Synthesis of tributyl citrate catalyzed by SO_3H functionalized ionic liquid

The esterification of citric acid and n-butanol was carried out using SO3H functionalized ionic liquid as the catalysts.The effects of reaction time,mole ratio of reactants,amount of catalysts and different anions and cations on the yield of tributyl citrate(TBC) were investigated.Results show that the ionic liquid were very efficient for the reaction with the yield of 99% in mild conditions.The optimum reaction condition:mole ratio of citrate acid to butanol was 1 ∶4.5,catalyst amount was 1% of reactants and reaction time was 4 h.