Abstract
Polymerizations of DL-phenylalanine N-carboxyanhydride (NCA) by pyridine, 2,2′-bipyridine, 4,4′-bipyridine, 2,2′,2''-tripyridine, 2,2′,2'',2'''-tetrapyridine were carried out in nitrobenzene at 35°C. When the aprotic base was in excess of NCA, the initial polymerization rate increased with increasing the basicity of the aprotic base. When NCA was in excess of the aprotic base, 2,2′-bipyridine led to the fastest polymerization. Since pyridine groups act as adsorption sites as well as catalytic sites, a cooperative function of two pyridine groups in bifunctional 2,2′-bipyridine is suggested. LCAO–MO calculations showed the possibility that two reacting species are adsorbed on 2,2′-bipyridine. Since they are arranged suitably for intramolecular collisions, the reaction rate increases. In the polymerization of DL-phenylalanine NCA by n-hexylamine in the presence of 2,2′-bipyridine as a matrix, the same sort of acceleration was also observed.
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Imanishi, Y., Nagaoka, S. & Higashimura, T. Polymerization of DL-Phenylalanine N-Carboxyanhydride by Multifunctional Pyridine Derivatives. Polym J 4, 644–650 (1973). https://doi.org/10.1295/polymj.4.644
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DOI: https://doi.org/10.1295/polymj.4.644