Design and Synthesis of New Sulfonic Acid Functionalized Ionic Liquids as Catalysts for Esterification of Fatty Acids with Bioethanol

In this study, three types of sulfonic acid group functionalized ionic liquids (SAILs) with a different number of catalytic groups and lipophilicity were synthesized and characterized by FT-IR, NMR, and MS analyses. Their catalytic activities were studied in a model esterification of oleic acid with ethanol; heating in a microwave reactor was also used. The experimental results indicated that SAIL, with the lipophilic alkyl chain, performed the best due to its increased solubility in the reaction mixture. Microwave heating was found to be more effective than conventional heating. Recycling experiments show that these novel SAILs can be reused without significant loss of the catalytic activity.

Automated summary

Three types of sulfonic acid group functionalized ionic liquids (SAILs) with different catalytic groups and lipophilicity were synthesized and characterized. The catalytic activities of these SAILs were studied in an esterification reaction, and microwave heating was used. The results showed that the SAIL with a lipophilic alkyl chain had the best performance due to its increased solubility in the reaction mixture. Microwave heating was more effective than conventional heating. Recycling experiments demonstrated that these novel SAILs could be reused without significant loss of catalytic activity.