High-frequency spectroscopic study on the isomerization of a D-glucose aqueous solution

Saccharides have many hydroxyl groups in their molecular formulas and show mutarotation in aqueous solutions. Because of this, during the α,β isomerization of a D-glucose solution, a rearrangement of hydration occurs around the D-glucose molecules based on a stereochemical change of OH (1). High-frequency spectroscopy is an analytical method which is sensitive to the solution structures and/or a change of state of association between molecules. We applied the high-frequency method to the study of the α,β isomerization of D-glucose. The absorption intensity around 1800 MHz of high-frequency spectra was found to decrease with the progress of the isomerization reaction of D-glucose. The decrease of the intensity showed a linear relation with the reaction time. These results were found to agree with the rate of the reaction obtained from a rotation-angle measurement.