title: Production of rare sugars from common sugars in subcritical aqueous ethanol.
abstract: A new isomerization reaction was developed to synthesize rare ketoses. D-tagatose, D-xylulose, and D-ribulose were obtained in the maximum yields of 24%, 38%, and 40%, respectively, from the corresponding aldoses, D-galactose, D-xylose, and D-ribose, by treating the aldoses with 80% (v/v) subcritical aqueous ethanol at 180°C. The maximum productivity of D-tagatose was ca. 80 g/(Lh). Increasing the concentration of ethanol significantly increased the isomerization of D-galactose. Variation in the reaction temperature did not significantly affect the production of D-tagatose from D-galactose. Subcritical aqueous ethanol converted both 2,3-threo and 2,3-erythro aldoses to the corresponding C-2 ketoses in high yields. Thus, the treatment of common aldoses in subcritical aqueous ethanol can be regarded as a new method to synthesize the corresponding rare sugars.
authors.affiliation: Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Da-Ming
authors.initials: DM
authors.lastname: Gao
authors.affiliation: Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. Electronic address: adachi@kais.kyoto-u.ac.jp.
authors.forename: Shuji
authors.initials: S
authors.lastname: Adachi
mesh_terms: D002241:Carbohydrates / Q000138:chemical synthesis / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry*; D006601:Hexoses / Q000737:chemistry; D007661:Ketoses / Q000138:chemical synthesis*; D010429:Pentoses / Q000737:chemistry; D014996:Xylulose / Q000737:chemistry
chemical_list: D002241:Carbohydrates; D006601:Hexoses; D007661:Ketoses; D010429:Pentoses; D000431:Ethanol; C100182:ribulose; D014996:Xylulose; C030192:tagatose
keywords: Ketose–aldose isomerization; Subcritical aqueous ethanol; d-Ribulose; d-Tagatose; d-Xylulose