Interaction of potassium fluoride with α-d-glucose

Addition of KF to solutions of α-D-glucose (αDG) in DMSO-d₆ and D₂O alters the ¹H NMR spectra, which is attributed to an interaction of the hydrogen atoms of the -OH groups with the basic F^- anions of the salt. It is shown that K⁺ cations do not interact with the oxygen atoms of the -OH groups of the αDG. Mutarotation rates of αDG in D₂O in the presence of potassium halides and alkaline chlorides were measured from the integrated ¹³C 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 αDG, the mutarotation of αDG in the presence of KF and KOH were also studied using polarimetric measurements. At similar pH values, the effect of KF on the mutarotation rate is about five 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 mutarotation process of αDG is evidence for KF-αDG interactions, since NMR spectra of β conformer are also altered by the presence of KF.