Reference : Anionic polymerization of acrylic monomers. 11 NMR investigation of the mixed complexati...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Chemistry
Engineering, computing & technology : Materials science & engineering
http://hdl.handle.net/2268/16019
Anionic polymerization of acrylic monomers. 11 NMR investigation of the mixed complexation of methyl α-lithioisobutyrate and lithium chloride
English
Wang, Jin-Shan [University of Liège (ULg) > Department of Chemistry > Center for Education and Research on Macromolecules (CERM) > >]
Warin, R. [University of Liège (ULg) > Department of Chemistry > Center for Education and Research on Macromolecules (CERM) > >]
Jérôme, Robert mailto [University of Liège (ULg) > Department of Chemistry > Center for Education and Research on Macromolecules (CERM) > >]
Teyssié, Philippe [University of Liège (ULg) > Department of Chemistry > Center for Education and Research on Macromolecules (CERM) > >]
6-Dec-1993
Macromolecules
American Chemical Society
26
6776-6781
Yes (verified by ORBi)
International
0024-9297
Washington
DC
[en] anionic polymerization ; (meth)acrylate
[en] Solutions of methyl α-lithioisobutyrate (MIBLi) in THF added with various amounts of lithium chloride (LiCl) have been analyzed by Li-7 NMR spectroscopy in a wide range of temperatures. Although below ca. 205 K tetramers of MIBLi have been reported to be in equilibrium with dimers, 1/1 and 2/1 LiCl/MIBLi mixed complexes instantaneously form upon the addition of 1 and 2 mol equiv of LiCl, respectively. Further addition of LiCl more likely promotes the formation of a less stable 3/1 complex. Both 1/1 and 2/1 adducts are stable between -80-degrees-C and at least +12-degrees-C. From C-13 NMR spectroscopy, it appears that the addition of an equimolar amount of LiCl to the MIBLi solution in THF is at the origin of a ca. 7.0 ppm upfield shift of the metalated α-carbon compared to the tetrameric MIBLi species and a ca. 1.0 ppm downfield shift with respect to the dimeric MIBLi. However, the charge distribution over the carbanion does not change anymore when the amount of LiCl exceeds 1 mol equiv. In contrast to nonligated MEBLi, the OR group has a considerable rotational freedom in LiCl-modified MIBLi. A comparison of the structure and dynamics of the LiCl-modified MIBLi species in THF at 197 K with the characteristic features of the anionic polymerization of MMA under the same conditions suggests that the formation of one type of LiCl-complexed species has a decisive effect on the control of the living polymerization of MMA. This conclusion is in agreement with a kinetic study carried out by Muller for the same system.
Center for Education and Research on Macromolecules (CERM)
Politique Scientifique Fédérale (Belgique) = Belgian Federal Science Policy ; Elf Atochem
Researchers
http://hdl.handle.net/2268/16019
10.1021/ma00077a013
http://pubs.acs.org/doi/pdf/10.1021/ma00077a013

File(s) associated to this reference

Fulltext file(s):

FileCommentaryVersionSizeAccess
Restricted access
Wang JS 1993 Macromolecules 6776.pdfPublisher postprint704.76 kBRequest copy

Bookmark and Share SFX Query

All documents in ORBi are protected by a user license.