Ring-opening polymerization of six- and seven-membered cyclic pseudoureas

✍ Scribed by Masatoshi Miyamoto; Keigo Aoi; Takeo Saegusa

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 277 KB
• Volume: 35
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(19970415)35:5<933::aid-pola8>3.0.co;2-l

✦ Synopsis

The cationic ring-opening polymerization of six-membered cyclic pseudoureas, 2-(1-pyrrolidinyl)-( 2a) and 2-morpholino-5,6-dihydro-4H-1,3-oxazine ( 2b), was examined, which proceeded in two different ways, depending on the nature of initiator. The polymerization of 2 with methyl p-toluenesulfonate or trifluoromethanesulfonate (MeOTf) produced poly[(N-carbamoylimino)trimethylene], while that with benzyl chloride or bromide or methyl iodide gave a polymer consisting of 1,3-diazin-2-one-1,3diylalkylene unit (the main component) and ( N-carbamoylimino)trimethylene unit. The cationic ring-opening polymerization of seven-membered cyclic pseudourea, 2-(1pyrrolidinyl)-4,5,6,7-tetrahydro-4H-1,3-oxazepine ( 3) was also examined. The polymerization of 3 with MeOTf as initiator gave poly{[N-(1-pyrrolidinycarbonyl)imino]tetra-methylene}. With benzyl chloride, on the other hand, no polymerization of 3 proceeded but, instead, the quantitative isomerization of 3 to 1,1-carbonyldipyrrolidine took place. The polymerization mechanism of 2 and 3 as well as the isomerization mechanism of 3 were discussed with comparing them to the polymerization mechanism of fivemembered pseudoureas.