The catalyzed polymerization of 1,2-anhydro-3,4,6-tri-O-acetyl-α-D-glucopyranose
| Autor: | Jaromir Zachoval, Conrad Schuerch |
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| Rok vydání: | 2007 |
| Předmět: | |
| Zdroj: | Journal of Polymer Science Part C: Polymer Symposia. 28:187-195 |
| ISSN: | 1935-3065 0449-2994 |
| DOI: | 10.1002/polc.5070280116 |
| Popis: | The polymerization of Brigl's anhydride, 1,2-anhydro-3,4,6-tri-O-acetyl-α-D-glucopyranose, proceeds readily at temperatures from −100 to +25°C when catalyzed or initiated by Lewis acids or carbonium ions. The products generally consist of a sol fraction of number average degree of polymerization three to five and sometimes a gel fraction. The latter appears to be crosslinked through ortho acetate structures. Usually the soluble products exhibit a high positive optical rotation indicating a predominance of α linkages. The product with highest optical rotation, [α] + 186.5°, was obtained by catalysis with BF3 etherate in methylene chloride at 0°C. In most systems the molecular weight and the optical activity of products showed variations but no significant trends with changes in temperature of polymerization. Reaction probably proceeds by growth on a carbonium ion in an ion pair. |
| Databáze: | OpenAIRE |
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