Synthesis of the carboxyl and pyridine functional ionic liquids

The effects of different solvents on synthesis of base functional ionic liquid, butyl pyridinium hydroxide ([bPy]OH), from butyl pyridinium bromine ([bPy]Br) were investigated systematically using KOH/NaOH as the base agent and strong base anion exchange resin. The results showed that the yield of [bPy] OH achieved 35% with the molar ratio of 1:1.1 ([bPy] Br to NaOH) using dichloromethane under room temperature. With isopropanol and 8 h of the reaction time, the yield could reach 88% with byproducts. The yield of 97% without byproduct was achieved by using strong base anion exchange resin in column chromatography static reaction for 0.25 h. The yield of carboxyl and pyridine functional ionic liquids based on neutralization method, exchange method and one-step method were compared and the results showed that the one-step method possessed the maximum yield of 88% with 3 h of the reaction time at room temperature.