中文摘要：

TEMPO/NaClO/NaBr氧化体系被广泛应用于选择性氧化糖类C6位伯醇羟基,使其成为羧酸盐物质,从而获得更好的水溶性或其他特定功能。但在氧化反应过程中,pH随反应的进行下降,并且存在pH值持续控制繁琐等问题。实验比较分析TEMPO/NaClO/NaBr氧化纤维素在碳酸钠―碳酸氢钠缓冲溶液、硼砂―氢氧化钠缓冲溶液中的适用性,并以滴加的方式向体系中加入氧化剂NaClO溶液,探索两种缓冲体系中各自适宜的NaClO滴加速度。实验结果表明,碳酸钠―碳酸氢钠缓冲溶液和硼砂―氢氧化钠缓冲溶液都适用于TEMPO/NaClO/NaBr氧化体系。与传统方法相比,氧化纤维素的羧基含量可以提高20%～25%。使用缓冲溶液较单一氢氧化钠溶液对稳定pH值有更好的效果,并且方法简便。另外,硼砂―氢氧化钠缓冲溶液对NaClO滴加速度敏感,控制滴加速度可以有效地提高反应活性。

英文摘要：

TEMPO-mediated oxidation has been reported to effectively convert C6 primary hydroxyl groups to carboxyl groups for better water-solubility.However,the pH decreases continuously during the oxidation process,and it is therefore difficult to maintain the stability of the reaction.The control of pH at a constant level throughout the oxidation process is a complicated task.The applicability of the carbonate buffer system and the borax buffer system with various dropping rate of sodium hypochlorite solution was considered.Both two kinds of buffer solutions provide a stable and mild environment to ensure the quality of products without interfering with the oxidation process.Experimental results showed that the carboxyl content of oxidized cellulose in buffer system increased by 20% to 25% compared with traditional methods.For cellulose,the borax buffer solution can promote mass transfer and accelerate penetration of reaction solution.In order to enhance the performance of buffer solution,sodium hypochlorite solution was added by drops trickling into the reaction system.