ISSN:
0025-116X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Selective sulfation of the primary hydroxyl group of chitosan was performed by means of the pyridine-SO3 complex after the positions 2 and 3 of the aminoglucopyranosidic ring were protected by coordination with copper ions. The requirements for complexing copper ions were investigated as a function of the pH and Cu(II)/chitosan mole ratio of the starting solution. Cu(II)-chitosan complexes were characterized by ESR and 13C NMR CP-MAS investigations; two different paramagnetic Cu(II) species were observed, whose relative quantity changes by changing the pH of the starting solution. The g tensor values (species I: g1‖ = 2,28, g1‖ = 2,06, A2‖ = 160 G; species II; g2‖ = 2,24, g2‖ = 2,06, A2‖ = 160 G) are consistent with a CuN2O2 chromophore. The sulfation reaction was studied in the range of 25 to 75°C using 2 : 1 to 6 : 1 pyridine-SO3/Cu(II)-chitosan mole ratios. Under optimized reaction conditions, a selective 6-O sulfation was obtained in more than 90% yield.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/macp.1986.021871110
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