当前位置: X-MOL 学术Carbohydr. Polym. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
‘Chitosan in water’ as an eco-friendly and efficient catalytic system for Knoevenagel condensation reaction
Carbohydrate Polymers ( IF 10.7 ) Pub Date : 2018-09-06 , DOI: 10.1016/j.carbpol.2018.09.008
Dhiraj Rani , Priyanka Singla , Jyoti Agarwal

The catalytic activity of commercially available chitosan has been investigated for the Knoevenagel reaction of ethylacetoacetate (EAA)/dimethylmalonate (DMM) with arylaldehydes. Among all the screened solvents, Chitosan performed the best in water as reaction medium. Substrate scope was evaluated by using various arylaldehydes and it was observed that presence of electron donating groups on aldehydes reduce the yields, while electron-withdrawing groups increase the yields. In case of the reaction of 4-bromobenzaldeyde with EAA, the lower yield of the corresponding product 14 was obtained due to the high stability of imine intermediate formed and this postulate was proved by experiments as well as theoretical calculations. In case of EAA, the E/Z stereochemistry of the corresponding products was assigned based on NOESY experiment.



中文翻译:

“水中的壳聚糖”作为Knoevenagel缩合反应的生态友好型高效催化体系

对于乙酰乙酸乙酯(EAA)/丙二酸二甲酯(DMM)与芳醛的Knoevenagel反应,已经研究了市售壳聚糖的催化活性。在所有筛选出的溶剂中,壳聚糖在水中作为反应介质表现最佳。通过使用各种芳基醛来评估底物范围,并且观察到醛上存在给电子基团会降低产率,而吸电子基团会提高产率。如果4-溴苯甲醛与EAA反应,则相应产物14的收率较低由于形成的亚胺中间体具有很高的稳定性,因此获得了该化合物,并通过实验和理论计算证明了这一假设。如果是EAA,则根据NOESY实验指定相应产品的E / Z立体化学。

更新日期:2018-09-07
down
wechat
bug