Recoverable, water-soluble polyethylene glycol-immobilized N-hydroxyphthalimide, as mediator for cellulose oxidation in the presence of NaBr and NaClO

Autor: Tingting Sun, Xiaomeng Chu, Xiaoying Wang, Erjun Tang, Shaojie Liu, Peixin Li, Xuteng Xing, Huimin Wang
Rok vydání: 2021
Předmět:
Zdroj: Cellulose. 28:11315-11328
ISSN: 1572-882X
0969-0239
DOI: 10.1007/s10570-021-04263-1
Popis: As a highly efficient nitroxide radical catalyst for selective catalytic oxidation of cellulose, N-hydroxyphthalimide (NHPI) has attracted much attention because of its low price and light cellulose degradation. However, NHPI is insoluble in water and is difficult to recycle because of its small molar mass. To address the above issues, the water-soluble polyethylene glycol (PEG)-immobilized NHPI catalyst (PEG-NHPI) was designed and prepared in this work. Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), size exclusion chromatography (SEC) and UV–Vis light spectrophotometry were used to characterize PEG-NHPI. The results showed that PEG-NHPI catalysts with good water solubility and adjustable NHPI loading amounts were successfully synthesized. Using NaBr as promoter and NaClO as oxidant, PEG-NHPI mediated oxidation of cellulose was carried out and good catalytic performance was found. The catalytic performance of PEG-NHPI mediated oxidation of cellulose in water was higher than that in acetonitrile–water. The carboxyl content of PEG-NHPI oxidized cellulose could reach the level of free NHPI oxidized cellulose, and was equivalent to 68% of 2, 2, 6, 6-tetramethylpiperidine-N-oxyl (TEMPO) oxidized cellulose, while the degradation degree of cellulose was greatly reduced by more than 40%. The catalytic performance did not decrease significantly after six oxidation cycles. The structure of recycled PEG-NHPI was not changed. These results indicated that immobilizing NHPI onto PEG can achieve the unification of high catalytic performance and good recyclability.
Databáze: OpenAIRE
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