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Catalytic Transfer Hydrogenation of Glucose‐Fructose Syrups in Alkaline Solution
Author(s) -
van Hengstum A. J.,
Kieboom A. P. G.,
van Bekkum H.
Publication year - 1984
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.19840360908
Subject(s) - chemistry , gluconic acid , sorbitol , catalysis , mannitol , fructose , dehydrogenation , inorganic chemistry , aqueous solution , chromatography , organic chemistry
Equimolar mixtures of glucose and fructose were found to undergo quantitative transfer hydrogenation yielding equal amounts of gluconic acid and of hexitols (mannitol and sorbitol). The oxidationreduction occurs in aqueous alkaline medium under nitrogen at room temperature in the presence of Pt/C or Rh/C as the catalyst. Other group VIII metals did not give satisfactory results. Both a stirred batch and a continuous flow column reactor have been applied. The influence of several reaction variables has been studied, leading to the conclusion that the rate‐limiting step ist the dehydrogenation reaction of glucose into gluconic acid and chemisorbed hydrogen. Subsequently, the latter is quickly consumed by coadsorbed fructose under formation of mannitol and sorbitol (in the ratio of 1.5. – 1.9: 1). Alkaline degradation products are found to be of minor importance at temperatures ≦ 25°C.