Sirviö Juho Antti, Heiskanen Juha P
Fibre and Particle Engineering Research Unit and Research Unit of Sustainable Chemistry, University of Oulu, P.O. Box 4300, FI-90014 Oulu, Finland.
ACS Omega. 2019 Sep 12;4(13):15702-15710. doi: 10.1021/acsomega.9b02350. eCollection 2019 Sep 24.
A one-pot coupling of starch with alkyl amine was studied using dimethyl carbonate (DMC) as the coupling agent. Although reaction occurred without a catalyst (24 h, 70 °C), different catalysts, namely, imidazole, tetramethylguanidine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and combinations thereof were investigated to improve the reaction efficiency. When 20 mol % DBU was used as a catalyst, the degree of substitution (DS) could be improved from 0.05 to 0.15 compared to the noncatalyzed reaction. When the amount of DBU was decreased to 5 mol %, catalytical activity remained, albeit with a slightly lower DS (0.09). Temperature did not have a significant effect on the DS but it could be used to alter the solubility of the product. Based on chemical analysis, the alkyl group was attached to starch by the formation of a carbamate group. As the carbonyl carbon in the carbamate originated from DMC, which, in turn, can be produced from carbon dioxide on an industrial scale, the current study provides a conventional way to utilize carbon dioxide-based chemicals in the functionalization of a natural polymer. DMC is also biodegradable and classified as a nonvolatile organic component, making it an environmentally desirable coupling agent.
以碳酸二甲酯（DMC）作为偶联剂，研究了淀粉与烷基胺的一锅法偶联反应。尽管在无催化剂的情况下反应也能发生（24小时，70℃），但为了提高反应效率，研究了不同的催化剂，即咪唑、四甲基胍、1,8 - 二氮杂双环[5.4.0]十一碳 - 7 - 烯（DBU）及其组合。当使用20摩尔%的DBU作为催化剂时，与无催化反应相比，取代度（DS）可从0.05提高到0.15。当DBU的用量降至5摩尔%时，催化活性仍然存在，尽管取代度略低（0.09）。温度对取代度没有显著影响，但可用于改变产物的溶解度。基于化学分析，烷基通过形成氨基甲酸酯基团连接到淀粉上。由于氨基甲酸酯中的羰基碳源自DMC，而DMC又可在工业规模上由二氧化碳生产，因此本研究提供了一种在天然聚合物功能化中利用二氧化碳基化学品的常规方法。DMC也是可生物降解的，并且被归类为非挥发性有机成分，使其成为一种环境友好的偶联剂。
