TAUTOMERIC EQUILIBRIA OF D‐GLUCOSE AND D‐FRUCTOSE: NMR SPECTROMETRIC MEASUREMENTS

Abstract

ABSTRACTThe influence of temperature and concentration on the anomeric equilibrium of glucose was determined by 1H NMR spectrometry and on the tautomeric equilibrium of fructose by 1 3C Fourier transformation NMR spectrometry. The proportion of the ol‐anomer at the equilibria of glucose solutions was approximately constant at 5% and 10% concentrations at different temperatures. At higher concentrations (20, 50 and 65%) the proportion of the cy‐anomer at equilibrium was increased at higher temperatures. The proportion of both α‐ and β‐fructofuranoses was increased at the equilibrium of 20% fructose solutions at higher temperatures. The tautomeric equilibrium of fructose remained approximately unchanged in the 20, 50 and 80% fructose solutions at room temperature.