Design of Water Stable 1,3-Dialkyl-2-Methyl Imidazolium Basic Ionic Liquids as Reusable Homogeneous Catalysts for Aza-Michael Reaction in Neat Condition

摘要

In this study,new members of mono cationic basic ionic liquids were synthesized as water stable viscous liquid consisting of 1,3-dialkyl-2-methyl imidazolium cation and acetate(or hydroxide)anion.Their structures were determined using 1HNMR,~(13)CNMR,FT-IR and elemental analysis.Thermogravimetric analysis displayed maximum stabilities of six ionic liquids up to 260 °C.The UV-Vis technique was employed to determine their comparable Hammett basicity order.Thermally stable five ionic liquids with less moisture content showed their catalytic activities by formation of 85–97% yields of β-amino carbonyl compound for the model Aza-Michael reaction of piperidine and acrylonitrile in neat condition with 2 and 5 mol% of catalysts for 5–15 min at room temperature.The optimized two catalysts [dbIm]OH and [daIm]OAc were reused efficiently with slight loss of activity for four cycles after the 1~(st)run.