Efficient oxidative modification of polysaccharides in water using H2O2 activated by iron sulfophthalocyanine

Selective and environmentally friendly oxidation of polysaccharides by hydrogen peroxide in the presence of iron tetrasulfophthalocyanine (FePcS) catalyst was studied in aqueous media. Oxidation under mild conditions led to the cleavage of the C-C bond of vicinal diols of glycoside units as a result of carbonyl and carboxyl formation. Optimized experimental conditions allowed oxidation of hydroxyethylcellulose (HEC), sodium carboxymethyl cellulose (NaCMC), guar gum (GG), and inulin to the extent of 19, 30, 53, 23 carbonyl functions per 100 anhydroglucose units, respectively. Possible explanation for this relatively modest conversion is discussed. Over-oxidation phenomena appear to play an important role during the oxidation process. (C) 2009 Elsevier Ltd. All rights reserved.