Synthesis of citric acid ester catalysed by trifluoromethanesulfonic acid

In the investigation, an efficient green catalyst trifluoromethanesulfonic acid (CF ₃SO ₃H) is employed in the synthesis of green plasticizer tributyl citrate, which needs shorter reaction time (5 hours) and smaller amount of catalyst (0.1% of CF ₃SO ₃H). Moreover, CF ₃SO ₃H is applied as catalyst in the synthesis of acetyl tributyl citrate from citric acid via an integration process. The final yield (for two steps) and the purity are 87.1% and 99.1%, respectively. It indicates that he integration process not only greatly simplifies the process and reduces the production cost, but also is environment-friendly, which is very promising for the potential industrial application. Besides that, various alcohols and acid anhydrides are employed to prepare a series of potential green plasticizers via the optimal reaction conditions obtained above.