In the past decade, research on organocatalysis using organic compounds as catalysts has been actively studied in polymer synthesis. Anionic polymerization of methyl methacrylate (MMA) catalyzed by N-heterocyclic carbene (NHC) is already reported. In our laboratory, we polymerized alkyl sorbates assisted by NHC in some organic solvents. The current study specifically forcuses on a commonly used NHC, 1,3-di-tert-butylimidazolin-2-yildene (ItBu). In N, N-dimethylformamide (DMF) at 25 °C, poly (methyl sorbate) [poly(MS)] with number-averaged molecular weight (Mn) of 3.5 × 103 (Mw / Mn = 2.1) was obtained in conversion of 93 %. The structure was confirmed by 1H and 13C NMR and IR spectra, which revealed that the propagation proceeded via 1,2-addition as well as 1,4-addition. In toluene, although the polymerization did not occur in the absence of any additive, complete monomer consumption was observed in the presence of methylaluminum bis(2,6-di-tert-butyl-4-methylphenoxide) (MAD) to afford the poly(MS) with 1,4-trans structure with Mn of 19.1 × 103 (Mw / Mn = 2.4). Next, the polymer obtained was hydrogenated to remove the influence of magnetic anisotropy, and we confirmed that the diastereoselecivity of the polymer was controlled. As the result, 88% of threo diastereoselectivity was observed. Finally, we also examined the possibility of ring-closing of backbiting of the growing ester enolate to the nucleophilic carbon directly bonded to the NHC. In the presentation, we will report the results of ring-closing to afford cyclic poly(MS).

Anionic polymerization of (E,E)-alkyl sorbate assisted by N-heterocyclic carbene (NHC)

254th National Meeting (2017)

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