College of Chemistry, Sichuan University, Chengdu 610065, China.
Jingkun Oilfield Chemistry Technology Development Company, Suzhou 215300, China.
Molecules. 2020 Oct 14;25(20):4698. doi: 10.3390/molecules25204698.
C-6 oxidized chitosan is of great interest in obtaining a new moisture retention polymer like hyaluronic acid. The direct C-6 specific oxidation of chitosan mediated by the TEMPO/NaClO/NaBr system has proven to be difficult because of the high crystalline and high C-2 amino group content. In this work, the pre-modification of chitosan by -succinylation was investigated and followed by the TEMPO-mediated C-6 specific oxidation under homogeneous conditions. The desired 6-oxidized -succinyl chitosan product was obtained within 15 min with a yield of about 92%. The structure of these chitosan derivatives was confirmed by FTIR and NMR spectroscopy. Moreover, it was observed that the selective oxidation led to a great improvement in water solubility and moisture retention ability. These results present a wide range of possibilities for expanding the utilization of chitosan resources.
C-6 氧化壳聚糖在获得具有保湿性能的类似透明质酸的新型聚合物方面具有很大的吸引力。由于壳聚糖具有较高的结晶度和高 C-2 氨基含量，通过 TEMPO/NaClO/NaBr 体系介导的 C-6 特异性氧化反应直接氧化壳聚糖是很困难的。在这项工作中，研究了通过 -琥珀酰化对壳聚糖进行预修饰，然后在均相条件下通过 TEMPO 介导进行 C-6 特异性氧化。在 15 分钟内获得了所需的 6-氧化 -琥珀酰壳聚糖产物，产率约为 92%。这些壳聚糖衍生物的结构通过傅里叶变换红外光谱和核磁共振波谱得到了确认。此外，观察到选择性氧化导致水溶性和保湿能力有了很大的提高。这些结果为扩大壳聚糖资源的利用提供了广泛的可能性。
