High-efficient esterification of rosin and glycerol catalyzed by novel rare earth Lewis acidic ionic liquid: Reaction development and mechanistic study

• Synergistic complexation of IL obviously decreased orbital level energies and energy barriers. • IL had excellent catalyst performance, reusability and general applicability. • Acid value of the product reached 8.2 mg KOH g –1 at 220 °C for 8 h. As one of the most important modified products of rosin, rosin glyceride was widely used in many aspects. However, the preparation of rosin glyceride is always unfriendly due to the use of liquid catalyst, such as H 2 SO 4 and H 3 PO 4 . The rosin glyceride with low acid value was synthesized in vacuum conditions using a novel Lewis acidic ionic liquid 1–butyl–3–methylimidazolium chloroscandinate[BuMeim][Sc 2 Cl 7 ] as catalyst. The [BuMeim][Sc 2 Cl 7 ] is of excellent catalytic activity and stability. The efficient catalytic activity was studied via the combined Density Functional Theory (DFT) and experimental conditions. The DFT proved the free energy of the esterification could reach to 31.6 Kcal/mol, which illuminates that the excellent coordination of the anions and cations in the [BuMeim][Sc 2 Cl 7 ] greatly reduces the reaction energy barrier and promotes the efficient progress of the reaction. As a result, [BuMeim][Sc 2 Cl 7 ] is a good catalyst for the esterification of rosin and glycerol to prepare rosin glyceride. Furthermore, [BuMeim][Sc 2 Cl 7 ] could be a potential catalysts for the other esterification.