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

Abstract

AbstractIn 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 1H NMR, 13C NMR, 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 1st run.