Oxidation of regenerated cellulose with NaClO2 catalyzed by TEMPO and NaClO under acid-neutral conditions
2009; Elsevier BV; Volume: 78; Issue: 2 Linguagem: Inglês
10.1016/j.carbpol.2009.04.012
ISSN1879-1344
AutoresMasayuki Hirota, Naoyuki Tamura, Tsuguyuki Saito, Akira Isogai,
Tópico(s)Lignin and Wood Chemistry
ResumoA new TEMPO-mediated oxidation with catalytic amounts of TEMPO and NaClO, and NaClO2 as the primary oxidant under aqueous conditions at pH 3.5–6.8 was used to prepare water-soluble β-(1 → 4)-linked polyglucuronic acid Na salts (cellouronic acids, CUAs) with high molecular weight in good yield. When regenerated cellulose with original degree of polymerization (DP) of 680 was oxidized by the 4-acetamide-TEMPO/NaClO/NaClO2 system at pH 5.8 and 40 °C for 3 days, CUA with weight average DP (DPw) of 490 was obtained quantitatively. No peaks other than six signals from β-(1 → 4)-linked anhydroglucuronic acid units of CUA were detected in the solution-state 13C NMR spectra of the oxidized products. Although the oxidized product prepared under the above conditions contained about 20% unoxidized cellulose particles, the non-CUA fraction was separable from CUAs by filtration or salt precipitation. The DPw values and yields of CUAs after the filtration or salt precipitation treatment were 250–380 and 45–71%, respectively.
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