Mechanistic Investigation of DBU-Based Ionic Liquids for Aza-Michael Reaction: Mass Spectrometry and DFT Studies of Catalyst Role
摘要:
1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU)-based ionic liquids (ILs) has exhibited a high catalytic activity in the aza-Michael reactions compared to conventional catalysts and with imidazole-based ILs. In the present work DBU-based ILs showed high catalytic potential for aza-Michael addition of aromatic amines to 2-cyclohexen-1-one under solvent-free condition. Electrospray ionization-mass spectrometry (ESI-MS) and density functional theory studies have been carried out to provide an effective activation mode of DBU-based ILs in aza-Michael addition. Our results show that both the presence of the acid hydrogen in the IL and the ability of the anion to carry out a hydrogen bond with the -NH2 group of the arylamine are fundamental for the reaction catalysis. The catalytic model proposed can be used for the rational development of new ILs with excellent catalytic properties.
Cyclic amidine hydroiodide for the synthesis of cyclic carbonates and cyclic dithiocarbonates from carbon dioxide or carbon disulfide under mild conditions
作者:Naoto Aoyagi、Yoshio Furusho、Takeshi Endo
DOI:10.1016/j.tet.2019.130781
日期:2019.12
Hydroiodides of amidines can catalyze the reaction of carbon dioxide and epoxides under mild conditions such as ordinary pressure and ambient temperature, and the corresponding five-membered cyclic carbonates were obtained in high yields. The reaction of epoxide with carbon disulfide was also examined under the same conditions. Detailed investigation showed that the catalytic activity was highly affected
Tungstate ionic liquids as catalysts for CO2 fixation into epoxides
作者:Roberto Calmanti、Maurizio Selva、Alvise Perosa
DOI:10.1016/j.mcat.2020.110854
日期:2020.5
spectroscopic characterisation (FT-IR, 1H-, 13C-and 183W-NMR) and a comparison of their properties and possible applications in catalysis. The synthetic procedures to obtain the ionic liquids rely on anion exchange and acid-base reactions – including an innovative route for the synthesis of tungstate and peroxotungstate ionic liquids using, for the first time, a halide-free organic ionic liquid as
摘要 本文描述了一系列钨酸铵、鏻、咪唑鎓和二氮杂环癸烯钨酸盐和过氧钨酸盐离子液体的合成、它们的全光谱表征(FT-IR、1H-、13C-和 183W-NMR)以及它们的性质和可能的比较催化中的应用。获得离子液体的合成过程依赖于阴离子交换和酸碱反应——包括首次使用无卤有机离子液体作为前体来合成钨酸盐和过钨酸盐离子液体的创新路线。钨酸盐离子液体被用作在氧化苯乙烯以及一系列其他环氧化物中固定 CO2 的催化剂,以产生相应的碳酸盐。在优化条件下,仅使用钨酸丁基甲基咪唑鎓,在 90 °C 下以高达 67% 的收率获得碳酸苯乙烯,通过将钨酸四丁铵与溴化物偶联,以 91% 的收率获得。初步测试表明,相同的催化剂也可以促进环氧化反应,为它们在烯烃的直接氧化羧化中的应用铺平了道路。
Protic ionic liquids tailored by different cationic structures for efficient chemical fixation of diluted and waste CO<sub>2</sub> into cyclic carbonates
Two series of super-base-derived hypergolic ionic liquids were synthesized, which all exhibit good hydrolytic stability to heat and expected hypergolic properties upon contact with WFNA.
A vulcanizable fluoroelastomer composition comprising (a) a vulcanizable fluoroelastomer, (b) a vulcanizing agent containing a polyol compound as a cross-linker, and (c) an aliphatic amine compound represented by the general formula RαNHβ, wherein R represents alkyl, α represents an integer of 1 to 30, and β is equal to 3 minus α. The composition can not only provide a vulcanized article having excellent tensile characteristics, heat resistance, oil resistance and high-temperature sealability comparable to those of known conventional fluoroelastomer vulcanizates, but also achieve remarkable improvements in the mold release performance of a vulcanizing/molding product thereof, the flowability and rollability in the vulcanizing/molding work thereof, and the operability particularly in the injection molding thereof.