Selective and Full Derivatization of Amino Group in Chitosan with Alkyl Chloroformate of Low Stereo-Hindrance
Selective and Full Derivatization of Amino Group in Chitosan with Alkyl Chloroformate of Low Stereo-Hindrance
复制标题
低立体位阻氯甲酸烷基酯选择性完全衍生化壳聚糖中的氨基
DOI：
10.1007/s13233-016-4079-4
复制
发表时间：
2016-07-01
影响因子：
2.4
通讯作者：
Bai, Zheng-Wu
中科院分区：
文献类型：
--
作者：
Feng, Zi-Wei;Huang, Shao-Hua;Bai, Zheng-Wu
甲壳素是产量仅次于纤维素的第二大天然聚合物。1甲壳素脱乙酰化后得到生物相容性和生物可降解性的壳聚糖，2因此被广泛用作各种材料，特别是生物活性材料。例如，由于壳聚糖与蛋白质具有很高的亲和性，因此常被用作药物载体。3通常，壳聚糖衍生物用作吸附剂以从废水中去除过渡金属离子或用作腐蚀抑制剂以保护钢等。3，4通常，具有-NH-CO2-基团的化合物可能具有生物活性，例如，农药通常含有该基团。具有该基团的壳聚糖衍生物可以更优选作为杀虫剂，因为它们在性质上是可生物降解的。这些衍生物对环境无害，有可能成为现有农药的良好替代品。为了制备具有抗菌活性的壳聚糖衍生物，Aiba通过壳聚糖与碳酸二甲酯/碳酸二乙酯反应，合成了壳聚糖甲氧基甲酰胺和壳聚糖乙氧基甲酰胺。5 C？rdenas还用壳聚糖合成了两种类似的产物--氯甲酸甲酯和氯甲酸乙酯。6然而，这些衍生物是由未高度脱乙酰化的壳聚糖制备的。在某些情况下，聚合物的功能与其超结构密切相关。7.高度脱乙酰化的壳聚糖通过完全转化反应衍生化，可能得到规则的高级结构，这类衍生物可能显示出不同的生物活性或其他强大的功能。Okamoto等人从纤维素、直链淀粉、甲壳素和壳聚糖中开发了大量的手性包装材料。8-10结果表明，多糖衍生物的规则的高级结构对手性识别是非常必要的。11，12例如，他们使用完全脱乙酰化的壳聚糖用于手性分离材料的合成，以确保制备的壳聚糖衍生物具有规则的高级结构，这导致对手性化合物的满意的对映体分离。13在他们使用的壳聚糖中没有残留的乙酰基。在我们以前的工作中，我们发现不充分的修饰导致纤维素衍生物的手性分离能力相对较差。14-16相比之下，如果使用高度脱乙酰化的壳聚糖制备手性分离材料，则可以实现强大的对映体分离能力。因此，开发一些能够导致多糖完全衍生化的方法具有重要意义。在本工作中，我们着重于选择性地将壳聚糖的氨基完全转化为-NH-CO2-，而壳聚糖的羟基保持不变。所得产物中仍含有羟基，可作为手性固定相等多种材料的重要中间体，也可作为新型农药。讨论了反应的细节。
Chitin is a natural polymer of the second largest yield, which is only lower than that of cellulose. 1 After deacetylation, chitin affords chitosan that is biocompatible and biodegradable, 2 therefore being widely used as various materials and bioactive materials in particular. For example, because chitosan exhibits high affinity with protein, it is usually applied as drugs carrier. 3 Usually, chitosan derivatives are used as the absorbents to remove transition metal ions from waste water or as corrosion inhibitors to protect steel, etc. 3, 4 Generally, a compound with the group of-NH-CO2-likely is bioactive and for instance, pesticides often contain this group. Chitosan derivatives with this group may be more preferable as pesticides since they are biodegradable in nature. These derivatives are not harmful to environment, thus possibly being good replacements of existing pesticides. In order to prepare chitosan derivatives of antibacterial, Aiba synthesized chitosan methoxyformamide and chitosan ethoxyformamide via the reaction between chitosan and dimethyl/diethyl carbonate. 5 Cάrdenas also synthesized two similar products with chitosan, methyl chloroformate and ethyl chloroformate. 6 However, these derivatives were prepared from the chitosan that had not been highly deacetylated. In some cases, the function of polymers is closely related to their supra-structures. 7 A regular higher order structure of the derivatives is possibly obtainable if highly deacetylated chitosan is derivatized by a reaction with full conversion.This kind of derivatives may show different bioactivity or other powerful function. Okamoto et al. developed a large number of chiral packing materials from cellulose, amylose, chitin and chitosan. 8-10 The results showed that the regular higher order structure of polysaccharides derivatives were very essential for chiral recognition. 11, 12 For example, they employed completely deacetylated chitosan for the synthesis of chiral separation materials to ensure the prepared chitosan derivatives possess regular higher order structure, which caused satisfactory enantioseparation for chiral compounds. 13 There was no residual acetyl group in the chitosan they utilized. In our previous works, we found that insufficient modification caused relatively poor chiral separation capability for cellulose derivatives. 14-16 In contrast, a powerful enantioseparation capability could be achieved if the highly deacetylated chitosan was employed to prepared chiral separation materials. 17 Therefore, developing some methods that can lead to a full derivatization for polysaccharides is of significance. In this work, we focused on selectively derivatizing the amino group of chitosan into-NH-CO2-with a complete conversion, and the hydroxyl group of chitosan remained unchanged. The resulting products still with hydroxyl group can be used as the important intermediates for various materials, such as chiral stationary phases, or they may be served as a new type of pesticides. The details about formylation reaction were discussed.