Abstract: Novel PEG ionic liquids(IL200, IL400, IL1000) were prepared and used as the solvent for the acetalization of aromaldehyde and ethylene glycol catalyzed by p-toluenesulfonic acid. The ionic liquids and toluene have the advantages of both homogeneous and heterogeneous phases at different temperatures with the ease of product as well as catalyst separation. The catalyst(p-toluenesulfonic acid) was soluble in ionic liquids and insoluble in toluene. The optimum conditions: ILs 3 mL, toluene 5 mL, p-toluenesulfonic acid 6 mmol, benzaldehyde 5 mmol, ethylene glycol 15 mmol, the yield was 92% in 4 h at 80 ℃. The yields of the acatalization of aromaldehyde and ethylene glycol catalyzed by the system was 54.6%—97.8%. The ionic liquids played the role of solvent and the catalyst system were recycled up to 5 times without any significant loss of activity.

Key words: PEG, Thermoregulated ionic liquids, Aromaldehyde, Acetalization, Biphase system