used to resolve (+/-)-13-(+/-)-18 to afford compounds 13-18 in multigram quantities. Multiple 13-alkyl analogues of epothilone (7-12) and their trans isomers ((E)-7-(E)-12) were synthesized starting from thiazole aldols 13-18. Construction of the trisubstituted olefin moiety in compounds 7-12 and (E)-7-(E)-12 was catalyzed by Grubbs' catalyst (X). Initial biological testing with compounds 7-10 and their trans isomers showed that compounds 9, 10, and (E)-10 have appreciable tubulin polymerization and antiproliferative activities that approached those of epothilone C. The most active compound, (E)-9, even displayed potencies comparable to those observed for epothilones A and D. Interestingly, all trans analogues were more potent than their corresponding cis isomers. While introduction of an alkyl group at C-13 in the cis series led to an overall reduction in biological activity (compared to epothilone C), appropriate modification of the thiazole moiety (replacement of the 2-methyl substituent by a 2-methylthio group) was able to compensate for this loss. These results are encouraging in view of the expectation that epoxidations of these compounds should further increase their cellular activities. Thus, compounds 9, 10, and (E)-9 and (E)-10 represent highly promising candidates for further studies.

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Anionic Polymerization of Vinyl and Related Monomers

Fontanille

Gnanou

2007

Macromolecular Engineering

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Towards the control of the reactivity in high temperature anionic polymerization of styrene: retarded anionic polymerization. 3– influence of triisobutylaluminum on the reactivity of polystyryllithium species

Cited by 17 publications

References 0 publications

Retarded Anionic Polymerization: Copolymerization of Butadiene and Styrene in the Presence of Alkyllithium and n,s‐Dibutylmagnesium or Triisobutylaluminium Derivatives

Retarded Anionic Polymerization: Copolymerization of Butadiene and Styrene in the Presence of Alkyllithium and n,s‐Dibutylmagnesium or Triisobutylaluminium Derivatives

Synthesis of Epothilone Analogues by Antibody-Catalyzed Resolution of Thiazole Aldol Synthons on a Multigram Scale. Biological Consequences of C-13 Alkylation of Epothilones

Anionic Polymerization of Vinyl and Related Monomers

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