Reaction pathways of glucose oxidation by ozone under acidic conditions.
The ozonation of d-glucose-1-(13)C, 2-(13)C, and 6-(13)C was carried out at pH 2.5 in a semi-batch reactor at room temperature. The products present in the liquid phase were analyzed by GC-MS, HPAEC-PAD, and (13)C NMR spectroscopy. Common oxidation products of glucose have also been submitted to identical ozonation conditions. For the first time, a pentaric acid was identified and its formation quantitatively correlated to the loss of C-6 of glucose in the form of carbon dioxide. Potential mechanisms for the formation of this pentaric acid are discussed. The well-accepted pathway involving the anomeric position in glucose, gluconic acid, arabinose, and carbon dioxide is reinvestigated. The origin of small molecules such as tartaric, erythronic, and oxalic acids is clarified. Finally, new reaction pathways and tentative mechanisms consistent with the formation of ketoaldonic acids and smaller acids are proposed.
Marcq
Olivier
O
ICMUB-LIMRES (UMR 5260), Université de Bourgogne, Faculté des Sciences Mirande, F- 21100 Dijon, France.
Barbe
Jean-Michel
JM
Trichet
Alain
A
Guilard
Roger
R
D001089:Arabinose / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D002245:Carbon Dioxide / Q000737:chemistry; D005942:Gluconates / Q000737:chemistry; D005947:Glucose / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D010126:Ozone / Q000737:chemistry*
D005942:Gluconates; D002245:Carbon Dioxide; D010126:Ozone; D002244:Carbon; D001089:Arabinose; D005947:Glucose; C030691:gluconic acid