Interaction of potassium fluoride with alpha-D-glucose

Addition of KF to solutions of alpha -D-glucose (alpha DG) in DMSO-d(6) and D2O alters the H-1 NMR spectra, which is attributed to an interaction of t he hydrogen atoms of the -OH groups with the basic F- anions of the salt. I t is shown that K+ cations do not interact with the oxygen atoms of the -OH groups of the alpha DG. Mutarotation rates Of alpha DG in D2O in the prese nce of potassium halides and alkaline chlorides were measured from the inte grated C-13 NMR signal of the anomeric protons. The mutarotation rates were higher with KF than other potassium halides. In order to shed light on the interactions of KF with the alpha DG, the mutarotation Of alpha DG in the presence of KF and KOH were also studied using polarimetric measurements. A t similar pH values, the effect of KF on the mutarotation rate is about fiv e times that observed for KOH, indicating a major affinity for the F- anion by the anomeric proton as compared with OH-. The acceleration of the mutar otation process Of alpha DG is evidence for KF-alpha DG interactions, since NMR spectra of beta conformer are also altered by the presence of KF. (C) 2001 Elsevier Science B.V. All rights reserved.