ClO₂-Mediated Oxidation of the TEMPO Radical: Fundamental Considerations of the Catalytic System for the Oxidation of Cellulose Fibers

Abstract

The reaction mechanism of ClO2-mediated TEMPO oxidation was investigated by EPR spectroscopy and UV–Vis spectroscopy in the context of an alternative TEMPO sequence for cellulose fiber oxidation. Without the presence of a cellulosic substrate, a reversibility between TEMPO and its oxidation product, TEMPO+, was displayed, with an effect of the pH and reagent molar ratios. The involvement of HOCl and Cl−, formed as byproducts in the oxidation mechanism, was also evidenced. Trapping HOCl partly inhibits the reaction, whereas adding methylglucoside, a cellulose model compound, inhibits the reversibility of the reaction to TEMPO.

Keywords

• TEMPO oxidation
• chlorine dioxide
• EPR spectroscopy
• UV–Vis spectroscopy