Deprotonation of β-cyclodextrin in alkaline solutions

Deprotonation of β-cyclodextrin in alkaline solutions

Variable pH 13C NMR and 1H NMR spectroscopic studies of the β-cyclodextrin (β-CD) in alkaline aqueous solutions revealed that β-CD does not deprotonate at pH < 12.0. Further increase in solution pH results in the deprotonation of OH-groups adjacent to C-2 and C-3 carbon atoms of β-CD glucopyranos...

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Veröffentlicht in:Carbohydrate research 2009-01, Vol.344 (2), p.250-254
Hauptverfasser: Gaidamauskas, Ernestas, Norkus, Eugenijus, Butkus, Eugenijus, Crans, Debbie C., Grincienė, Giedrė
Format: Artikel
Sprache:eng
Schlagworte:
13C NMR
1H NMR
beta-Cyclodextrins - chemistry
Deprotonation
Hydrogen-Ion Concentration
Molecular Structure
p Ka
Protons
β-Cyclodextrin
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Zusammenfassung:Variable pH 13C NMR and 1H NMR spectroscopic studies of the β-cyclodextrin (β-CD) in alkaline aqueous solutions revealed that β-CD does not deprotonate at pH < 12.0. Further increase in solution pH results in the deprotonation of OH-groups adjacent to C-2 and C-3 carbon atoms of β-CD glucopyranose units, whereas the deprotonation of OH-groups adjacent to C-6 carbon atoms is expressed less markedly. The p K a values for β-CD OH-groups adjacent to C-2 and C-3 carbon atoms are rather close, p K a1,2 being 13.5 ± 0.2 (22.5 °C).
ISSN:0008-6215
1873-426X
DOI:10.1016/j.carres.2008.10.025