Catalytic Synthesis Of Tri-n-butyl Citrate And Acetyl Tri-n-butyl Citrate

Tributyl citrate(TBC) was catalytically synthesized using citric acid and n-butanol as reactants. Acetyl tributyl citrate(ATBC) was catalytically synthesized using TBC and acetic anhydride as reactants.Sodium bisulfate was used as catalyst firstly to synthesize TBC. The effect of molar ratio of reactants, reaction time, dosage of catalyst on the yield of TBC were investigated. The optimized conditions were as follows: molar ratio of n-butanol to citric acid was 4.6, reaction time was 140 minutes, dosage of catalyst was 4% of citric acid weight. Under the above conditions, the yield of TBC reached 97.5%. Meanwhile, a macroporous strongly acidic cation exchange resin and 4A zeolate were also used as catalysts, the results showed that the yields of TBC were 83.0% and 76.5% respectively under the optimized conditions.Using TBC and acetic anhydride as reactants, sodium bisulfate and a macroporous strongly acidic cation exchange resin as catalysts, synthesis of ATBC was studied. The effect of molar ratio of reactants, reaction time and temperature, dosage of catalyst on the yield of TBC were investigated. Under the optimized conditions, the yields of ATBC catalyzed by such two catalysts were 99.5% and 99.8% respectively with the conversion of TBC almost 100%. 4A and HZSM-5 zeolates were tried as catalysts, but the results were poor.ATBC was also synthesized in a tubular fixed-bed reactor. A macroporous strongly acidic cation exchange resin was used as catalyst as well as the packing material. The activity of catalyst became better after being wetted by the reactants and the yield of ATBC was high even under low temperture. The effect of molar ratio of reactants, temperature of circulated water, flow rate and the height of catalyst loaded on the yield of TBC were investigated. Under appropriate conditions, the conversion of TBC was about 100%.The purity of TBC and ATBC after purification were all higher than 99%analyzed by GC.