Condensation of Furfural to Furoin Catalyzed by Highly Unsaturated Ionic Liquid and Validation with Machine Learning

Six highly unsaturated diimidazole ionic liquids (ILs) were synthesized and applied to catalyze the condensation of furfural into furoin. The effects of solvents and reaction conditions on the reaction were also investigated. Results showed that the δH(C-2) chemical shift of the imidazolium ring could reflect the catalyst’s catalytic performance. CH2Cl2 facilitated the deprotonation of the ILs and product separation, leading to the highest furoin yield. While the presence of 10% acetone could enhance contact between the catalyst and furfural, thereby increasing the yield. RSM, ANN, and SVR demonstrated the reliability and accuracy of the experimental results. The kinetic calculation was consistent with the observed rapid completion of the reaction under mild conditions. What’s more, energy-level calculations revealed that the nucleophilic reaction with the second furfural molecule to form furoin constitutes the rate-determining step. This work is expected to provide valuable guidance for catalyst design and process optimization.