Synthesis And Application Of Novel Quaternary Ammonium Ionic Liquids

Ionic liquids (ILs) or molten salts are in general defined as liquid electrolytes composed entirely of ions. They also are called as room-temperature molten salts because their compositions are similar to common salts but their melting points are lower. They are getting more and more attentions from academia and industry dew to their special charaters, such as a relatively wide electrochemically stable window, good electrical conductivity, high ionic mobility, a broad range of room-temperature liquid compositions, negligible vapor pressure, and excellent chemical and thermal stabilities. They have been widely used as a kind of new environment friendly materials.Firstly the research background of ionic liquids has been introduced in this paper. Then the methods of synthesis, the properties and their applications in the analytical chemistry, organic chemistry, polymers and other reactions have been reviewed. Notwithstanding the unique advantages of ionic liquids as reaction media and catalysts, currently they have not been widely applied in industry. The reason is probably related to the high cost of ionic liquids, the difficulty in separation or recycling, the paucity of data regard to their toxicity and biodegradability, and so on. In order to solve these problems and to apply ILs in industry, the novel quarterary ammonium acidic ionic liquids, from cheap raw materials, without solvent, were synthesized in one step. They are water insensitive, relatively cheap, Bro|¨nsted acidic and easy to prepare.Secondly the application of novel quarterary ammonium acid ionic liquids in the synthesis of cinnamic acid has been studied in the fourth part. They have been used both as a catalyst and environmentally benign solvent for the synthesis of cinnamic acid, eliminating the need for a volatile organic solvent and additional catalyst. The results clearly demonstrate that these ILs can be easily separated and reused without losing their activity and quality. And the yields obtained with this methodology are significantly increased in comparison with those reported in organic solvents to date,having the industrial application value. The mechanism of the hydrolyzation in acid ionic liquids has been discussed. The good conversion and high yield of cinnamic acid could be obtained with 1:1 mole ratio under 120°C for 8h in the [Et3NH][HSO4]. Quarterary ammonium acid ionic liquids are found to work well as acid catalysts in the synthesis of bisphenol A by condensation of phenol with acetone in the fifth part. Not only this method provides a stable catalysis, but also it succeeds in recycling the catalysis. Filtration is sufficient to remove products from the solution, and the yield can be obtained by 83.5% under the optimized condition. The mechanism of synthesis in quarterary ammonium acid ionic liquids has been investigated, too.Finally, we could conclude that the quaternary ammonium ionic liquids were very attractive ionic liquids in industry. They could be applied in the the synthesis of cinnamic acid and bisphenol. The key problems and the trend of development of ionic liquids have been summarized. For the industry application, ionic liquids are usually expensive compared to the traditional organic solvents now. However, they will provide a good alternative way for the industry to improve the environment and bring benefit to the whole world in the future.