Synthesis And Esterification Properties Of Acid Ionic Liquids

Esters are fine chemical products with wide applications.At present,sulphuric acid is mostly used as catalyst in the esterification process of acid and alcohol in industry.This process has high yield and mature process conditions.However,serious corrosion to the equipment and a large amount of waste water are inevitable.The acidic ionic liquids can be adjusted by the design of anions and cations and they are suitable for catalytic esterification.The ionic liquids have low corrosivity to the equipment and can be reused after the reaction.In this paper,two kinds of short chain carboxylic acid esters and two kinds of long chain carboxylic acid esters were selected and we tested the catalytic performance of the ionic liquids.Firstly,Lewis acidic ionic liquids were synthesized.The ionic liquids were characterized by FT-IR and the performance of synthesis of ethyl acetate was investigated.The optimum catalyst was selected and the optimum process conditions were determined.The yield of ethyl acetate could reach 96.58%.The ionic liquid was reused for 6 times and it still kept a high activity.Secondly,four Br（?）nsted acid ionic liquids with the same cation and different anions were synthesized,the ionic liquids were characterized by FT-IR and the solubility,acidity and corrosivity were also measured.Using the ionic liquids as the catalyst,the ethyl laurate was synthesized and different ionic liquids had different performances.The results showed that the ionic liquid which had HSO₄^-had a better performance.[DABCO-PS][HSO₄]was chosen as the catalyst and the synthesis process was optimized by response surface methodology.Under the optimum conditions,the conversion of lauric acid was 97.10%,and the ionic liquid was reused for 6 times and it still kept a high activity.Then,four Br（?）nsted acid ionic liquids with the same anion and different cations were synthesized.The ionic liquids were characterized by ¹HNMR,FT-IR,elemental analysis and TG-DSC.The corrosivity and acidity of the ionic liquids were determined and the catalytic performance of ionic liquids was investigated by synthesis of isopropyl myristate.The synthesis process was optimized by response surface methodology.Under the optimum conditions,the conversion of myristic acid was 95.73%,and the ionic liquid was reused for 6 times and it still kept a high activity.Finally,Br（?）nsted-Lewis acidic ionic liquids were synthesized and the ionic liquids were characterized by ¹HNMR,FT-IR.The acidity and corrosivity of ionic liquids were investigated and the catalytic performance of ionic liquids was investigated by synthesizing n-butyl acetate.The optimization of the esterification process was investigated by the response surface methodology.Under the best conditions,the yield of n-butyl acetate was 97.28%.The ionic liquid was reused for 6 times and it still kept a high activity.