Table 1: Results for the isomerization/epimerization of sugars.

From: Sn-Beta zeolites with borate salts catalyse the epimerization of carbohydrates via an intramolecular carbon shift

EntrySugarSugar:SB(mol:mol)CatalystTemperature(K)Time(min)Conversion*(%)Product distributionTotal sugar
ReagentIsomerEpimerYield
       (%)(%)(%)(%)
       GlucoseFructoseMannose 
1Glucose4:1None35860110099
2Glucose4:1Si-Beta35860110099
3Mannose4:1None3586020010098
4Glucose§4:1Sn-Beta35860168411599
5GlucoseSn-Beta35830218316195
6Mannose4:1Sn-Beta35860171408697
           
       XyloseXyluloseLyxose 
7Xylose§4:1Sn-Beta35815307532293
8XyloseSn-Beta35815247913896
9Xylose4:1Sn-Beta333120218111897
10XyloseSn-Beta333120188371098
           
       ArabinoseRibuloseRibose 
11Arabinose§4:1Sn-Beta35815346813197
12ArabinoseSn-Beta35815308411583
13Arabinose4:1Sn-Beta333120178411599
14ArabinoseSn-Beta33312011915495
  1. Reactions were performed with a 5 wt% sugar feed (~2 ml), using the corresponding amount of catalyst to maintain a 100:1 sugar:metal molar ratio (~40 mg).
  2. *Conversion is defined as the ratio of moles of sugar consumed to moles sugar added initially, expressed as a percentage.
  3. Product distribution is the molar ratio of each sugar to the sum of the three sugars expressed as a percentage.
  4. Sugar yield is the ratio of the sum of moles of the reagent, isomer and epimer sugars to moles of sugar added initially, expressed as a percentage.
  5. §The epimerization product distributions at the thermodynamic equilibrium are: Glucose:Mannose=70:30, Xylose:Lyxose=67:33, and Arabinose:Ribose=69:31. Values obtained from Gibbs free energies reported by Angyal46.
  6. For this entry the Reagent and Epimer columns in the product distribution are exchanged so that they match the type of sugar used.