Activation of TEMPO by ClO2 for oxidation of cellulose by hypochlorite-Fundamental and practical aspects of the catalytic system

Timo Pääkkönen; Raili Pönni; Jinze Dou; Markus Nuopponen; Tapani Vuorinen

doi:10.1016/j.carbpol.2017.06.117

Activation of TEMPO by ClO₂ for oxidation of cellulose by hypochlorite-Fundamental and practical aspects of the catalytic system

Carbohydr Polym. 2017 Oct 15:174:524-530. doi: 10.1016/j.carbpol.2017.06.117. Epub 2017 Jun 30.

Authors

Timo Pääkkönen¹, Raili Pönni², Jinze Dou³, Markus Nuopponen⁴, Tapani Vuorinen⁵

Affiliations

¹ Aalto University, School of Chemical Engineering, Department of Bioproducts and Biosystems, P.O. Box 16300, 00076 Aalto, Finland. Electronic address: timo.paakkonen@aalto.fi.
² Aalto University, School of Chemical Engineering, Kemistintie 1, P.O. Box 16100, 00076 Aalto, Finland. Electronic address: raili.ponni@aalto.fi.
³ Aalto University, School of Chemical Engineering, Department of Bioproducts and Biosystems, P.O. Box 16300, 00076 Aalto, Finland. Electronic address: jinze.dou@aalto.fi.
⁴ UPM Biochemicals, Biomedicum 2U, Tukholmankatu 8, 00290 Helsinki, Finland. Electronic address: markus.nuopponen@upm.com.
⁵ Aalto University, School of Chemical Engineering, Department of Bioproducts and Biosystems, P.O. Box 16300, 00076 Aalto, Finland. Electronic address: tapani.vuorinen@aalto.fi.

PMID: 28821100
DOI: 10.1016/j.carbpol.2017.06.117

Abstract

Bromide-free TEMPO-catalyzed oxidation of the primary alcohols by sodium hypochlorite (NaOCl) does not proceed without a prior activation of the catalyst. Here were demonstrate an immediate in situ activation of the catalyst with an equimolar addition of chlorine dioxide (ClO₂) relative to TEMPO. Sodium bromide (NaBr) had a similar role in activating the catalyst although NaBr was needed in excess and the activation took several minutes depending on the dosage of NaBr. The activation method, or the concentration of NaBr, did not affect the bulk oxidation rate. The selectivity of the ClO₂ initiated oxidation remained high up to NaOCl addition of 3mol/kg bleached birch kraft pulp after which additional loss in yield and depolymerization of cellulose were emphasized with negligible increase in carboxylate content. A carboxylate content of 0.8-1mol/kg, sufficient for easy mechanical fibrillation of the pulp, was achieved under mild conditions with NaOCl addition of 2-2.5mol/kg pulp.

Keywords: 2,2,6,6-Tetramethyl-1-piperidinyloxy (PubChem CID: 2724126); Birch pulp; Bromide-free; Carboxylates; Cellulose; Chlorine dioxide (PubChem CID: 24870); ClO(2) activated TEMPO-mediated oxidation; Hydrochloric acid (PubChem CID: 313); Sodium chlorite (PubChem CID: 23668197); Sodium hydroxide (PubChem CID: 14798); Sodium hypochlorite (PubChem CID: 23665760); UV–vis spectrometry.