Abstract
In the presence of 2,6-dimethylpyridine as an added base, living cationic polymerization of isobutyl vinyl ether was achieved in n-hexane at 0 to +40°C with the 1-(isobutoxy)ethyl acetate (3)/ethylaluminum dichloride [CH3CH(OiBu)-OCOCH3/EtAlCl2] initiating system. A low concentration of the pyridine, 4 times that of the cationogen 3 (or the active end), was sufficient for the living process. Without the added amine, the polymerization was almost instantaneous and nonliving. The use of triethylamine and less hindered pyridines (pyridine, 2-methylpyridine, and 2,4-dimethylpyridine), in place of the 2,6-dimethyl derivative, failed to induce living polymerization but instead resulted in chain termination. In contrast, highly crowded 2,3-di-t-butylpyridine could not affect the polymerization by 3/EtAlCl2 at all. It is proposed that 2,6-dimethylpyridine stabilizes the otherwise unstable growing carbocation via a nucleophilic interaction to endow it with livingness. The effects of the pyridine structures showed not the basicity but the steric crowding around the nitrogen to play a critical role in the nucleophilic stabilization of the growing cation.
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For a review, see: T. Higashimura, M. Sawamoto, and S. Aoshima, Makromol. Chem., Makromol. Symp., 13/14, 457 (1988).
S. Aoshima and T. Higashimura, Polym. Bull., 15, 417 (1986).
S. Aoshima and T. Higashimura, Macromolecules, in press.
T. Higashimura, Y. Kishimoto, and S. Aoshima, Polym. Bull., 17, 111 (1987).
Y. Kishimoto, S. Aoshima, and T. Higashimura, Macromolecules, submitted (Part IV of this series).
D. D. Eley and J. Saunders, J. Chem. Soc., 1672 (1954).
J. George, H. Wechsler, and H. F. Mark, J. Am. Chem. Soc., 72, 3891 (1950).
G. F. Endres and C. G. Overberger, J. Am. Chem. Soc., 77, 2201 (1955).
S. Okamura and T. Higashimura, J. Polym. Sci., 21, 289 (1956).
D. H. Jenkinson and D. C. Pepper, Proc. Chem. Soc. (London), A263, 82 (1961).
A. Gero and J. J. Markham, J. Org. Chem., 16, 1835 (1951).
J. C. Gage, J. Chem. Soc., 469 (1949).
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Higashimura, T., Okamoto, S., Kishimoto, Y. et al. Living Cationic Polymerization of Vinyl Monomers by Organoaluminum Halides V. Polymerization of Isobutyl Vinyl Ether with EtAlCl2 in the Presence of 2,6-Dimethylpyridine and Related Amines. Polym J 21, 725–732 (1989). https://doi.org/10.1295/polymj.21.725
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DOI: https://doi.org/10.1295/polymj.21.725