Alkylidenation of fructose with perfluorinated acid catalysts

Abstract

Aqueous fructose and aldehydes, ketones and/or acetals may be effectively catalyzed into alkylidene fructose derivatives with immobilized acid catalysts. The reaction provides a means for enriching the fructose content of conventional high fructose corn syrups. Perfluorinated acid resins are especially effective catalysts for converting aqueous fructose and acetone solutions into diacetone fructose. Catalysis with the perfluorinated acid resins may be conducted at significantly lower conversion temperatures with superior reactant and reaction product exchange rates. Enrichment of high fructose corn syrups may be generally accomplished by catalyzing the fructose and acetone into a diacetone fructose solution with the perfluorinated acid resin, allowing the dextrose to precipitate from the diacetone solution, hydrolyzing the diacetone fructose to fructose and recovery of the enriched fructose product therefrom. The water-insoluble catalysts afford a reusable catalyst system which can be easily separated from the processed products. The perfluorinated acid resins produce a high quality, food-grade syrup products essentially free of ash, organoleptic bodies (e.g. flavoring, coloring, etc.) and other objectionable by-product contaminants.