Abstract

1,8-Diazabicyclo [5.4.0] undec-7-ene functionalized cellulose nanofibers (CNF@DBU[Cl]) were simply prepared and characterized by analytical techniques. Scanning electron microscope confirmed that CNF@DBU[Cl] was formed with average size of 30–60 nm. X-ray diffraction of CNF@DBU[Cl] showed that the crystalline structure of the cellulose nanofibers was remained unchanged after functionalization. According to elemental analyses and thermal gravimetric analysis, the loading amount of organic group on cellulose nanofibers was found to be 1.46 mmol/g. The catalytic activity of DBU functionalized cellulose nanofibers was studied for the synthesis of biologically important tetraketone derivatives in the reaction of aldehydes with 1,3-dicarbonyl compounds. In the presence of CNF@DBU[Cl], the corresponding tetraketones were obtained in 80–96% yields under very mild reaction conditions. The catalyst was recovered and reused four successive runs without significant loss of catalytic activity. This method showed several significant advantages including short reaction times, high yields of products, use of various substrates, convenient work-up, no necessity of extraction or chromatographic purification steps, environmentally friendly conditions and lack of use of any harmful solvent.

Graphic abstract

中文翻译：

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1,8-二氮杂双环[5.4.0]十一碳烯-十一烯官能化纤维素纳米纤维，是在水性介质中合成四酮的有效且可重复使用的纳米催化剂

摘要

简单地制备1,8-二氮杂双环[5.4.0]十一碳烯-烯官能化纤维素纳米纤维（CNF @ DBU [Cl]）并通过分析技术进行表征。扫描电子显微镜证实形成了CNF @ DBU [Cl]，平均尺寸为30-60 nm。CNF @ DBU [Cl]的X射线衍射表明，功能化后，纤维素纳米纤维的晶体结构保持不变。通过元素分析和热重分析，发现纤维素纳米纤维上有机基团的负载量为1.46mmol / g。研究了DBU官能化纤维素纳米纤维在醛与1,3-二羰基化合物反应中的合成对生物重要的四酮衍生物的催化活性。在CNF @ DBU [Cl]存在的情况下，在非常温和的反应条件下，以80-96％的产率获得了相应的四酮。回收催化剂并将其连续四个循环重复使用，而催化活性没有明显损失。该方法显示出几个显着的优点，包括反应时间短，产物的收率高，使用各种底物，后处理方便，无需萃取或色谱纯化步骤，环境友好的条件以及无需使用任何有害溶剂。

图形摘要