Synthesis And Processing Research Of Esterification By Functionalized Acid Ionic Liquids

Ionic Liquids are salts with room temperature, which exert efficient catalytic activityin esterification. Ionic liquids have received considerable attentions of scientists becauseof their environmentally friendly and wide applications. However, the traditional ionicliquids have many shortcomings, such as the high usage and price, the hardness of recycle.Developing new types of functionalised acidic ionic liquids deserves our attention.To economize the cost of catalysts, extend their range of application in esterification,14kinds of Br nsted acidic ionic liquids had been synthesized though two-step by usingN-methylimidazole, pyridine,1,3-propane sultone,1,4-butane sultone and bromoalkanesas source in this paper. Their structures, thermal stabilities were characterized andevaluated using NMR, FT-IR and1HNMR. The results exhibited that the decompositiontemperature of ionic liquids were higher than300℃, environmental pollution were lesscompared with traditional organic solvent, which demonstrated their wide industrialapplication prospect.The catalytic performances of14kinds of acidic ionic liquids in the reaction systemof ethyl acetate were investigated, the results obtained was that [HSO3-pmim]HSO4showed highest catalytic activity. Moreover, continuous catalytic distillation experimentsof producing ethyl acetate were conducted, and the effect of reaction temperature、feedratio、reflux ratio on the reaction were inspected respectively to determine the optimaltechnological conditions. Under the optimal reaction conditions, continuous catalyticesterification were conducted, the results of which showed that the esterification of ethylacetate could last15days or so.The catalytic performances of14kinds of acidic ionic liquids in the reaction systemof diisopropyl succinate were explored, the relationship between the structure andcatalytic properties of ionic liquids was obtained.[HSO3-pmim]HSO4showed highestcatalytic activity, then the catalytic performance of [HSO3-pmim]HSO4in the maleate andsuccinate were probed. The optimal conditions for the synthesis of succinate ester wereobtained. Moreover, the catalyst was recycled for more over6times without substantialdiminution in activity.Sulfonic acid-functionalised ionic liquids [HSO3-pmim]HSO4had good activities tothe above target reactions, and they have more advantages than traditional catalysts. The ionic liquids could be easily separated from products due to their immiscibility withproducts which were readily post-treated, the catalyst could be reused with low pollutionto environment. Thus, reported dication ionic liquid was a promising catalyst foresterification reaction.