Imidazolium ring opening

Imidazolium halides pyrolysis, 5, 449 Imidazolium ions acylation, 5, 402 H NMR, 5, 352 hydrogen exchange, 5, 417 nucleophilic attack, 5, 375 reactivity, 5, 375 ring opening, S, 375 Imidazolium oxides in pyrrole synthesis, 4, 344 Imidazolium perchlorate, 1,3-diphenyl-acylation, 5, 402 Imidazolium salts 1-acetyl-... 

Table 1 Characterization of polymers obtained by ring-opening polymerization of PO catalyzed by DMC catalpts in the presence of QASs and imidazolium salts...

This facile solution for catalyst immobilisation follows a more complex approach reported by Mayr et al. [246], This research group attached the imidazolium salt to a nor-bomene unit that was then subjected to a ring opening metathesis polymerisation (ROMP) reaction to form the polymeric NHC precursor (see Figure 4.77). The ROMP reaction had to be carried out with a molybdenum based Schrock catalyst because the ruthenium based Grubbs catalyst did not provide an endgroup that could be quantitatively capped with a suitable final endgroup. 

Various azole ylides react with alkynes or alkenes with subsequent ring opening and recyclization. Thus pyrazolium ylide (348) gives compound (349) (Equation (188)) <93JCS(P1)883>, imidazolium ylide (350) gives (351) (Equation (189)) <91H(32)2217>, and thiazolium ylide (352) gives (353) (Equation (190)) <76JOC187>. 

A similar class of siloxane polymers was created with imi-dazolium groups (Cl5). ° Monomer synthesis consisted of combining N-allylimidazole and methyldiethoxysilane at elevated temperature. Homopolymers were created by polycondensation. Polymers with dimethylsiloxane spacers were also created by anionic ring-opening polymerization. Both classes of imidazole polymers were then reacted with n-octyl bromide to create the imidazolium side chains. Bactericidal activities of these polymers were similar to the quaternary ammonium polymers. 

An ionic liquid also has vast possibilities because the hquid properties as a solvent can be altered by designing the molecular structure. There are a few reports of enzymatic ring-opening polymerization in ionic liquids. The hpase-catalyzed polymerization of e-CL was carried out in ionic solvents, such as the l-butyl-3-methyl-imidazolium salts [169]. In order to establish the compatibihty of enzymes with ionic liquids, the hpase-catalyzed transesterification of 2-hydroxymethyl-1,4-benzodioxane was studied [170]. 

Imidazolium salts, di-N-condensed 12, 591 Imidazolone ring opening 15, 313... 

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