The Synthesis Of Basic Ionic Liquid And Its Application In Organic Reactions

Ionic liquids as a new type of green solvents, These salts have non-volatility, nonflamblity, high thermal stability, wide liquid range, good electrolytic properties with large electrochemical potential window. Due to their excellent properties, which have been successfully applied to organic synthesis, catalytic chemistry, electrochemistry, and materials science and other fields. For a specific ionic liquid, not all of the reactions can be catalyzed, to a certain extent, hinder their application. Therefore, to explore simple and efficient novel ionic liquid, and open up new areas of application become an important component for the study of ionic liquids. In this work, some novel imidazolium ionic liquids have been prepared successfully and the new applications of them in basic catalysis have been found as follows.Basic ionic liquid 1-ethyl-3-methylimidazolium diethylphosphate ([Emim]+[(EtO)2(PO)O]–)was introduced as the catalyst for the Knoevenagel reaction of aldehydes with active methylene compounds. The catalytic activity of the ionic liquid was investigated with ethanol as the solvent and in the case without the presence of the solvent. The results show that the condensations of aromatic aldehydes proceed efficiently at room temperature with ethanol as the solvent to obtain the E-isomers in high yield (73.2%～97%) in the presence of 20% ionic liquid. At the solvent-free condition, the Knoevenagel reactions of aromatic aldehydes proceed smoothly (1-10 min) in the presence of 10% ionic liquid by mechanochemical grind. Comparing to the reationswith ethanol as the solvent, these reactions can be carried out faster. Another feature of the methodology at the solvent-free condition is the condensation of aliphatic aldehydes with active methylene compounds, which is not easy to achieve by conventional reagents. The ionic liquid could be recycled five times and a yield of 85.9% of the last run was obtained.A novel basic ionic liquid paired by 1-(2-aminoethyl)-3-methylimidazolium cation and imidazolide anion ([NH2Emim]IM) was synthesized. The ionic liquid was characterized by 1H NMR and ESIMS and its physical properties was investigated. Isoxazols were synthesized by the three component condensation reactions of ethyl acetoacetate(Ethyl benzoylacetate), aromatic aldehydes and Hydroxylamine hydrochloride in the presence of ionic liquid [NH2Emim]IM. The effects of ionic liquid as catalyst in Knoevenagel reaction were also investigated. Many factors were discussed, such as the reaction time, the dosage of catalyst, reaction substrate, Reusability of ionic liquid, as well as comparison with other catalyst. And we come to conclusion that the resulting ionic liquid has many advantages compare with conventional catalysts. Such as high yields, enhanced rate, pollution-free and recycling. A convenient and efficient method for synthesis of substituted 2-amino-2-chromenes by the reaction of arylidenemalononitriles and 1-naphthol(2-naphthol, resorcinol, Dimedone) or via one-pot three-component condensation of aromatic aldehydes with malononitrile and 1-naphthol(2-naphthol, resorcinol, Dimedone) has been developed by using the inexpensive and environmentally friendly reagent [NH2Emim]IM in aqueous medium. We found that the ionic liquid has good catalytic properties in the synthesis of 2-amino-2-chromenes, and short time was used and had a high yield(80%-94%). In this catalyst system, the reaction of a series of aromatic aldehydes, phenol (resorcinol, Dimedone) were programmed and a mechanism was postulated as well. the effects of different kinds of catalysts and reactants to the reaction were also studied. The ionic liquid could be recycled and reused for five times without noticeably decreasing the catalytic activity.