Study On The Lewis Acidic Ionic Liquids Catalyzed Synthesis Of Bisphenol A Via Condensation Of Phenol With Acetone

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. In search for an environment benign (friendly) chemistry, new, more versatile ionic liquids are widely investigated. The most recent publications in this area focus on the synthesis of new ionic liquids, systematic investigations of their properties and further applications as media and catalysts.Bisphenol A [2, 2-bis(4-hydroxyphenyl)propane; BPA is an important raw material for polycarbonate resins and epoxy resins and also for engineering plastics. Generally, bisphenol A is synthesized by condensation of phenol with acetone in the presence of acid catalysts such as liquid acids (H2SO4 etc.), solid acids (heteropolyacids, heteropoly compounds encapsulated into mesoporous molecular sieves as well as sulfonic acid functionalized mesoporous MCM-41 silica) and cation-exchange resins. Liquid acid catalysts cause equipment corrosion and environmental pollution, and some solid acids are deactivated rapidly due to the build-up of coke. Although cation-exchange resins show a good performance, thermal stability and fouling of the resins are also major problems. The use of room temperature ionic liquids as either solvents or catalysts has gained much attention recently because of the prospects for "green" catalysis. To date the examples of such organic transformations include Diels-Alder, Knoevenagel condensation, Friedel-Crafts, hydrogenation reaction and even enzyme catalyzed reactions.We chose the synthesis of Bisphenol A catalyzed by chloroaluminium ionic liquids with Lewis acidity and compared to traditional heteropolyacids to investigate thecatalytic behavior of ionic liquids. The main results are listed as follow:1. Chloroaluminium ionic liquids and heteropolyacids were synthesized. Chloroaluminium ionic liquids are liquid catalysts at room temperature while heteropolyacids are solid catalysts.2. Synthesis of Bisphenol A catalyzed by chloroaluminium ionic liquids with Lewis acidity has been studied .The results show that this ionic liquid system is of high catalytic activity. While catalyzed by Et3NHCl-AlCl3(XAlCl3=60%), the yield of bisphenol A can reach 85.05% with the selectivity to bisphenol A 94.07% at 60℃ in four hours. At the same time, the catalytic activity of various heteropolyacids are also studied in this paper and among them, SiMogWe shows the highest selectivity and yield of bisphenol A.3. In the synthesis of bisphenol A catalyzed by chloroaluminium ionic liquids, the influence of anions, cations and the constitution of the ionic liquid systems on the selectivity and yield of towards were described in this paper. It indicated that the acidity of these ionic liquid systems can be adjusted. The effects of reaction temperature, reaction time, mole ratio of phenol to acetone and solvent on this catalytic reaction were also investigated. Chloroaluminium ionic liquids are efficient catalysts for the Bisphenol A synthesis. This reaction can be catalyzed by chloroaluminium ionic liquids at milder conditions with higher catalytic activity.4. Heteropolyacids can also be used to catalyze the Bisphenol A synthesis and are easy to separate. But the reaction conditions are not milder with lower selectivity and yield than in the Chloroaluminium ionic liquidsWe conclude that chloroaluminium ionic liquids have good catalytic activity with high yield and good selectivity. Although heteropolyacids are easy to separate from reactant and product, their catalytic activity are lower than chloroaluminium ionic liquids.