Application Of Basic Ionic Liquid [bmim]OH In The Condensation Reactions

Ionic liquids (ILs) have been a bran-new medium and soft functional material by the development of green chemistry these years. Due to their wide liquid range, nonvolatility, adjustability of chemical and physical properties and large windows of electrochemistry, ionic liquids are becoming ever-expanding applications as alternative reaction media and catalysts for organic synthesis, solvents and extractants for separation and electrolytes for electrochemistry. Recently, new ionic liquids are being introduced in which a functional group is incorporated as a part of the cation or anion structure. The most recent publications in this area focus on the applications of acid ionic liquids, but the reports of applications of basic ionic liquids are few. Herein, we investigated the typical basic ionic liquid [bmim]OH in condensation reactions including Knoevenagel condensation, Henry reaction and Perkin reaction.In the preface and review of this paper, we simply introduced the categories and characterities of the functional ionic liquids, and we placed emphasis on the basic ionic liquids. The review focuses on the ionic liquids in condensation reactions including the Knoevenagel condensation, Adol condensation, Witting condensation, Benzoin condensation, Claisen-Schmidt condensation, Mannich reaction, Pechmann condensation, Paal-Knorr condensation.In the part one, we reported the classical Knoevenagel condensation between active methylene compounds containing malononitrile, ethyl cyanoacetate and substituted benzaldehydes. We investigated the mole ration of the basic ionic liquid, the reaction time, the substitute effect of aromatic aldehydes and the recycle times of IL on the reaction. The experimental results showed that basic ionic liquid [bmim]OH played a dual role as solvent and catalyst in the Knoevenagel condensation . The Knoevenagel condensation proceeded efficiently in [bmim]OH at room temperature in 85%-95% yields within 10 to 30 min. The ionic liquid could be reused conveniently.In the part two, we further investigated the basic ionic liquid [bmim]OH in Henry reaction. We also discussed the mole ration of the basic ionic, the reaction time, the substitute effect of aromatic aldehydes and the recycle times of IL on the reaction. The results showed that the basic ionic liquid [bmim]OH is also an efficient reaction medium for Henry reaction. The Henry reaction proceeded efficiently in [bmim]OH at room temperature in moderate yields within 12h. The ionic liquid could be reused conveniently at least 4 times.In the part three, we discussed the basic ionic liquid [bmim]OH in Perkin reaction, we investigated the the reaction time, the scope of temperature, the mole ration of the basic ionic and raw materials and compared with other previously reported procedures. The basic ionic liquid could not be reused for it could be neutralized by formed acetic acid.In summary, the above condensation reactions and the synthetic methods possess such advantages as readily available starting materials, mild reaction conditions, simple operation, high yields, environmentally benign and the potential for recycling of ionic liquids.