RELATIVE REACTIVITIES OF SUGARS IN THE FORMATION OF 5-HYDROXYMETHYLFURFURAL IN SUGAR-CATALYST MODEL SYSTEMS

Model systems were employed to determine the relative reactivity of sucrose, glucose, and fructose in the formation of 5‐hydroxymethylfurfural (5‐HMF) at pH 3.5. Fructose was the major reactant for formation of 5‐HMF. Fructose was 31.2 times faster than glucose, whereas sucrose was 18.5 times faster than glucose in the rate of 5‐HMF formation when averaged over three different sugar‐catalyst systems. Accelerating effects of citric acid, minerals (calcium, magnesium, and potassium), and amino acids (alanine, aspartic acid, and γ‐aminobutyric acid) in the formation of 5‐HMF from sugars were evaluated. With fructose as the substrate, 5‐HMF formed 5 times faster in the presence of citric acid and minerals than in the presence of HCl. Varying catalytic effects were noted with the three amino acids. Rates of 5‐HMF formation from glucose and sucrose showed slight enhancement in the presence of the amino acids, whereas virtually no enhancement occurred when fructose was the substrate. Copyright © 1990, Wiley Blackwell. All rights reserved