Analysis of carboxylate groups in oxidized never-dried cellulose II catalyzed by TEMPO and 4-acetamide-TEMPO

Kai Zhang; Steffen Fischer; Andreas Geissler; Erica Brendler

doi:10.1016/j.carbpol.2011.08.090

Analysis of carboxylate groups in oxidized never-dried cellulose II catalyzed by TEMPO and 4-acetamide-TEMPO

Carbohydr Polym. 2012 Jan 4;87(1):894-900. doi: 10.1016/j.carbpol.2011.08.090. Epub 2011 Sep 3.

Authors

Kai Zhang¹, Steffen Fischer², Andreas Geissler², Erica Brendler³

Affiliations

¹ Institute of Plant and Wood Chemistry, Dresden University of Technology, Pienner Str. 19, D-01737 Tharandt, Germany. Electronic address: kzhang@forst.tu-dresden.de.
² Institute of Plant and Wood Chemistry, Dresden University of Technology, Pienner Str. 19, D-01737 Tharandt, Germany.
³ Institute of Analytical Chemistry, Freiberg University of Mining and Technology, Leipziger Str. 29, D-09599 Freiberg, Germany.

PMID: 34663051
DOI: 10.1016/j.carbpol.2011.08.090

Abstract

In this report, never-dried regenerated celluloses, i.e. cellulose II, from their NaOH/urea/H₂O solutions were subjected to TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) or 4-acetamide-TEMPO-mediated oxidation. Water-soluble and -insoluble fractions of carboxyl cellulose (COC) were obtained and their DO were determined to be between 0.08 and 0.85. Apart from conductometric titration, complexometric titration with EDTA was used to analyze the DO of COC. The conductometric titration can be used for lowly or highly oxidized celluloses, while the complexometric titration with EDTA is only adequate for COC with DO lower than 0.6. FT Raman spectroscopy represents characteristic bands of carboxyl and carboxylate groups. It demonstrates the feasibility of establishing novel analyzing methods for DO of COC with high correlation coefficients of up to 0.9867. Moreover, long oxidation duration, high temperature and high amounts of oxidizing agents are important for the synthesis of COC with high DO and yields.

Keywords: Carboxyl cellulose; Degree of oxidation (DO); FT Raman spectroscopy; Oxidation; TEMPO.