PROMOTED ISOMERIZATION OF ALDOSES TO KETOSES IN SUBCRITICAL AQUEOUS ACETONITRILE

Isomerizations of D-glucose, D-mannose, D-fructose, D-galactose, D-xylose, D-ribose, cellobiose, maltose, lactose, and melibiose were investigated in subcritical aqueous acetonitrile. D-Glucose and D-mannose were preferred to be isomerized to D-fructose, while D-fructose mainly underwent decomposition rather than isomerization. Effects of acetonitrile concentration and temperature on saccharide isomerization were investigated using glucose as a substrate. The conversion of D-glucose and yield of D-fructose were improved with increasing acetonitrile concentration at 180 to 200 degrees C. In attempts to produce rare ketoses simply, D-tagatose, D-xylulose, D-ribulose, cellobiulose, maltulose, lactulose, and melibiulose were successfully produced in high yields and selectivities by treating their corresponding aldoses with subcritical aqueous acetonitrile.