Eco-friendly acetylcholine-carboxylate bio-ionic liquids for controllable N-methylation and N-formylation using ambient CO2 at low temperatures. Issue 3 (10th January 2019)

• Record Type: Journal Article
• Authors: Zhao, Wenfeng; Chi, Xiaoping; Li, Hu; He, Jian; Long, Jingxuan; Xu, Yufei; Yang, Song
• Is Part Of: Green chemistry. Volume 21:Issue 3(2019)
• Page Start: 567
• Page End: 577
• Publication Date: 2019-01-10
• Subjects: Environmental chemistry -- Industrial applications -- Periodicals; Environmental management -- Periodicals; 660
• DOI: 10.1039/c8gc03549k
• Languages: English
• ISSNs: 1463-9262

Abstract

Abstract : A sustainable and recyclable ionic liquid catalytic system is developed to be efficient in N -methylation or N -formylation of amines with CO2 under mild conditions. Abstract : Catalytic fixation of CO2 to produce valuable fine chemicals is of great significance to develop a green and sustainable circulation of excessive carbon in the environment. Herein, a series of non-toxic, biodegradable and recyclable acetylcholine-carboxylate bio-ionic liquids with different cations and anions were simply synthesized for producing formamides and methylamines using atmospheric CO2 as a carbon source, and phenylsilane as a hydrogen donor. The selectivity toward products was tuned by altering the reaction temperature under solvent or solvent-free conditions. N -Methylamines ( ca. 96% yield) were obtained in acetonitrile at 50 °C, while N -formamides ( ca. 99% yield) were attained without a solvent at 30 °C. The established bio-ionic liquid catalytic system found a wide range of applicability in substrates and possessed a high potentiality in scale-up to gram-grade production. The developed catalytic system was fairly stable, which could be easily reused without an apparent loss of reactivity, possibly due to the strong electrostatic interactions between the cation and anion. The combination of experimental and computational results explicitly elucidated the reaction mechanism: PhSiH3 activated by a bio-IL was favorable for the formation of silyl formate from hydrosilylation of CO2, followed by a reaction with an amine to give an N -formamide, while an N -methylamine was formed by further hydrosilylation of the N -formamide.