Research Article
Intramolecular Lactonization of Poly(α-hydroxyacrylic acid): Kinetics and Reaction Mechanism
Table 1
Assignment of the 1H shifts (at intensity maximum) and their average deviations (ad) of the acyclic and lactonized structures of PHA at pH 1–9.
| pH | Acyclic PHA ppm | ad | Lactonized PHA ppm | ad |
| 1 | 2.18–2.26 | 0.04 | n/a–2.84 | n/a | 2 | 2.17–2.24 | 0.04 | n/a–2.79 | n/a | 3 | 2.18–2.24 | 0.03 | 2.53–2.78 | 0.13 | 4 | 2.10–2.22 | 0.06 | 2.47–2.68 | 0.11 | 4.5 | 2.07–2.20 | 0.07 | 2.44–2.67 | 0.12 | 5 | 2.03–2.13 | 0.05 | 2.47–2.62 | 0.08 | 6 | 1.98–2.00 | 0.01 | 2.42–2.46 | 0.02 | 7 | 1.97–1.99 | 0.01 | n/a-n/a | n/a | 8 | 1.97–1.98 | 0.01 | n/a-n/a | n/a | 9 | 1.97–1.98 | 0.01 | n/a-n/a | n/a |
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