Role of Anion and Cation in the 1-Methyl-3-butyl Imidazolium Ionic Liquids BMImX: The Knoevenagel Condensation
1-Methyl-3-butylimidazolium ionic liquids BMImX (X anions: Ac−, HCO3−, Cl−, BF4−, PF6−, I−, CF3CO2−, (CF3SO2)2N−, CF3SO3−) were used as catalysts in the Knoevenagel condensation reaction. The catalytic activity was compared with that of the inorganic salts NaAc, NaHCO3, NaCl. Whereas it is quite important to select suitable cation and anion depending on the purpose, the basicity of the anion X−and the ability of the counter-ion BMIm+to avoid the ion pairing with anion X−was investigated.