TEMPO-mediated oxidation of maltodextrins and d-glucose: effect of pH on the selectivity and sequestering ability of the resulting polycarboxylates

Improved preparative electrochemical oxidation of d-glucose to d-glucaric acid

“…As carbohydrate chemical oxidation reactions are rather sensitive to pH and temperature variations [14], we studied the influence of these parameters on such electrochemical oxidation. Electrolysis of d-glucose and TEMPO in a sodium carbonate solution using a glassy carbon electrode at different pH (7.2-12.2) showed an important variation in the current peak intensity.…”

“…Much of our attention was directed toward such oxidation methods when we described several improved preparative syntheses of d-glucaric acid from d-glucose using chemical methods involving the TEMPO/NaBr/NaOCl and later the TEMPO/NaBr/Cl 2 system [3,12,14].…”

“…While the electrochemical behavior of TEMPO in such oxidation has been extensively studied [15][16][17][18][19], few preparative electrochemical oxidations of d-glucose are described in the literature, leaving the door open for such studies [20]. Our objective was the development of an eletrochemical oxidation method based on the work of Thaburet et al while decreasing the amount of undesired side-products [14,21].…”

Partial and total C-6 oxidation of gelling carrageenans. Modulation of the antiviral activity with the anionic character

“…in catalytic amounts by the addition of another oxidant (usually NaOCl or commercial bleach) which regenerates the nitroxyl oxidant (Bragd, van Bekkum, & Besemer, 2004). With an adequate pH regulation to avoid oxidation by the hypochlorite, selective C-6 oxidation was achieved for different polysaccharides like cellulose (Follain, Montanari, Jeacomine, Gambarelli, & Vignon, 2008;Xu, Dai, Sun, Wang, & Wu, 2012) and starch (Bragd, Besemer, & van Bekkum, 2001;de Nooy, Besemer, & van Bekkum, 1995;Kato, Matsuo, & Isogai, 2003;ter Haar et al, 2010;Thaburet, Merbouh, Ibert, Marsais, & Queguiner, 2001), among many others. Recently, the C-6 oxidation of agarose (Su et al, 2013), a polysaccharide related to carrageenan, was reported.…”

Evidence of benzilic rearrangement during the electrochemical oxidation of d-glucose to d-glucaric acid

“…These oxidations, when performed with sodium hypochlorite or chlorine as an oxidant afforded high purity D-glucaric acid in yields up to 85%. [1][2][3][4] A thorough study of these reactions' side-products led us to a better understanding of the oxidations and degradation pathways occurring, along with the development of quick and efficient methodologies to analyze the complicated reaction mixtures often obtained during such oxidations. 5 Subsequently, we described the TEMPO-catalyzed electrochemical oxidation of D-glucose to D-glucaric acid.…”