Polymerization of DL-phenylalanine NCA initiated by copolymer of sarcosine and DL-phenylalanine

✍ Scribed by Yukio Imanishi; Toshiharu Sugihara; Toshinobu Higashimura

• Publisher: Wiley (John Wiley & Sons)
• Year: 1973
• Tongue: English
• Weight: 460 KB
• Volume: 12
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1973.360120706

✦ Synopsis

Abstract

Polymerizations of DL‐phenylalanine NCA by block copolymers of sarcosine and DL‐phenylalanine, designated by (Phe)~m~(Sar)n and capable of reaction at the phenylalanyl terminal, were investigated in nitrobenzene solution at 25°C. With increasing n for constant m (m = 0, 1, 2, and 5), the polymerization rate greatly increased. Previously the acceleration of the initiation reaction in the polymerization of DL‐phenylalanine NCA by polysarcosine (m = 0) was reported. The present results showing the acceleration by the copolymers of sarcosine and DL‐phenylalanine indicate the presence of the polymer effect in the propagation reaction as well. However, the polymer effect was most marked with polysarcosine (m = 0), and decreased with increasing m.

The same polymerizations by sequential copolymers composed of ten sarcosine units and two DL‐phenylalanine units were also investigated. Again with these copolymer catalysts the polymerization rate was larger than that by monomeric amines. But the polymer effect decreased sharply when the phenylalanine units take positions near the terminal amine group of the copolymer catalyst.

These two deteriorating effects of the phenylalanine unit have been interpreted in terms of the decrease of the flexibility of polymer chain, caused possibly by an intramolecular hydrogen bond of the phenylalanine unit.