Ring-opening polymerization of cyclic carbonates by alcohol–acid catalyst

✍ Scribed by Jyuhou Matsuo; Shinji Nakano; Fumio Sanda; Takeshi Endo

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 180 KB
• Volume: 36
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(199810)36:14<2463::aid-pola4>3.0.co;2-u

✦ Synopsis

Ring-opening reactions of 1,3-dioxepan-2-one (1) and 1,3-dioxan-2-one (2) with several alcohols were examined. The reactions proceeded without trifluoroacetic acid (TFA) in low conversions, while they proceeded smoothly with TFA to afford the ring-opened adducts and oligomers. Ring-opening polymerizations of 1 and 2 were also carried out by alcohol-acid catalysts to afford the corresponding polycarbonates (M n ϭ 2500 -6800). The molecular weights increased with increase of the conversions of 1 and 2. The observed polymerization rates of 1 and 2 were determined as 24.4 ϫ 10 Ϫ6 and 0.8 ϫ 10 Ϫ6 s Ϫ1 , respectively. Mechanistic aspects were studied by NMR spectroscopy. The methylene protons ␣ and ␤ to the carbonate moieties shifted to lower fields in 0.06 -0.11 ppm in the 1 H-NMR spectra by the addition of TFA. Downfield shifts of the carbonyl carbon signals of 1 and 2 were observed in 3.94 -4.15 ppm in the 13 C-NMR spectra. These results strongly suggest that the cyclic carbonates are activated by TFA.