Deprotonation of β-cyclodextrin in alkaline solutions

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• 作者：Ernestas Gaidamauskas ; Eugenijus Norkus ; Eugenijus Butkus ; Debbie C. Crans ; Giedrė ; Grincienė
• 关键词：β ; -Cyclodextrin ; Deprotonation ; pK_a ; ¹³C NMR ; ¹H NMR
• 刊名：Carbohydrate Research
• 出版年：2009
• 出版时间：26 January 2009
• 年：2009
• 卷：344
• 期：2
• 页码：250-254
• 全文大小：609 K

文摘

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 pK_a values for β-CD OH-groups adjacent to C-2 and C-3 carbon atoms are rather close, pK_a1,2 being 13.5 ± 0.2 (22.5 °C).