Study On Catalytic Synthesis Of Tributyl Citrate From A Series Of Ionic Liquids Containing Imidazolyl Sulfonic Acid

[PS2IMI3PW12O40 and [BS2lM]3PWi2〇4〇,three imidazolyl ptoluenesulfonic acid ionic liquids with different cationic substituents[MIMBS]OTs,[EIMBS]OTs,[PIMBS]OTs,were synthesized to catalyse the synthesis of TBC.The optimum reaction conditions of the five ionic liquids and the reusability of the ionic liquid disulfonic acid in the synthesis of TBC were investigated.The achievements of this paper are as follows:1.Three kinds of imidazolyl p-toluenesulfonic acid ionic liquids[MIMBS]OTs,[EIMBS]OTs and [PIMBSJOTs were synthesized in this work.The ionic liquid synthesized in this paper was characterized by FTIR and ’HNMR.The synthesized p-toluenesulfonic acid ionic liquid was used to catalyze the synthesis of TBC.The effects of the molar ratio of acid to alcohol,the amount of catalyst and the reaction time on the catalytic activity of the three ionic liquid catalysts were investigated.The optimal catalytic reaction conditions were obtained as follows: the molar ratio of CA and n-BuOH was1:5,the reaction time was 3.5 h,The amount of p-toluene sulfonic acid ionic liquid catalyst added was 6.0% n,CA),and the reaction temperature was reflux temperature.Under the optimum reaction conditions,the first conversion of CA is about 98%-99% when the three ionic liquids are used as catalysts.The catalytic activity of ionic liquid [MIMBS]OTs did not significantly decrease after repeated use for 8 times.When the dosage of [MIMBSJOTs was increased to 30% ri(CA)with other conditions unchanged,the catalytic activity of[MIMBSJOTs was not significantly decreased after repeated use for 19 times.2.The heteropolyacid ionic liquids [PS2lM]3PWi2〇4〇 and[BS2lM]3PWi2〇4〇 with disulfonic acid functionalization were synthesized by grafting sulfonic acid groups onto imidazole and reacting with H3PW12O40.It was characterized by FT-IR,’H-NMR and elemental analysis.The phosphotungstate ionic liquid was used to catalyze the synthesis of TBC.By investigating the effects of the molar ratio of CA and n-BuOH,the amount of catalyst added and the reaction time on the catalytic activity of the two heteropoly acid ionic liquid catalysts.The optimal catalytic reaction conditions were as follows: molar ratio of CA and n-BuOH was 1:5,reaction time was 3.5h,The amount of heteropoly acid ionic liquid catalyst added was 0.8 g(2.37% of the total mass of reactants),reaction temperature was reflux temperature.Under these conditions,the first conversion of CA to TBC catalyzed by[PS2IM]3PW,2〇4〇 and [BS2IM]3PWi2〇4〇 can reach 98.81% and 96.13%,respectively.