| Abstract: | Several bases have been evaluated as catalysts for the production of d-psicose (d-ribo-2-hexulose) from d-fructose. The hexose levels in the isomerized mixtures were quantified by l.c. on a μBondapak/Carbohydrate column. The most effective and convenient base was found to be pyridine, and mixtures produced by boiling concentrated solutions (1 g/mL) of d-fructose in pyridine under reflux contained 12.4% of psicose, lesser proportions of glucose and mannose, and 25.8% of the starting material. Following removal of solvent, fermentation with bakers' yeast removed most hexoses other than d-psicose, which was isolated by chromatography on cellulose. The entire procedure required three days, and d-psicose was obtained in gram quantities in 6.8% of the theoretical yield. |
