822-90-2Relevant articles and documents
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Weidenhagen,Herrmann
, p. 1986 (1935)
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Weidenhagen,Rienaecker
, p. 57,63,64 (1939)
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Lewis Pair Polymerization of Epoxides via Zwitterionic Species as a Route to High-Molar-Mass Polyethers
Walther, Patrick,Krau?, Annabelle,Naumann, Stefan
supporting information, p. 10737 - 10741 (2019/07/04)
A dual catalytic setup based on N-heterocyclic olefins (NHOs) and magnesium bis(hexamethyldisilazide) (Mg(HMDS)2) was used to prepare poly(propylene oxide) with a molar mass (Mn) >500 000 g mol?1, in some cases even >106 g mol?1, as determined by GPC/light scattering. This is achieved by combining the rapid polymerization characteristics of a zwitterionic, Lewis pair type mechanism with the efficient epoxide activation by the MgII species. Transfer-to-monomer, traditionally frustrating attempts at synthesizing polyethers with a high degree of polymerization, is practically removed as a limiting factor by this approach. NMR and MALDI-ToF MS experiments reveal key aspects of the proposed mechanism, whereby the polymerization is initiated via nucleophilic attack by the NHO on the activated monomer, generating a zwitterionic species. This strategy can also be extended to other epoxides, including functionalized monomers.
Syntheses of polyalkylated imidazoles
Evjen, Sigvart,Fiksdahl, Anne
supporting information, p. 1392 - 1399 (2017/07/25)
We have developed improved general simple methods for large-scale preparation of polyalkylated imidazoles by improved multicomponent synthesis from commercially available starting materials. A large range of NH- and N-alkyl-polyalkylimidazoles (40 in total, including novel compounds) has been synthesized.